Axon Quotes

There's magic in recognizing a kindred spirit, and an even greater power in letting yourself love them. When it scares you, let it - that's your ego letting go.

When rationality begins to break down, the circuits of the human brain can overload. Axons grow bright and feverish. Hallucinations turn real: the quicksilver puddle at the point where perspective makes parallel lines seem to intersect is really there; the dead walk and talk; a rose begins to sing.

He was my teacher, and he had wrapped himself, his elaborate historical self, into this package, and stood in front of the high windows, to teach me my little lesson, which turned out to be not about Poland or fascism or war, borderlines or passion or loyalty, but just about the sentence: the importance of, the sweetness of. And I did long for it, to say one true sentence of my own, to leap into the subject, that sturdy vessel traveling upstream through the axonal predicate possibility; into what little we know of the future, of eternity.

Love is like sunlight,” she said when I didn't respond. “You can give all of yourself to someone and still have all of yourself left to give to others, and to yourself. To your work. To anything or anyone you choose. Love isn't like food; you won't starve anyone by giving It freely. It's not a finite resource.

it occurred to him that kids were better at almost dying, and they were also better at incorporating the inexplicable into their lives. They believed implicitly in the invisible world. Miracles both bright and dark were to be taken into consideration, oh yes, most certainly, but they by no means stopped the world. A sudden upheaval of beauty or terror at ten did not preclude an extra cheesedog or two for lunch at noon. “But when you grew up, all that changed. You no longer lay awake in your bed, sure something was crouching in the closet or scratching at the window ... but when something did happen, something beyond rational explanation, the circuits overloaded. The axons and dendrites got hot. You started to jitter and jive, you started to shake rattle and roll, your imagination started to hop and bop and do the funky chicken all over your nerves. You couldn’t just incorporate what had happened into your life experience. It didn’t digest. Your mind kept coming back to it, pawing it lightly like a kitten with a ball of string ... until eventually, of course, you either went crazy or got to a place where it was impossible for you to function.

I dismiss the pachyderms and the asses in favor of my axons and dendrites.

As it turns out, the higher your aerobic fitness, the healthier your hippocampus. Not to mention the overall connectivity of your Default Mode Network and multiple axon bundles, so . . .” I shrug. “I find myself resentfully acknowledging that according to science, exercise is a good thing.

Knowledge emerged about synapses, neurotransmitter-ology was born, and this idea was modified—a new memory requires the formation of a new synapse, a new connection between an axon terminal and a dendritic spine.

Treatments worked well enough for us to get by. Most people lived into old age, but the medication, like everything else, has never been free. Life was a privilege, not a right, apparently. Something you had to struggle for when you were unlucky enough to be born at the intersection of poverty and bad genes.

And there I was, a woman who yearned so hard for the sky there had to be stars in my blood, yet I was stuck in Heliodor City, missing it all.

So neurons talk to each other by squirting electrically charged molecules from the axon of one to a dendrite on another.

The incoming fibers that carry messages from other cells are called dendrites. The outgoing fibers that send messages to other cells are called axons.

if one neuron wants to talk with another neuron, it sends an electrical signal down its axon to meet one of the other neuron’s dendrites. But they never physically touch.

mental activity such as directing attention, actually shape the structure of the brain?” As we’ve seen, experience means neural firing. When neurons fire together, the genes in their nuclei—their master control centers—become activated and “express” themselves. Gene expression means that certain proteins are produced. These proteins then enable the synaptic linkages to be constructed anew or to be strengthened. Experience also stimulates the production of myelin, the fatty sheath around axons, resulting in as much as a hundredfold increase in the speed of conduction down the neuron’s length. And as we now know, experience can also stimulate neural stem cells to differentiate into wholly new neurons in the brain. This neurogenesis, along with synapse formation and myelin growth, can take place in response to experience throughout our lives. As discussed before, the capacity of the brain to change is called neuroplasticity We are now discovering how the careful focus of attention amplifies neuroplasticity by stimulating the release of neurochemicals that enhance the structural growth of synaptic linkages among the activated neurons.

The four lobes we discussed are just the lobes of the cortex, the outermost layer of the brain. Underneath, the axons and dendrites connect and channel the billions of neurons above to each other and to deeper brain structures below.

I realized with fresh horror that new doors of perception were opening up inside. New? Not so. OLD doors of perception. The perception of a child who has not yet learned to protect itself by developing the tunnel vision that keeps out ninety percent of the universe. Children see everything their eyes happen upon, hear everything in their ears' range. But if life is the rise of consciousness…, then it is also the reduction of input. Terror is the widening of perspective and perception. The horror was in knowing I was swimming down to a place most of us leave when we get out of diapers and into training pants. I could see it on Ollie's face, too. When rationality begins to break down, the circuits of the human brain can overload. Axons grow bright and feverish. Hallucinations turn real: the quicksilver puddle at the point where perspective makes parallel lines seem to intersect is really there; the dead walk and talk; a rose begins to sing.

I can't stand how much like my dreams you smell; it's torture. You are torture. You wear metal on your skin like you're made of it, and it bites at me every time you're around. No matter how many showers I take, I smell your scent on me, on this ship, while I'm trying to sleep. I don't understand it, and can't stand it. I can't stand how I want you so badly and don't at the same time, because you're what I've been looking for, and I don't know what it means to have found it.

Work by Martha Farah of the University of Pennsylvania, Tom Boyce of UCSF, and others demonstrates something outrageous: By age five, the lower a child’s socioeconomic status, on the average, the (a) higher the basal glucocorticoid levels and/or the more reactive the glucocorticoid stress response, (b) the thinner the frontal cortex and the lower its metabolism, and (c) the poorer the frontal function concerning working memory, emotion regulation, impulse control, and executive decision making; moreover, to achieve equivalent frontal regulation, lower-SES kids must activate more frontal cortex than do higher-SES kids. In addition, childhood poverty impairs maturation of the corpus callosum, a bundle of axonal fibers connecting the two hemispheres and integrating their function. This is so wrong—foolishly pick a poor family to be born into, and by kindergarten, the odds of your succeeding at life’s marshmallow tests are already stacked against you.34

Ahora sabemos que el cerebro puede formar nuevos axones y dendritas hasta el final de la vida, lo que aumenta enormemente las esperanzas de poder prevenir la senilidad, por ejemplo, y de preservar nuestra capacidad mental de manera indefinida. (La capacidad del cerebro para crear nuevas conexiones es tan extraordinaria que un feto a punto de nacer forma unas 250.000 células cerebrales nuevas por minuto y, por tanto, millones de nuevas conexiones sinápticas en ese mismo período de tiempo).

In his research, Chamovitz discovered which genes are responsible for a plant’s ability to determine whether it’s in the dark or the light, and these genes, it turns out, are also part of human DNA. In animals, these same genes regulate responses to light and are involved in “the timing of cell division, the axonal growth of neurons, and the proper functioning of the immune system.” Analogous mechanisms exist in plants for detecting sounds, scents, and location, and even for forming memories.

Now to put in a flabbergasting real number: your average neuron has about ten thousand to fifty thousand dendritic spines and about the same number of axon terminals. Factor in a hundred billion neurons, and you see why brains, rather than kidneys, write good poetry.

And I did long for it, to say one true sentence of my own, to leap into the subject, that sturdy vessel travelling upstream through the axonal predicate into what is possible; into the object, which is all possibility; into what little we know of the future, of eternity--the light of which, incidentally, was streaming in on us just then through the high windows. Above Stasselova's head the storm clouds were dispersing, as if frightened by some impending goodwill, and I could see tht the birds were out again, forming into that familiar pointy hieroglyph, as they're told to do from deep within.

The connection between childhood adversity and frontocortical maturation pertains to childhood poverty. Work by Martha Farah of the University of Pennsylvania, Tom Boyce of UCSF, and others demonstrates something outrageous: By age five, the lower a child’s socioeconomic status, on the average, the (a) higher the basal glucocorticoid levels and/or the more reactive the glucocorticoid stress response, (b) the thinner the frontal cortex and the lower its metabolism, and (c) the poorer the frontal function concerning working memory, emotion regulation, impulse control, and executive decision making; moreover, to achieve equivalent frontal regulation, lower-SES kids must activate more frontal cortex than do higher-SES kids. In addition, childhood poverty impairs maturation of the corpus callosum, a bundle of axonal fibers connecting the two hemispheres and integrating their function. This is so wrong—foolishly pick a poor family to be born into, and by kindergarten, the odds of your succeeding at life’s marshmallow tests are already stacked against you.

