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The Corticocortical Feedback Loop
Moving onward from the visual cortex to higher processing centers along the visual pathway, Layer V pyramidal neurons are once again responsible for mediating corticocortical circuits along both dorsal and ventral streams, all the way up to the multi-modal sensory convergence areas in the pre-frontal cortex (PFC). Destabilization along this all-important binding pathway would allow for a multi-layered cascade of top-down excitatory feedback loops with extreme perceptual results. This is where 5-HT2A selective agonists stop being strictly perceptual and begin to affect the entirety of consciousness. Cross-lobe reciprocal pathways are essential for mediating our real-time multi-modal awareness of reality and the self. When these pathways become excited and begin to destabilize the perceptual effect goes beyond visual hallucination and becomes profoundly disorienting. A subject with heightened excitation along these pathways would experience very complex and disturbing changes in reality, such as visual frame-skipping; memory loss; memory gaps; temporal distortion; time lags; obsessive thought loops; logic traps; the inability to match words to objects; the inability to maintain a train of thought over a few seconds long before it repeats itself; the simultaneous “filling up” or overload of all senses; and the overwhelming urge to shut-down, hide, or recede from reality.
In contrast, once these cortical feedback circuits are fully interrupted and decoupled the subject loses all sense of self, time, and place; becomes profoundly quiet and peaceful inside; becomes infinitely large; floats through an idealized spirit world; and finds existential oneness with the universe. This state is often referred to in psycho-mystical terms as ego-death, the no-mind state, or transcendence. While in this state the subject is perfectly fine and appears to be meditating or in a light trance. The subjective experience of this state is similar in many ways to classic descriptions of out-of-body (OBEs) or near-death experiences (NDEs).
The subjective hallucinogenic and mystical effects of cortical decoupling are best demonstrated in emergent ketamine-induced states, where the visual cortex decouples from external reality and a boundless, formless dream-space appears to open. The mystical effects of cortical decoupling are described in similar terms by stroke victims, epileptics, meditation gurus, drug users, and people who use other technology such as transcranial-magnetic stimulation (TMS) to interrupt phase-coupled cross-lobe activity. At high doses 5-HT2A agonists can create similar decoupling results, yet not as quickly or drastically as the anesthetic ketamine. With orally-ingested psychedelics the journey through excitation to network destabilization to feedback overload to complete decoupling is a long and arduous journey taking many hours to reach full effect. In contrast, smoked or IV DMT administration can compress this process into about five minutes, with another ten or so minutes for the drug to metabolize and the process to entirely reverse itself. This rapid shifting through multi-phase brain states in such a short period of time is perhaps why DMT is considered so dramatic.
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