N Cortex Quotes

A neurosurgeon once told me about operating on the brain of a young man with epilepsy. As is customary in this kind of operation, the patient was wide awake, under only local anesthesia, while the surgeon delicately explored his exposed cortex, makingsure that the parts tentatively to be removed were not absolutely vital by stimulating them electrically and asking the patient what he experienced. Some stimulations provoked visual flashes or hand-raisings, others a sort of buzzing sensation, but one spot produced a delighted response from the patient: "It's 'Outta Get Me' by Guns N' Roses. my favorite heavy metal band!" I asked the neurosurgeon If he had asked the patient to sing or hum along with the music, since it would be fascinating to learn how "high fidelity" the provoked memory was, would it be in exactly the same key and tempo as the record? Such a song (unliken"Silent Night") has one canonical version. so we could simply have superimposed a recording of the patients humming with the standard record and compared the results. Unfortunately, even though a tape recorder had been running during the operation, thesurgeon hadn't asked the patient to sing along. ''Why not?" I asked, and he replied: "I hate rock music!' Later in the conversation the neurosurgeon happened to remark that he was going to have to operate again on the same young man. and I expressed the hope that he would just check to see if he could restimulate the rock music, and this time ask the fellow to sing along. "I can't do it." replied the neurosurgeon. "since I cut out that part." "It was part of the epileptic focus?" I asked. "No,'' the surgeon replied, ''I already told you — I hate rock music.

Diallo, a West African immigrant in New York, matched a description of a rapist. Four white officers questioned him, and when the unarmed Diallo started to pull out his wallet, they decided it was a gun and fired forty-one shots. The underlying neurobiology concerns “event-related potentials” (ERPs), which are stimulus-induced changes in electrical activity of the brain (as assessed by EEG—electroencephalography). Threatening faces produce a distinctive change (called the P200 component) in the ERP waveform in under two hundred milliseconds. Among white subjects, viewing someone black evokes a stronger P200 waveform than viewing someone white, regardless of whether the person is armed. Then, a few milliseconds later, a second, inhibitory waveform (the N200 component) appears, originating from the frontal cortex—“Let’s think a sec about what we’re seeing before we shoot.” Viewing a black individual evokes less of an N200 waveform than does seeing someone white. The greater the P200/N200 ratio (i.e., the greater the ratio of I’m-feeling-threatened to Hold-on-a-sec), the greater the likelihood of shooting an unarmed black individual.

Take, for example, the following sentence: “I prefer to eat with a fork and a camel.” Your brain has just generated an N400 wave, an error signal evoked by a word or an image which is incompatible with the preceding context.11 As its name suggests, this is a negative response that occurs at about four hundred milliseconds after the anomaly and arises from neuronal populations of the left temporal cortex that are sensitive to word meaning. On the other hand, Broca’s area in the inferior prefrontal cortex reacts to errors of syntax, when the brain predicts a certain category of word and receives another,12 as in the following sentence: “Don’t hesitate to take your whenever medication you feel sick.” This time, just after the unexpected word “whenever,” the areas of your brain that specialize in syntax emitted a negative wave immediately followed by a P600 wave—a positive peak that occurs around six hundred milliseconds. This response indicates that your brain detected a grammar error and is trying to repair it.

At the present, a plausible nominee for the neural substrate of consciousness is one of the most important neurological discoveries of our time. T h is is that tangle of tiny internuncial neurons called the reticular formation, which has long lain hidden and unsuspected in the brainstem. It extends f rom the top of the spinal cord through the brainstem on up into the thalamus and hypothalamus, attracting collaterals from sensory and motor nerves, almost like a system of wire-tabs on the communication lines that pass near it. But this is not all. It also has direct lines of command to half a dozen major areas of the cortex and probably all the nuclei of the brainstem, as we ll as sending fibers down the spinal cord where it influences the peripheral sensory and motor systems. Its function is to sensitize or “awaken” selected nervous circuits and desensitize others, such that those who pioneered in this work christened it “ t he waking b r a i n

The Emory researchers who identified the four phases of meditation found that when meditators slip out of the focused attention of the TPN and into Mind Wandering, the DMN activates. The wandering mind of the DMN has a “me” orientation, focusing on the self. It may flit from what’s going on at the moment (“Is that a mosquito buzzing?”) to future worries (“I’m nervous about next week’s exam”) to the past (“I’m so mad at my brother Jim for calling me a sissy at my fifth birthday party”). The precuneus contributes to both self-referential focus and episodic memory. Disturbing memories are played and replayed. The idle brain defaults to what is bothering us, both recent and long-past events. These egocentric musings of the wandering mind form the fabric of our sense of self. When you quiet your TPN in meditation, you open up a big empty space in consciousness. For a few moments, the brain is quiet, and you feel inner peace. Then the engine starts revving. The DMN kicks in, bringing with it a cascade of worries and random thoughts. You’re doing 2,000 RPM in Park, but going nowhere. And it gets worse. The DMN has a rich neural network connecting it with other brain regions. Through this, it busily starts recruiting other brain regions to go along with its whining self-absorption. It commandeers the brain’s CEO, the prefrontal cortex. This impairs executive functions like memory, attention, flexibility, inhibition, planning, and problem-solving. 2.5. Nerves from the Default Mode Network reach out to communicate with many other parts of the brain. The DMN also recruits the insula, a region that integrates information from other parts of the brain. It has special neurons triggered by emotions that we feel toward other people, such as resentment, embarrassment, lust, and contempt. We don’t just think negative thoughts; we feel them emotionally too. At this stage, the meditator isn’t just wallowing in a whirlwind of self-centered thoughts. The DMN has taken the brain’s CEO hostage, while through the insula it starts replaying all the slights, insults, and disappointments we’ve experienced in our relationships. The quiet meditative space we experienced just a few moments before has been destroyed. This drives meditators absolutely nuts. No sooner do they achieve nirvana, the still, quiet place of Bliss Brain, than the DMN serves up a smorgasbord of self-absorbed fantasies. It pulls us into negative emotional states—then drags the rest of the brain along behind it. The DMN. Hmm . . . that acronym reminds me of something: “the DeMoN.” The DMN is the demon that robs me of the inner peace I’m seeking through meditation

I knew what insomnia did. My thalamus—the central switching station of the brain—would burn out. All the functions of the prefrontal cortex—emotional regulation, planning ability, reality-testing—it would all go to shit. Then my brain would feed on its own neurons and synaptic connections while my emotions completely took over. Basically, I had to sleep, or I’d finish my descent into insanity pretty fast.

La vie apparut et se distribua à la conquête de la Terre. Le temps s'attaquait à l'espace. Ce fut la complication. Les êtres se ramifièrent, se spécialisèrent, d'éloignèrent les uns des autres, chacun assurant sa perpétuation par la dévoration des autres. L'Evolution inventa des formes raffinées de prédation, de reproduction et de déplacement. Traquer, piéger, tuer, se reproduire fut le motif général. [...] Le soleil avait déjà pris feu. Il fécondait la tuerie de ses propres photons et il mourrait en s'offrant. La vie était le nom donné au massacre en même temps que le requiem du soleil. Si un Dieu était vraiment à l'origine de ce carnaval, il aurait fallu un tribunal de plus haute instance pour le traduire en justice. Hier, l'homme apparut, champignon à foyer multiple. Son cortex lui donna une disposition inédite: porter au plus haut degré la capacité de détruire ce qui n'était pas lui-même tout en se lamentant d'en être capable. A la douleur s'ajoutait la lucidité. L'horreur parfaite.