I don’t get it.’ ‘You don’t have to. People don’t exist for us to get

During times of need, it was always the people with the least to give who ended up sacrificing the most.

The sensory cortex and visual cortex are far away from each other. How do those tactile neurons “know” (a) that there’s vacant property in the visual cortex; (b) that hooking up with those unoccupied neurons helps turn fingertip information into “reading”; and (c) how to send axonal projections to this new cortical continent? All are matters of ongoing research.

I feel as though dispossessed from the semblances of some crystalline reality to which I’d grown accustomed, and to some degree, had engaged in as a participant, but to which I had, nevertheless, grown inexplicably irrelevant. But the elements of this phenomenon are now quickly dissolving from memory and being replaced by reverse-engineered Random Access actualizations of junk code/DNA consciousness, the retro-coded catalysts of rogue cellular activity. The steel meshing titters musically and in its song, I hear a forgotten tale of the Interstitial gaps that form pinpoint vortexes at which fibers (quanta, as it were) of Reason come to a standstill, like light on the edge of a Singularity. The gaps, along their ridges, seasonally infected by the incidental wildfires in the collective unconscious substrata. Heat flanks passageways down the Interstices. Wildfires cluster—spread down the base trunk Axon in a definitive roar: hitting branches, flaring out to Dendrites to give rise to this release of the very chemical seeds through which sentience is begotten. Float about the ether, gliding a gentle current, before skimming down, to a skip over the surface of a sea of deep black with glimmering waves. And then, come to a stop, still inanimate and naked before any trespass into the Field, with all its layers that serve to veil. Plunge downward into the trenches. Swim backwards, upstream, and down through these spiraling jets of bubbles. Plummet past the threshold to trace the living history of shadows back to their source virus. And acquire this sense that the viruses as a sample, all of the outlying populations withstanding: they have their own sense of self-importance, too. Their own religion. And they mine their hosts barren with the utilitarian wherewithal that can only be expected of beings with self-preservationist motives.

The full sequence of communication between neurons is thus usually electrical-chemical-electrical: electrical signals coming down axons get converted into chemical messages that help trigger electrical signals in the next cell. There are also synapses through which communication between presynaptic and postsynaptic sites is purely electrical, but chemical transmission is the more prevalent form. Thus, much of what the brain does involves electrical-to-chemical-to-electrical coding of experience. As hard as it may be to imagine, electrochemical conversations between neurons make possible all of the wondrous (and sometimes dreadful) accomplishments of human minds. Your very understanding that the brain works this way is itself an electrochemical event.

Even more surprising—because we had been taught it was impossible—was that the axons from the resurrected retinal ganglion cell grew all the way from the back of the eye to a place near the center of the brain called the optic chiasm. “The amazing thing is that the regenerated axons were able to find their way home along these long, tortuous routes back to their targets in the brain . . . that’s incredible,” Huberman says.

The sympathetic nervous system (SNS) mediates the body’s response to arousing circumstances, for example, producing the famed “fight or flight” stress response. To use the feeble joke told to first-year medical students, the SNS mediates the “four Fs—fear, fight, flight, and sex.” Particular midbrain/brain-stem nuclei send long SNS projections down the spine and on to outposts throughout the body, where the axon terminals release the neurotransmitter norepinephrine.

This is the essence of learning. The lecturer says something, and it goes in one ear and out the other. The factoid is repeated; same thing. It’s repeated enough times and—aha!—the lightbulb goes on and suddenly you get it. At a synaptic level, the axon terminal having to repeatedly release glutamate is the lecturer droning on repetitively; the moment when the postsynaptic threshold is passed and the NMDA receptors first activate is the dendritic spine finally getting it.

Axonal remapping in blind or deaf individuals is great, exciting, and moving. It’s cool that your hippocampus expands if you drive a London cab. Ditto about the size and specialization of the auditory cortex in the triangle player in the orchestra. But at the other end, it’s disastrous that trauma enlarges the amygdala and atrophies the hippocampus, crippling those with PTSD. Similarly, expanding the amount of motor cortex devoted to finger dexterity is great in neurosurgeons but

A major push is under way to figure out the molecular basis of those "critical" or "sensitive" periods, to figure out how the brain changes as certain learning abilities come and go. In some, if not all, of those mammals that have the alternating stripes in the visual cortex known as ocular dominance columns, those columns can be adjusted early in development, but not in adulthood. A juvenile monkey that has one eye covered for an extended period of time can gradually readjust its brain wiring to favor the open eye; an adult monkey cannot adjust its wiring. At the end of a critical period, a set of sticky sugar-protein hybrids known as proteoglycans condenses into a tight net around the dendrites and cell bodies of some of the relevant neurons, and in so doing those proteoglycans appear to impede axons that would otherwise be wriggling around as part of the process of readjusting the ocular dominance columns; no wriggling, no learning. In a 2002 study with rats, Italian neuroscientist Tommaso Pizzorusso and his colleagues dissolved the excess proteoglycans with an antiproteoglycan enzyme known as "chABC," and in so doing managed to reopen the critical period. After the chABC treatment, even adult rats could recalibrate their ocular dominance columns. ChABC probably won't help us learn second languages anytime soon, but its antiproteoglycan function may have important medical implications in the not-too-distant future. Another 2002 study, also with rats, showed that chABC can also promote functional recovery after spinal cord injury.

Neuronal maturity doesn’t happen at the same pace across the human brain. Some regions are completed much earlier than others, and the frontal lobes are the last to receive the finishing touches. The prefrontal cortex of the brain, the most complicated region, which provides us with cognition and judgment, demands the most sculpting. The final step in making a neuron work optimally is to have the long axonal cables wrapped in a fatty insulation from the surrounding glia, a process called myelination. Only then is the brain fully grown.

But when you grew up, all that changed. You no longer lay awake in your bed, sure something was crouching in the closet or scratching at the window . . . but when something did happen, something beyond rational explanation, the circuits overloaded. The axons and dendrites got hot. You started to jitter and jive, you started to shake rattle and roll, your imagination started to hop and bop and do the funky chicken all over your nerves. You couldn’t just incorporate what had happened into your life experience. It didn’t digest. Your mind kept coming back to it, pawing it lightly like a kitten with a ball of string

Astounding, really, that Michel could consider psychology any kind of science at all. So much of it consisted of throwing together. Of thinking of the mind as a steam engine, the mechanical analogy most ready to hand during the birth of modern psychology. People had always done that when they thought about the mind: clockwork for Descartes, geological changes for the early Victorians, computers or holography for the twentieth century, AIs for the twenty-first…and for the Freudian traditionalists, steam engines. Application of heat, pressure buildup, pressure displacement, venting, all shifted into repression, sublimation, the return of the repressed. Sax thought it unlikely steam engines were an adequate model for the human mind. The mind was more like—what?—an ecology—a fellfield—or else a jungle, populated by all manner of strange beasts. Or a universe, filled with stars and quasars and black holes. Well—a bit grandiose, that—really it was more like a complex collection of synapses and axons, chemical energies surging hither and yon, like weather in an atmosphere. That was better—weather—storm fronts of thought, high-pressure zones, low-pressure cells, hurricanes—the jet streams of biological desires, always making their swift powerful rounds…life in the wind. Well. Throwing together. In fact the mind was poorly understood.

But when you grew up, all that changed. You no longer lay awake in your bed, sure something was crouching in the closet or scratching at the window ... but when something did happen, something beyond rational explanation, the circuits overloaded. The axons and dendrites got hot. You started to jitter and jive, you started to shake rattle and roll, your imagination started to hop and bop and do the funky chicken all over your nerves. You couldn’t just incorporate what had happened into your life experience. It didn’t digest. Your mind kept coming back to it, pawing it lightly like a kitten with a ball of string ... until eventually, of course, you either went crazy or got to a place where it was impossible for you to function.

