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LSD profoundly alters cognitive unity. Many people feel that the separation between the self and world dissolves when on LSD, and they begin to feel at one with everything. Conscious experience as a unified whole also breaks down on LSD, especially during the acute phase at high doses, so that perceptions that originate from inside are difficult to disentangle from those originating from outside. Experience itself becomes like movie frames slowed down so that each frame is perceivable. We know now that there are neurobiological reasons for this; hallucinogens have profound effects on global brain activity. Psilocybin, for example, decreases the connections between visual and sensorimotor networks, while it seems to increase the connectivity between the resting-state networks. Temporal integration is related to one’s sense of the current moment. Conscious experience is somehow located in time. We feel like we occupy an omnipresent widthless temporal point—the now. As Riccardo Manzotti says: Every conscious process is instantiated by patterns of neural activity extended in time. This apparently innocuous hypothesis hides a possible problem. If neural activity spans in time (as it has to do since neural activity consists in trains of temporally distributed spikes), something that takes place in different instants of time has to belong to the same cognitive or conscious process. For instance, what glues together the first and the last spike of neural activity underpinning the perception of a face? We know that neuronal oscillations at different frequencies act as this temporal glue. However, when you’re on LSD, this glue seems to dissolve. As Albert Hofmann and many others report, your normal sense of time vanishes on psychedelics. The famous bicycle trip on acid during which Hofmann reported that he felt he was not moving, and yet he arrived at home somehow, illustrates this distortion of the brain mechanisms that support our normal perception of the flow of time.
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