Hebb's notion, as you'll recall, is that "when an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part in firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B, is increased." Let's expand this idea a little so we can see how it might apply to memory, and especially to a memory of the fact that two stimuli once occurred together. In order for two stimuli to be bound together in the mind, to become associated, the neural representations of the two events have to meet up in the brain. This means that there has to be some neuron (or a set of neurons) that receives information about both stimuli. Then, and only then, can the stimuli be linked together and an association be formed between them.

A recent comparative study looked at the neuropil volume in different areas of humans’ and chimps’ brains.43 Neuropil comprises the brain areas that are made of connections: a mixture of axons, dendrites, synapses, and more. The prefrontal cortex—the brain area in humans involved in decision making, problem solving, mental state attribution, and temporal planning—has a greater percentage of neuropil than is found in chimp brains, and the dendrites in this region have more spines with which they connect to other neurons than do other parts of the brain. This anatomical finding suggests that the connectivity patterns of the prefrontal neurons may contribute to what is different about our brains. Interestingly, corvids have a relatively larger forebrain than most other birds, especially the areas that are thought to be analogous to the prefrontal cortex of mammals.44 Yet, as we shall see, while this way of thinking may explain increased abilities, it is not going to get us to the goal of understanding how consciousness is enabled.

These axons can shuttle information around so quickly because they’re fatter than normal axons, and because they’re sheathed in a fatty substance called myelin. Myelin acts like rubber insulation on wires and prevents the signal from petering out: in whales, giraffes, and other stretched creatures, a sheathed neuron can send a signal multiple yards with little loss of fidelity. (In contrast, diseases that fray myelin, like multiple sclerosis, destroy communication between different nodes in the brain.) In sum, you can think about the gray matter as a patchwork of chips that analyze different types of information, and about the white matter as cables that transmit information between those chips. (And before we go further, I should point out that “gray” and “white” are misnomers. Gray matter looks pinkish-tan inside a living skull, while white matter, which makes up the bulk of the brain, looks pale pink. The white and gray colors appear only after you soak the brain in preservatives. Preservatives also harden the brain, which is normally tapioca-soft. This explains why the brain you might have dissected in biology class way back when didn’t disintegrate between your fingers.)

Finally, Tononi argues that the neural correlate of consciousness in the human brain resembles a grid-like structure. One of the most robust findings in neuroscience is how visual, auditory, and touch perceptual spaces map in a topographic manner onto visual, auditory, and somatosensory cortices. Most excitatory pyramidal cells and inhibitory interneurons have local axons strongly connected to their immediate neighbours, with the connections probability decreasing with distance. Topographically organized cortical tissue, whether it develops naturally inside the skull or is engineered out of stem cells and grown in dishes, will have high intrinsic causal power. This tissue will feel like something, even if our intuition revels at the thought that cortical carpets, disconnected from all their inputs and outputs, can experience anything. But this is precisely what happens to each one of us when we close our eyes, go to sleep, and dream. We create a world that feels as real as the awake one, while devoid of sensory input and unable to move. Cerebral organoids or grid-like substances will not be conscious of love or hate, but of space.; of up, down, close by and far away and other spatial phenomenology distinctions. But unless provided with sophisticated motor outputs, they will be unable to do anything.

A region of the brain becomes mature when it settles down into a lean, functionally well-organized system. A good proxy for neural pruning in the brain is the relative density of gray versus white matter in a given region. Gray matter, the neuron-rich part of the brain that does the bulk of the computational work, decreases in density as a region matures. As gray matter density decreases, the density of white matter—the myelinated axons that transmit information, the outputs of the computational work done by gray matter—increases, resulting in greater efficiency and speed but less flexibility. One way to envision this is to see an immature, gray-matter-rich region as an undeveloped, open field, where one can wander in many directions unconstrained, but not very efficiently. In order to get to that wonderful blackberry bush to harvest some fruit, I have to bushwhack my way through vegetation and ford streams. The gradual replacement of gray matter by white matter reflects the development of this field: As roads are laid and bridges are built, I can move around more easily and quickly, but now I’m going to tend to move only along these established pathways. The new paved road to the blackberry bush makes gathering blackberries much more convenient, but rushing along on the new road I will miss the delicious wild strawberries I would have otherwise stumbled upon in the brush. There is a trade-off between flexibility and efficiency, between discovery and goal achievement.

Cannabinoids relax the rules of cortical crowd control, but 300 micrograms of d-lysergic acid diethylamide break them completely. This is a clean sweep. This is the Renaissance after the Dark Ages. Dopamine—the fuel of desire—is only one of four major neuro modulators. Each of the neuromodulators fuels brain operations in its own particular way. But all four of them share two properties. First, they get released and used up all over the brain, not at specific locales. Second, each is produced by one specialized organ, a brain part designed to manufacture that one potent chemical (see Figure 3). Instead of watering the flowers one by one, neuromodulator release is like a sprinkler system. That’s why neuromodulators initiate changes that are global, not local. Dopamine fuels attraction, focus, approach, and especially wanting and doing. Norepinephrine fuels perceptual alertness, arousal, excitement, and attention to sensory detail. Acetylcholine energizes all mental operations, consciousness, and thought itself. But the final neuromodulator, serotonin, is more complicated in its action. Serotonin does a lot of different things in a lot of different places, because there are many kinds of serotonin receptors, and they inhabit a great variety of neural nooks, staking out an intricate network. One of serotonin’s most important jobs is to regulate information flow throughout the brain by inhibiting the firing of neurons in many places. And it’s the serotonin system that gets dynamited by LSD. Serotonin dampens, it paces, it soothes. It raises the threshold of neurons to the voltage changes induced by glutamate. Remember glutamate? That’s the main excitatory neurotransmitter that carries information from synapse to synapse throughout the brain. Serotonin cools this excitation, putting off the next axonal burst, making the receptive neuron less sensitive to the messages it receives from other neurons. Slow down! Take it easy! Don’t get carried away by every little molecule of glutamate. Serotonin soothes neurons that might otherwise fire too often, too quickly. If you want to know how it feels to get a serotonin boost, ask a depressive several days into antidepressant therapy. Paxil, Zoloft, Prozac, and all their cousins leave more serotonin in the synapses, hanging around, waiting to help out when the brain becomes too active. Which is most of the time if you feel the world is dark and threatening. Extra serotonin makes the thinking process more relaxed—a nice change for depressives, who get a chance to wallow in relative normality.

It’s now known that the brain can form new axons and dendrites up to the last years of life, which gives us tremendous hope for preventing senility, for example, and preserving our mental capacity indefinitely.

But knowing merely which neurons are connected with which is not enough. To create a brain emulation one would also need to know which synapses are excitatory and which are inhibitory; the strength of the connections; and various dynamical properties of axons, synapses, and dendritic trees.

Some neurons have short axons and some have exceedingly long ones, reaching clear from one side of the brain to the other. Placed end to end, the axons in your brain would stretch from Earth to the moon.

The recognition of the crucial roles played by these synaptic secretions drives us even further away from our electrical model and its reassuring familiarity. It is not a “spark” which jumps the gaps from neuron to neuron, it is a fluid, a chemical agent, a kind of enzyme or hormone. And when the gap is jumped, it is not a stream of electrons that is initiated on the surface of the membrane, it is a liquid solution containing sodium ions which surges back and forth through the membrane. Now these functional particulars are nothing at all like those of electrical wire; they remind us more of the secretion, circulation, and diffusion of all of the rest of our body’s fluids. A nerve is not a wire; it is more accurate to think of it as a tiny gland, with the axon serving as the duct. From the tip of this duct, secretions are released in small quantities and circulate to contact the target tissue—the next nerve in line. So neural activity has really as much to do with the laws of hydraulics as it does with the laws of electricity. The action potential is the movement of fluids. It is only like an electrical signal in certain respects.

In still higher invertebrates, such as the earthworm, the diffuse nature of this intermediate net disappears, and it is now organized into a distinct nerve cord running the length of the worm. Sensory elements become even more differentiated, and the special senses—light sensitivity, smell, taste, gravitational orientation—become even more concentrated at the head end, swelling the size, capacity, and sophistication of the head ganglion even further. The sensory elements still originate in the worm’s skin, but now they send their axons directly to the central cord, without contacting any muscle cells; and for the first time distinct motor neurons appear, sending their axons out from the central cord to the muscle cells in the body. And in addition, we encounter another type of nerve cell for the first time, cells which are contained wholly within the head ganglion and the cord, cells which are neither really sensory nor motor, at last purely internuncial in their functions. They are arranged into afferent and efferent pathways, running the length of the cord towards and away from the head ganglion.

The pathways with axons pointed towards the core, and which carry impulses inward, are called the afferent pathways. They originate in the various sensory endings of the body—the exteroceptors on the surface, the proprioceptors in the connective tissues (especially the joints), and the interoceptors in the the internal organs. Their final axons terminate in the sensory cortex. They are often referred to as the sensory pathways. Their job is to carry to all the levels of the nervous system information about everything that is affecting the organism—that is, all sensory stimulation. Four of these afferent pathways are short and distinct, arising from the highly localized and specialized areas of the “special senses”—sight, hearing, taste, and smell. The fifth kind of sensory information, that wide array of sensations we refer to collectively as “touch,” converges on the cortex from virtually every surface and cranny of the body. These are the “somatic senses,” and they include all of the pathways and endings which inform us of our internal state of affairs and our relationship to the outside world. The afferent, inflowing pathways of the nervous system constitute one of the principal tools of bodywork. It is by their means that surface contact and pressure enter into the deeper strata of the mind, where genetic potential and sensory experience are fused into behavior and character. Each successive afferent neuron is a finger reaching deeper and deeper into the interior, making its influence felt on all levels which influence behavior. It is sensory input which has conditioned our reflexes, postures, and habits into the patterns in which we find ourselves living. Nothing would seem to be more reasonable than the expectation that different sensory input can recondition these habits and patterns, alter them, improve them. This input can be different both in the sense of being more, giving additional nutritive contact to the various subtle degrees of “deprivation dwarfism,” and in the sense of being more pleasurable, more caring, softening and dissolving compulsive patterns that have been created by pain and stress.

The pathways with axons pointed towards the periphery, and which conduct impulses outward, are called efferent pathways. Their origins can ultimately be traced to the motor cortex, next to the sensory cortex at the top of the brain. Their axons descend the spinal cord and fan out into the body, terminating in synapses with the striated skeletal and cardiac muscles, and the smooth muscles of the vessels, internal organs, and glands. They are alternately termed the motor pathways. Their role is to carry out to the body, from every level in the nervous system, all of the impulses which control the appropriate contraction and lengthening of the entire musculature. Their signals are translated into the various behavioral effects which the mind chooses in response to input.

Because the efferent pathways lead directly to muscle cells, it is tempting to regard their activities as the cause of our motor behavior. But they are nothing of the kind until they are themselves stimulated by their numerous connections with the spinal cord and the brain (remember that an estimated fifteen thousand axons can converge upon a single terminal motor neuron). And these deeper, more central activities are in turn initiated and directed to a large degree by afferent, sensory stimulation. In bodywork, it is often problematical aberrations of motor response that we want to change, but sensory affects are our only means of doing so. We know we are doing our job when our hands feel jumpy reflexes smoothing out, high levels of tone decreasing, pliability returning to stiffened areas, range of motion increasing. These are all quantitative and qualitative shifts in motor activity. But we also must know that it is only our skilled manipulation of sensory stimulation which can accomplish these things, because it is primarily sensory associations which have conditioned the muscular patterns in the first place. Until the body feels something different, it cannot act differently. Only when contact with the world is perceived as something other than jabs and buffets can the organism respond with something other than aggression and defense.

In this regard, the delicate cell bodies, dendrites, and axons are like the many other fluid-filled tubes within the body. The quality of their function is susceptible to changes in pressure, distortion, viscosity. Their need for constant irrigation is acute: If fresh oxygen is held back from a neuron for merely three to five seconds, it is rendered completely unexcitable.4 And necessary substances must circulate inside the cell as well as around it. If a long dendrite or axon is pinched, closing its length off from the rest of the cell’s fluid, the excitability of the isolated branch quickly decays and eventually the pinched axon or dendrite will atrophy. You can park a truck on top of an electrical wire and it will continue to work nicely. It will work, in fact, until it is completely severed. In contrast there are many intermediate stages of malfunction in a nerve short of this final breakage—or lesion—most of them having to do with the relative effectiveness of the delivery and circulation of nutritional fluids and the adequate flushing of toxins and wastes. These intermediate malfunctions do not normally stop the system; they just make it less efficient. They confuse sensations, cloud thoughts, disturb the precision of our muscular efforts, make us numb in some spots, unaccountably sensitive in others, eliminate responses, force compensations. Insofar as effective bodywork can be of direct benefit to the circulation of bodily fluids, it can help to support the actual metabolic bases of nerve function, and this benefit is above and beyond the question of the value of any actual sensations it may produce.

The glial cells support every neural fiber, collect these fibers into bundles, and separate these bundles from the surrounding tissues and fluids. They give the nerve fibers the tensile strength and elasticity to stretch where stretching is needed, and they fix the nerve bundles securely to other structures where stability is needed. This surrounding glial tissue also comprises the ground substance for the intercellular metabolic activities attendant to the needs of the neurons, mediating the interchange of nutrition, gases, hormones, and waste products between nerves and capillaries, and carrying the white blood cells, antibodies, and other immune factors which guard the lives of the irreplaceable neurons. Other specialized glial cells—oligodendrocytes and Schwann cells—insulate the long axons with a tough, fatty coating called myelin. This insulation prevents signals from one axon inadvertently “leaking” into adjacent axons, and it also speeds up the passage of a neural impulse considerably. Myelin is whitish in color, giving the so-called “white matter” of the nervous system its name. “White matter” contrasts to “grey matter.” the color of cell bodies and axons that are not coated with myelin sheaths.

At the peripheral end of these parallel circuits, the motor nerve axon attaches to a muscle cell by a motor end plate, creating a neuromuscular synapse. Each muscle cell receives one, and only one, end plate. Each motor axon, on the other hand, has a number of branches and attaches end plates to several different muscle cells in the same area. So each muscle cell receives commands from one nerve cell only, while each nerve cell stimulates several muscle cells. A single motor neuron with its group of attached muscle cells is called a motor unit.

Efferent impulses may be conducted along one of two major pathways of motor neurons as they pass from the brain through the cord and out to the muscles, and together these longitudinal pathways provide for the convergence of the influences from all levels of the central nervous system upon the motor units. The fastest of these descending routes is the direct corticospinal pathway. As the name suggests, the cell bodies of this path are in the cortex, and they send their long axons directly through the brain and down the spinal cord without any interruptions. These axons do not form any synapses until they reach their corresponding motor neurons in the cord, and thus they form direct connections between specific cells in the motor cortex and specific motor neurons at each level of the cord, making one-to-one relationships between cortical cells and peripheral motor units. This pathway bypasses most of the intermediate circuitry of the lower brain and the spinal cord. This gives it the advantage of speedy transmission. The axons which are bundled together within it maintain a constant spatial relationship throughout their length, faithfully reflecting the spatial relationships of the cell bodies in the cortex. The longest axons, reaching all the way to the end of the cord, lie the closest to the center of the cord, and the progressively shorter axons which synapse to motor neurons in progressively higher segments, are carefully laid down in layers progressively far from the center of the cord, so that a “map” of skeletal muscle relationships is projected onto the motor cortex. This gives a high degree of specificity to this direct corticospinal tract. This direct pathway is the mediator of fine, intricate movements, which require close conscious attention and constantly refined adjustment. When it is severed, actions become clumsier, because the sharp edge of delicate conscious control is missing.

Dorsal The dorsal column system runs through the “white matter” of the spinal cord. It is white because its axons are insulated with white, fatty myelin, which increases their transmission speed considerably. Their speed—from forty to seventy meters per second—is also enhanced by the fact that there are few synapses to cross from the peripheral sensory ending to the cortex. Like the corticospinal motor pathway, these fibers have a high degree of spatial organization throughout the length of the spinal cord, and like the corticospinal pathway, they faithfully map the relationships of their origins onto the cortex. This system transmits touch sensations which have precise localizations and fine gradations of intensity, phasic or vibratory sensations, kinesthetic sensations related to body parts in motion, and sensations which have to do with fine distinctions of pressure.

The spinothalamic system, on the other hand, runs through the “grey matter” of the cord, so named because it has no white fatty insulation sheaths around its axons. Their spatial orientation is not nearly so carefully preserved at all levels, and they make many more internuncial synaptic junctions on their way up the cord. Their transmission speed is roughly one-fifth of that of the dorsal tract. This system carries impulses which announce pain; thermal sensations, both hot and cold; crude touch sensations that are not acutely localized; pressure sensations that do not rely upon fine distinctions; kinesthetic sensations having to do with chronic conditions, or the body at rest; tickles and itches; and sexual sensations. It is a fact of considerable significance to our reflex responses that pain sensations are carried exclusively by the slower spinothalamic pathway. This means that more neutral and at the same time more detailed sensory information will always reach the spinal circuits and the cortex slightly before the stab of pain arrives. This gives us a brief moment to assess the location and the cause of the pain before we react, so that our reflex withdrawal can be more appropriately tailored to the actual source of the pain and more effectively directed; that is, so that we will be able to assess the intensity of the burn, and will be sure to jerk away from the flame rather than towards it, and will arrest our jerk before we crash into the wall. This time lag gives a special role to general tactile sensations—including body work—when we are in pain. It means that it is possible to bombard the consciousness with more rapidly transmitted and more detailed touch sensations which tend to displace the pain response from the foreground. This is why rubbing the spot that hurts, or jumping up and down, or shaking the injured hand are often effective for alleviating pain. This is the principle behind the mother’s instinctual rocking and stroking of her hurt child, and it is a principle that can be turned to great advantage in bodywork. If the rest of the body can be inundated with touch sensations, particularly pleasurable ones, the part that is in pain can be shifted away from the mind’s central focus. On the other hand, this very same mechanism presents a danger: By keeping ourselves busy, and by forcing our attention onto other matters, it is possible to suppress pain signals which may be very important, possible to bury our awareness of threatening conditions beneath a layer of faster, more acute, but more trivial sensations. The mind’s mechanisms of selection and focus can play tricks that are nasty as well as ones that are helpful. One of the principal strengths of bodywork is that it can generate the sensory information—the self awareness—that is necessary for the individual to identify and gain control over conflicting tendencies of this kind.

The Golgi organs themselves are multi-branched type endings of sensory axons, which are woven among the collagen fibers near the muscle cells, and which are stimulated by the straightening and recoiling of the tendon. As is the case with the muscle spindles, the stimulation of a single tendon organ is highly specific: Each particular organ is most directly affected by the lengthening and contracting of the few alpha muscle fibers which attach to the collagen bundles containing that tendon organ, so that each Golgi is responsive to the activities of only ten to fifteen alpha motor units.

There is another way of separating the whole system into major divisions, divisions which are not as visually obvious as peripheral and central, but which in some ways more accurately represent actual functional distinctions. Roughly half of our neurons have their dendrites reaching out towards the surfaces of our organisms, and their axons reaching in towards the core. This means that they propagate their action potentials in an inward—centripetal—direction. The other half are arranged with their dendrites reaching in towards the core and their axons reaching out towards the periphery; these neurons send their action potentials in an outward—centrifugal—direction. The pathways created by these differently oriented neurons do not stop at the threshold of the central nervous system; both can be traced from the periphery to the spinal cord, throughout the cord’s length, through the brainstem and the hypothalamus, and finally to the literal summit of the brain, the sensory and motor cortexes. This division is based, then, not on the separation of these different anatomical structures, but upon the direction of action potential flow through those structures and the specific pathways they take.

The lower brain—including the pons and the brain stem—is primarily responsible for our “subconscious” processes, those many activities which are more complex and integrated than cord reflexes, but of which we are seldom aware. To begin with, many more sequences of simple reflexes are possible if the pons and the stem are left intact with the cord. The lower brain clearly assists the cord in fine-tuning responses, and in arranging them in the appropriate order so that they produce more integrated behavior. The complicated sequences of muscular contraction necessary for sucking and swallowing, for example, are monitored at this level. These are skills with which a human infant is born; their underlying circuits—and even more importantly, the correct sequence of operation of these circuits—is a product of early genetic development, not individual experience and learning. In general, the lower brain seems to share many of the “hard-wired” features of the spinal cord. Axons and synapses form organizational units that appear to be consistent for all individuals of the same species, and their activation produces identical, stereotyped contractions and motions. But the additional complexities of the lower brain appear to enable it to pick and choose more freely among various possible circuits, and to arrange the stereotyped responses with a lot more flexibility than is possible with the cord alone. For instance, it is in the lower brain that information from the semi-circular canals in the inner ear—the sensory organ for gravitational perceptions and balance—is coordinated with the cord’s postural reflexes. A stiff stance can be elicited from these postural reflexes by merely putting pressure on the bottoms of the feet; by adding information concerning gravity and balance to this stance, the same reflex cord circuits may be continually adjusted to compensate for shifts in equilibrium as we tilt the floor upon which the animal is standing, or as we push him this way or that. A rigid fixed posture is made more flexible and at the same time more stable, because compensating adjustments among the simple postural reflexes is now possible. The lower brain coordinates the movements of the eyes, so that they track together. It directs digestive and metabolic processes and glandular secretions, and determines the patterns of circulation by controlling arterial blood pressure. And not only does it give new coordination to separate parts, it influences the system as a whole in ways that cannot be done by the segmental arrangement of the cord.

The sensory axon that ends in the anulospiral receptor reaches out from its cell body located in the spinal cord. This cell body synapses with its own spinal sensory tracts which carry the spindles’ sensory information up each segment of the spinal column and finally to the brain, much like the orderly, parallel spinal tracts for the skin receptors, the joint receptors, and so on. But in addition to joining together in its own sensory stream like all other sensory nerves headed for the brain, the cell bodies of the anulospiral receptors make another interesting connection within the spinal column. They synapse directly to the body of a motor nerve as well, and to precisely the motor nerve which stimulates the skeletal muscle cells that surround the corresponding spindle. This means that the terminal motor nerve, the one which directly excites the muscle cells of the skeletal motor unit, can be excited not only by motor commands from the brain, but can also be excited by a sensory signal from the muscle spindle surrounded by the muscle cells of the same skeletal motor unit. 7-7: A simple spindle reflex arc. A single afferent nerve forms the anulospiral receptor at one end and synapses directly to a motor nerve at the other end, in the spinal column. This motor nerve in turn synapses to muscle cells in the immediate vicinity of the spindle, creating a very sensitive local feedback loop. This sensory-to-motor synapse in the spinal cord forms a reflex arc, the most direct linkage we have between local sensory events and local motor response. Activity in specific muscle cells creates a local sensory impulse which directly effects the subsequent activity of the same muscle cells. Thus the reflex arc constitutes a feedback loop which both keeps my muscles themselves constantly informed as to what they are up to, and constantly modifies their efforts. And most of this feedback takes place in the spinal cord, far below my levels of conscious awareness, and far more rapidly than I could consciously command it.

It has long been known that interoceptive signals are largely conveyed to the central nervous system either by neurons whose axons are devoid of myelin, the C fibers, or by neurons whose axons are very lightly myelinated, the A delta fibers.

Diffusion tensor imaging (DTI), or tractography, is an in vivo MRI technology that uses water diffusion in brain tissue to visualize in stunning detail the brain's three-dimensional white matter anatomy. DTI is made possible by characterizing water diffusion in tissues by means of a mathematical tool called a tensor, based on matrix algebra: (1) a 3 x 3 matrix, called a diffusion tensor, is used to characterize the three-dimensional properties of water molecule diffusion; (2) from each diffusion tensor, the three pairs of eigenvalues and eigenvectors are calculated using matrix diagonalization; and (3) the eigenvector that corresponds to the largest eigenvalue is selected as the primary eigenvector. A 'streamline' algorithm then creates "tracts" by connecting adjacent voxels if their directional bias is above some treshold level. Does the orientation of the primary eigenvector coincide with that of the actual axon fibers in most white matter tracts ? Takahashi et al. (2011), for example, have demonstrated that radial organization of the subplate revealed via tractography directly correlates with its radial cellular organization, and G. Xu et al. (2014) were able to determine that transient radial coherence of white matter in the developing fetus reflected a composite of radial glial fibers, penetrating blood vessels, and radial axons.

More than three hundred and two,” said Desh wryly. “One hundred billion,” said Kira emphatically. “One hundred billion! And on the order of one hundred trillion synaptic connections between them. Not to mention two million miles of axons. Electrical signals are constantly zipping along neuronal pathways like pinballs, creating thought and memory. The possible number of neuronal pathways that can be formed by the human brain are basically infinite. And a computer uses base two. A circuit can either be on or off; one or zero. But your brain is far more nuanced. The number of possible circuits your brain can use for calculation, or thought, or invention, puts the possible number available to computers to shame.” “Okay,” said Desh, nodding toward her

Hebb’s rule, as it has come to be known, is the cornerstone of connectionism. Indeed, the field derives its name from the belief that knowledge is stored in the connections between neurons. Donald Hebb, a Canadian psychologist, stated it this way in his 1949 book The Organization of Behavior: “When an axon of cell A is near enough cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.” It’s often paraphrased as “Neurons that fire together wire together.

You're a hacker. That means you have deep structures to worry about, too." "Deep structures?" "Neurolinguistic pathways in your brain. Remember the first time you learned binary code?" "Sure." "You were forming pathways in your brain. Deep structures. Your nerves grow new connections as you use them -- the axons split and push their way between the dividing glial cells -- your bioware selfmodifies -- the software becomes part of the hardware. So now you're vulnerable -- all hackers are vulnerable -- to a nam-shub. We have to look out for each other." "What's a nam-shub? Why am I vulnerable to it?" "Just don't stare into any bitmaps. Anyone try to show you a raw bitmap lately? Like, in the Metaverse?" Interesting. "Not to me personally, but now that you mention it, this Brandy came up to my friend --" "A cult prostitute of Asherah. Trying to spread the disease. Which is synonymous with evil. Sound melodramatic? Not really. You know, to the Mesopotamians, there was no independent concept of evil. Just disease and ill health. Evil was a synonym for disease. So what does that tell you?

We've taken a small part of how our brain works - the patterns of dendrites and axons and synapses - and we've built computer architectures around them. But that's all it is - a symbolic machine inspired by the human brain. Real brains are biological pieces of meat inextricably connected to the bodies that host them and the environments they inhabit in a million essential ways. A computer is a complex tool, but it's not a brain. It requires the human operator to be its body, to be its environment, by writing its algorithm and feeding it data. If we really want to make an artificial construct that can think like we do, we have to start over with a completely different concept.

I began lamenting the terrible social consequences of materialism and my view that the less-than-laudable moral condition of America in general and Santa Cruz in particular (I was grumpy from overwork and have never been particularly enamored of the moral condition of Santa Cruz in any event) could be laid at the feet of nearly three centuries of materialist ascendancy. The reigning belief that the thoughts we think and the choices we make reflect the deterministic workings of neurons and, ultimately, subatomic particles seemed to me to have subverted mankind’s sense of morality. The view that people are mere machines and that the mind is just another (not particularly special) manifestation of a clockwork physical universe had infiltrated all our thinking, whether or not someone knew a synapse from an axon. Do you know what the most addressable cause of all this moral decrepitude is?, I asked Dave. Materialism! Not the materialism of Rodeo Drive, SUVs, and second homes in Telluride, but materialism as a worldview, a view that holds that the physical is all that exists, and that transcendent human mental experiences and emotions, no matter what grandeur they seem—from within—to possess, are in reality nothing but the expressions of electrical pulses zipping along neurons. Chalmers wouldn’t be the first (or the last) to express incredulity that I was blaming the moral morass of the late twentieth century on a school of philosophy that most people had never heard of.

Applying quantum theory to the brain means recognizing that the behaviors of atoms and subatomic particles that constitute the brain, in particular the behavior of ions whose movements create electrical signals along axons and of neurotransmitters that are released into synapses, are all described by Schródinger wave equations. Thanks to superpositions of possibilities, calcium ions might or might not diffuse to sites that trigger the emptying of synaptic vesicles, and thus a drop of neurotransmitter might or might not be released. The result is a whole slew of quantum superpositions of possible brain events. When such superpositions describe whether a radioactive atom has disintegrated, we say that those superpositions of possibilities collapse into a single actuality at the moment we observe the state of that previously ambiguous atom. The resulting increment in the observer’s knowledge of the quantum system (the newly acquired knowledge that the atom has decayed or not) entails a collapse of the wave functions describing his brain.

Axons and dendrites enable neurons to wire up with a connectivity that computer designers can only fantasize about. Each of the 100 billion neurons connects to, typically, anywhere from about a few thousand to 100,000 other neurons. The best guess is that, at birth, each neuron makes an average of 2,500 of these specialized junctions, or synapses; reaches a connectivity peak of 15,000 synapses at age two or three; and then starts losing synapses in a process called pruning. If we take a conservative mean for the number of connections (1,000), then the adult brain boasts an estimated 100,000,000,000,000—100 trillion—synapses. Other estimates of the number of synapses in the adult brain go as high as 1,000 trillion.

The linear size of a neuron varies widely from one nerve cell to the other, since some of these cells are contained in closely integrated large aggregates and have, therefore, very short axons, while others conduct pulses between rather remote parts of the body and may, therefore, have linear extensions comparable to those of the entire human body.

It’s not the loneliness that lengthens the cracks. In the long run, it’s the isolation. --Axon Drift

It’s not the loneliness that lengthens the cracks. In the long run, it’s the isolation. -Bibiana Krall, Axon Drift

In many ways, this chemical medium behaves like the human sexual response. Sexual arousal and recovery depend on the properties of nerve tissue, which, like Zhabotinsky soup, belongs to a general class of systems called excitable media. A neuron has three states: quiescent, excited, and refractory. Normally a neuron is quiescent. With inadequate stimulation, it shows little response and returns to rest. But a sufficiently provocative stimulus will excite the neuron and cause it to fire. Next it becomes refractory (incapable of being excited for a while) and finally returns to quiescence. The parallels with chemical waves extend to action potentials, the electrical waves that propagate along nerve axons. They too travel without attenuation, and when two of them collide, they annihilate each other. In fact, all of these statements are equally true of electrical waves in another excitable medium: the heart. That’s the beauty of this abstraction—the qualitative properties of one excitable medium hold for them all. They can all be studied in one stroke.

1) Neuroline - synthetic axonal growth in the white and grey matter of the brain and spinal column, allowing for significant improvements in mental faculties while a User’s Cognition spec is applied.

Receptor neurons bundle together into cables called axons, feeding up through holes in a perforated bone just behind the eyeballs called the cribriform plate. (In a serious head injury, the skull can shift, and the lateral movement of the cribriform plate shears those axons like a knife through spaghetti. Snip! No more sense of smell.) Once through the plate, the axons connect to two projections from the brain called the olfactory bulbs. There, in blobs of neurons called glomeruli, is where the bulk of the computation gets done. Mice, known for their acute sense of smell, have just about 1,800 glomeruli—but 1,000 genes that code for olfactory receptors. That’s a lot of perceivable smells. Humans have a seemingly pathetic 370 genes for receptors, but we have 5,500 glomeruli per bulb. That’s a lot of processing power. It must be doing something. The part of the brain that integrates all this information, the olfactory cortex, also gets inputs from the limbic region and other areas that deal with emotion—the amygdala and hypothalamus, among others. Processing of smells in the brain, then, is tied to not only the chemical perception of a molecule but also how we feel about it, and how we feel in general. Every other sense in the body is, in a way, indirect. In vision, light impinges on the retina, a sheet of cells at the back of the eye that makes pigments and connects to the optic nerve. In hearing, sound (which is really just waves of changing air pressure) pushes the eardrum in and out at particular frequencies, which translate via a series of tiny bones to nerves. Touch and taste are the same. Some cell, built to do the hard work of reception, gets between the stimulus and the nerves that lead to the brain for processing. Some physical effect—air pressure, reflected photons, whatever—gets between the stimulus and the perception. It’s all a first-order derivative. Not smell, though. When we smell something, we are smelling tiny pieces of that thing that have broken off, wafted through the air, and then touched actual neurons wired to actual pieces of brain. Olfaction is direct, with nothing between the thing we’re smelling, the smell it has, and how we perceive that smell. It is our most intimate sense.

Dendrons of Dynamite, Axons of Asphalt, Corazón de Kevlar - That's how we move the world, That's how we emerge as humanizer.

You and I might have smidgens of autism and not realize it, especially if you happen to be a man. Scientists have sometimes described autism as an extreme version of the male brain. And in truth, of all the world’s autistics, only one fifth are female.3 This may be because women have more axons and dendrites, which are the pathways in the brain that enable it to work as a unit. Men’s brains have more neurons. In effect, this makes male brains less networked than women’s, but outfitted with more processing power, largely focused, it seems, on spatial and temporal capabilities. This doesn’t make one sex smarter or more talented than the other, simply different. It also helps explain, at least according to some scientists, why men are sometimes less socially tuned in than females, and why women are superior, generally, at reading social cues.

If you are standing still and decide to take a step, the movement of your leg on the basis of your decision involves axons that originate in cell bodies located in the movement control regions in the frontal cortex (just behind your forehead) and that travel uninterrupted to the base of the spinal column (in the region of your lower back).

The brain is essentially an oddly shaped sphere of Jell-O, crammed inside a box, covered in a shallow layer of cerebrospinal fluid. This gelatinous material contains a kind of electrical grid—hooked up to an EEG, the brain can power a toy train—that transmits information through the body via microscopic fibers called axons. When someone is hit in the head or stops suddenly, the brain is jolted against the skull’s jagged interior, distorting or even severing the axons and interrupting the function of the synapses, the connections between the fibers of the brain.

Mental challenges cause an “adaptive response” to take place in the brain, just like a muscle. Challenges build axon-dendrite “transmitter-receiver” connections. Passive activities such as watching “reality” television do not stimulate or build these connections. We need to be actively involved with our activities, instead of being passive observers. Making and unmaking nerve cell connections (neuroplasticity) dictates how well the brain can handle stress.

At least one version of quantum theory, propounded by the Hungarian mathematician John von Neumann in the 1930's "claims that the world is built no out of bits of matter but out of bits of knowledge-subjective, conscious knowings," Stapp says. These ideas, however, have fallen far short of toppling the materialist worldview, which has emerged so triumphant that to suggest humbly that there might be more to mental life than action potentials zipping along axons is to risk being branded a scientific naif. Even worse, it is to be branded nonscientific. When, in 1997, I made just this suggestion over dinner to a former president of the Society for Neuroscience, he exlaimed, "Well, then you are not a scientist." Questioning whether consciousness, emotions, thoughts, the subjective feeling of pain, and the spark of creativity arise from nothing but the electrochemical activity of large collections of neuronal circuits is a good way to get dismissed as a hopeless dualist.

During the twentieth century, neuroscientists and psychologists also came to more fully appreciate the astounding complexity of the human brain. Inside our skulls, they discovered, are some 100 billion neurons, which take many different shapes and range in length from a few tenths of a millimeter to a few feet.4 A single neuron typically has many dendrites (though only one axon), and dendrites and axons can have a multitude of branches and synaptic terminals. The average neuron makes about a thousand synaptic connections, and some neurons can make a hundred times that number.

Now we saw that when you put motor and sensory nerves together into a reflex arc, the current flow formed an unbroken loop. This solved the mystery of what completed the circuit: The current returned through nerves, not some other tissue. Just as Gerard had found in the brain,nerves throughout the body were uniformly polarized, positive at the input fiber, or dendrite, and negative at the output fiber, or axon. We realized that this electrical polarization might be what guided the impulses to move in one direction only, giving coherence to the nervous system.

Noyé par les affres entreposées, l'oxygène, pur, inexistant de mes axones. Délivré par une manque de contact humain, consommé par des choix incandescentes. Consommé par la vie, l'amour et la perte.

Paradise is murder.

Unassembled at Birth Children are not born with fully connected brains ready to process the world. They are born with their brains unassembled. Imagine buying a computer, opening the box, and finding only a bag of parts. This is analogous to the child’s brain at birth: at birth newborns have 100 billion brain cells — the brain cells they will have for their entire life. But these cells are not connected. Newborns do not see Mom, Dad, sister, or brother. For them, it’s not an integrated picture: head, neck, shoulders. They don’t hear smooth, sequential sounds. The baby’s senses are assaulted by disconnected, constantly changing lights and sounds. The brain circuits needed to process experience are simply not there yet. Natural increase in number of connections Luckily, the newborn’s brain knows exactly what to do; it’s in the DNA. The brain begins a well-orchestrated process of first increasing the number of connections between brain cells or neurons, and then after 5 to 6 years eliminating the ones not used and keeping those that were used. Take a look at Figure 2.1, which shows magnified sections of the surface of the brain, the cortex. The cortex integrates all our sensations into conscious experiences. This is a hand drawing from a Golgi stain of the cortex from Conel. In reality, the cortex is the thickness of a nickel. This particular figure shows the connections in Broca’s area, just above and behind the temples, where speech is produced. Each triangle represents a cell body, which controls and directs the activity of the neuron; the lines are dendrites (input fibers) and axons (output fibers) that connect the neurons.

Figure 3.3 Astrocytes maintain the structure of the synapses. In addition, the astrocytes maintain the 20 nanometer wide space between the axon terminal from one cell (output) and the dendritic spines of another cell (input). This space is called the synapse. How is this very thin space maintained? Why doesn’t the axon terminal float away? Or glide into the dendritic spine? Notice in the figure the ends of the astrocyte envelop the synapse and maintain its integrity. The astrocyte both encircles the axon terminal and the dendritic spine and maintains the optimal distance between them. (We discuss the dynamics within the synapse later.) This serves to isolate the synapse from the space around the neuron, and so limits the dispersion of transmitter substances released by the axon terminal into the extracellular space. Children are not just small adults Now you can understand why children are not just small adults. Children’s brain connections are different than adults, and so children necessarily process the world in a different way than their parents. Figure 3.4 below shows brain images (heads are facing to the left) when children and adults were given the same task — a “noun/verb” task. They heard a noun, such as car, and generated a verb. What verb might you generate for the word car? Drive. For the word bike? Ride. For the word food? Eat. Notice, children perform this task by primarily using the back of the brain (right of the figure). This is the visual association area, the area that creates concrete perception. When adults did this task, the most active parts of the brain were in the front (right of the figure).

All boundaries are challenged by those that neighbour them. Even divides as certain as truth or fiction become fraught on close inspection. The library contains novels written in the style of a historian, leading the unwary down rabbit holes into imaginary pasts wherein sabbers built great cities and dwelt within them, aping the habits of man. Obviously, such flights of fancy are unlikely to mislead any but the most foolish reader, but other variations on the truth may be sufficiently plausible to trick even the most erudite. Know Your Library, by Axon Bloom

The future belongs to the daughters of defiance

The future belongs to the daughters of defiance.

Many people with ADD have noticed that a strange drowsiness may come over them in the midst of some emotionally charged situations, as, for example, during a conflict with a spouse. All of a sudden, they start yawning and their eyelids grow heavy. Their partners naturally believe that the drowsiness is a sign of boredom and a lack of caring. Or the emotionally stressed ADD child may suddenly—and genuinely—complain of being “tired,” only to regain energy a few minutes later if the source of anxiety, which may be some homework she feels beyond her capacities to do, is removed. The parent may conclude that the child is malingering. What is really happening is that the right prefrontal cortex is over-inhibiting a network of neurons in the brain stem, known as the reticular_formation-an important part of the circuitry of arousal—because the emotions are too threatening. The reticular formation sends axons (nerve cables) to the cortex, where chemicals are released that make the cortical cells more alert, more responsive to incoming information. The cortex, in turn, projects axons to the reticular formation and can inhibit its arousal function, as in the case of our drowsy individual or the tired child. For the person in emotional distress, drifting off to sleep would permit at least a temporary escape—an unconscious defense closely connected with tuning out.

The physics of diffuse axonal injury Given our understanding of the rotational nature of diffuse axonal injury, it is now possible for us to take what we learned about levers and rotational motion in the previous chapters and apply that knowledge here to help us understand how a punch to the chin ends up stretching and damaging axons in the brainstem and throughout the brain. The first step in this process is the punch. This punch must meet a minimum energy requirement because we will be causing structural damage to axons in the brain. This punch must also meet a minimum momentum requirement because we need to spin the whole head around to damage those axons. Considering what we know about knockout punches and how boxers train, it is relatively safe to say that meeting the minimum energy requirement is not difficult, but meeting the minimum momentum requirement is. Fast punches are important strategically, but increasing the effective mass behind your punches is what gives your punch the ability to lay your opponent out on the mat. Figure 5-2. The process of diffuse axonal injury from punch to axon stretching. Left: The punch hits your opponent. Center: The punch rotates your opponent’s head around an axis located in the neck. Right: Axons located a small distance from the axis of rotation become stretched as one end of the axon travels around the axis of rotation. This story takes us from the fist to the axon, but there is still something missing. We turn our heads left and right every day, sometimes very rapidly, so what makes a punch so special? The science is still too young to be sure, but I will speculate that the peak of the force curve (figure 5-3) is typically where the axon gets rapidly extended to its natural limit, but the tail of the force curve is where the axons are damaged. The primary reason for this speculation is the empirical knowledge that pushing off the back foot is essential for a good knockout punch. Boxers and martial artists from all styles stress the importance of this push to the success of a punch. Some strikes, such as a front-hand palm strike or a square-shouldered wing chun punch, for which a back-foot push is impossible, will still generate the same long-tail force profile in figure 5-3 by making contact before the arm is fully extended and using the muscles in the arm to apply force by continuing the extension. The same profile appears when athletes tackle each other in other contact sports. There is an initial peak force at the moment of collision, but the legs continue to push after the initial peak.

The neck is also a viable target. Given our understanding of diffuse axonal injury as the result of stretching forces on the axons in the brain (particularly near the base of the skull), it is reasonable to assume you could generate the same damage by applying a force on either side of the same axon. Since it appears that knockouts occur as a result of diffuse axonal injury involving the brainstem (Smith, et al., 2000), we should be able to apply our force to the neck to get a knockout as well. Of course, if you land a left hook to the chin, you get to use the head as a lever, but there are no levers for the neck, so you will have to apply more force to your strike in order to get the same result. We can see this in action in muay Thai, MMA, and kickboxing matches, where a kick to the side of the neck can cause an opponent to lose consciousness immediately. Strikes directly to the back of the head (at the base of the skull) generate the same effect, but the minimum force required is lower, possibly because there is less muscle and other tissue between the axons and the point of impact. These strikes are illegal in most styles of fighting for sport, but they are still good to know, just in case you find yourself in a life-or-death scenario with an opportunity to strike there.

Use your brain to knock out your opponent. Now that we have a basic understanding of diffuse axonal injury, the obvious next question is, “How can I use this knowledge to become a better fighter?” Sometimes the right visualization of the process is all it takes so give your training a significant edge. When you throw a punch, think about how your punch will rotate your opponent’s head. If you give your opponent a linear palm strike to the face, you will probably do a lot of damage to your opponent, but if you can strike and then move your hand up and over, forcing your opponent to look up at the ceiling, you will probably have a better chance of knockout from that strike. Another way to adjust your training is to practice hitting something that can rotate. Some heavy bags or double-end bags can rotate when you hit them, or you can try out the Quest Training AllStrike, which functions much like a focus mitt in the shape of a human head for fine-tuning your targeting, but it also provides realistic rotational feedback. If you can start understanding when you are spinning a head versus when you are pushing it back, you are on your way to being a better knockout artist.

Let us assume that the persistence or repetition of a reverberatory activity (or "trace") tends to induce lasting cellular changes that add to its stability. ... When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased.

Axon Framework,

Terror is the widening of perspective and perception. The horror was in knowing I was swimming down to a place most of us leave when we get out of diapers and into training pants. I could see it on Ollie’s face, too. When rationality begins to break down, the circuits of the human brain can overload. Axons grow bright and feverish. Hallucinations turn real: the quicksilver puddle at the point where perspective makes parallel lines seem to intersect is really there; the dead walk and talk; a rose begins to sing.

American writer and biologist Frederick Kenyon (1867-1941) was the first to explore the inner workings of the bee brain. His 1896 study, in which he managed to dye and characterize numerous types of nerve cells of the bee brain, was, in the words of the world's foremost insect neuroanatomist, Nick Strausfeld, 'a supernova.' Not only did Kenyon draw the branching patterns of various neuron types in painstaking detail, but he also high­lighted, for the first time in any organism, that these fell into clearly identifi­able classes, which tended to be found only in certain areas of the brain. One such type he found in the mushroom bodies is the Kenyon cells, named in his honor. Their cell bodies -- the part of the neuron that con­tains the chromosomes and the DNA -- decoding machinery -- are in a peripheral area enclosed by the calyx of each mushroom body (the mush­room's 'head'), with a few additional ones on the sides of or underneath the calyces. A finely arbored dendritic tree (the branched struc­ture that is a nerve cell's signal 'receiver') extends into the mushroom body calyx, and a single axon (the neuron's 'information-sending output cable') extends from each cell into the mushroom body pedunculus (the mushroom's 'stalk'). Extrapolating from just a few of these characteristically shaped neu­rons that he could see, Kenyon suggested (correctly) that there must be tens of thousands of such similarly shaped cells, with parallel outputs into each mushroom body pedunculus. (In fact, there are about 170,000 Kenyon cells in each mushroom body.) He found neurons that connect the an­tennal lobes (the primary relays processing olfactory sensory input) with the mushroom body input region (the calyces, where the Kenyon cells have the fine dendritic trees) -- and even suggested, again correctly, that the mushroom bodies were centers of multisensory integration. Kenyon's 1896 brain wiring diagram [is a marvel]. It contains several classes of recognizable neuron types, with some suggestions for how they might be connected. Many neurons have extensions as widely branched as full­grown trees -- only, of course, much smaller. Consider that the drawing only shows around 20 of a honey bee brain's ~850,000 neurons. We now know that each neuron, through its many fine branches, can make up to 10,000 connection points (synapses) with other neurons. There may be a billion synapses in a honey bee's brain -- and, since the efficiency of synapses can be modified by experience, near-infinite possibility to alter the informa­tion flow through the brain by learning and memory. It is a mystery to me how, after the publication of such work as Kenyon's, anyone could have suggested that the insect brain is simple, or that the study of brain size could in any way be informative about the complexities of information pro­cessing inside a brain. Kenyon apparently suffered some of the anxieties all too familiar to many early-career researchers today. Despite his scientific accomplish­ments, he had trouble finding permanent employment, and moved be­tween institutions several times, facing continuous financial hardship. Eventually, he appears to have snapped, and in 1899 Kenyon was arrested for 'erratic and threatening behavior' toward colleagues, who subsequently accused him of insanity. Later that year, he was permanently confined to a lunatic asylum, apparently without any opportunity ever to rehabilitate himself, and he died there more than four decades later -- as Nick Strausfeld writes, 'unloved, forgotten, and alone.' It was not to be the last tragedy in the quest to understand the bee brain.

This heterogeneity [of vasopressin cells] is not by design but by accident. The patterns of gene expression in any neuron are not rigidly fixed by genetic nature, they arise from the unique experience of each cell in its life from birth to adulthood. The innervation of each cell is not predetermined with precision. Axons that reach the supraoptic nucleus may be guided there by developmental cues, but which particular cells each axon contacts is an opportunistic accident. There are mistakes; developmental cues are imperfect and some axons get lost or misled and make inappropriate connections. The brain has to be robust against such imperfection; the cost of doing everything perfectly is too high. Vasopressin cells are complex, but this does not make them clever, and the differences between cells certainly do mot make each cell uniquely clever. I am not interested in the idea that the brain does clever things because it hosts 100 billion clever machines. The wonder is that it does clever things with machines that are messy, noisy, and imperfect.