READ --->> An endless and colorful world of hallucinations (PART I)
Alpha rhythm suppression and hallucinations
Alpha rhythm suppression is the most reliable correlate of the psychedelic state and can serve as a marker of the visual intensity of the psychedelic experience. However, the alpha rhythm also decreases in many other states - for example, when a person's eyes are open. However, a decrease in alpha rhythm power also occurs when the eyes are closed under psychedelics. In this regard, Lior Roseman suggests that alpha rhythm suppression may be related to the processing of images only psychedelic.
There is another view of alpha rhythm suppression - perhaps it alludes to a shift in information processing from external to internal and is the very factor that causes hallucinations. In a study conducted by M. Kometer and his colleagues measured alpha rhythm power before and during stimulus presentation. When instead of psychedelics the subjects were given a placebo, in the absence of a visual task, it was found: the excitability of the visual network decreases due to high levels of inhibition, which correlates with high power of the alpha rhythm in the parieto-occipital area. But the alpha rhythm power is attenuated by psilocybin at the prestimulus site, and also prevents the subsequent stimulus-induced decrease in power. It turns out that in the absence of the stimulus the visual cortex is excited, and in the presence of the stimulus it is inhibited. Similarly, computational models suggest that increased visual cortex excitability can destabilize spontaneous neuronal activity, leading to elementary visual hallucinations.
But the authors note that the correlation between alpha rhythm power attenuation and visual hallucination intensity did not reach statistical significance, so perhaps the alpha rhythm is not the main protagonist in generating hallucinations.
On the other hand, studies at the cellular level show a similar pattern of neuronal activation-inhibition in the presence and absence of a stimulus. Activation of the serotonin receptor 5-HT2A suppresses the activity of neurons with a high frequency of excitation. These neurons are usually activated by external visual stimuli. In contrast, neurons with low excitation frequency are activated by the 5-HT2A receptor. These neurons respond to stimulus-independent internal background activity.
In one of his works, Christopher Timmermann found a strong correlation between a decrease in alpha rhythm power with minute-to-minute changes in subjective intensity and the amount of DMT in plasma. The author suggests that the observed appearance of theta/delta rhythms in combination with the characteristic "collapse" of alpha/beta rhythms is due to "breakthrough experience," a perceptual mechanism by which the brain switches from processing exogenously received information to a state in which processing is controlled endogenously. Perhaps this rhythm inversion is precisely related to the processing switch: in the unaltered state of consciousness, alpha and beta rhythms dominate, while theta and delta appear in the relaxed, near-sleep state.
In another paper conducted by Leor Roseman in 2016, the authors investigated how much the functional connectivity of retinotopically organized regions of different areas of the primary visual cortex (V1 and V3) changes under LSD. The scientists hypothesized that connectivity would increase in the congruent areas of V1 and V3 responsible for responding to horizontal and vertical stimuli, i.e., for example, connectivity would be greater between the area of V1 responding to horizontal stimuli and V3 responding to the same stimuli. This turned out to be the case. This means that:
Alpha rhythm suppression is the most reliable correlate of the psychedelic state and can serve as a marker of the visual intensity of the psychedelic experience. However, the alpha rhythm also decreases in many other states - for example, when a person's eyes are open. However, a decrease in alpha rhythm power also occurs when the eyes are closed under psychedelics. In this regard, Lior Roseman suggests that alpha rhythm suppression may be related to the processing of images only psychedelic.
There is another view of alpha rhythm suppression - perhaps it alludes to a shift in information processing from external to internal and is the very factor that causes hallucinations. In a study conducted by M. Kometer and his colleagues measured alpha rhythm power before and during stimulus presentation. When instead of psychedelics the subjects were given a placebo, in the absence of a visual task, it was found: the excitability of the visual network decreases due to high levels of inhibition, which correlates with high power of the alpha rhythm in the parieto-occipital area. But the alpha rhythm power is attenuated by psilocybin at the prestimulus site, and also prevents the subsequent stimulus-induced decrease in power. It turns out that in the absence of the stimulus the visual cortex is excited, and in the presence of the stimulus it is inhibited. Similarly, computational models suggest that increased visual cortex excitability can destabilize spontaneous neuronal activity, leading to elementary visual hallucinations.
On the other hand, studies at the cellular level show a similar pattern of neuronal activation-inhibition in the presence and absence of a stimulus. Activation of the serotonin receptor 5-HT2A suppresses the activity of neurons with a high frequency of excitation. These neurons are usually activated by external visual stimuli. In contrast, neurons with low excitation frequency are activated by the 5-HT2A receptor. These neurons respond to stimulus-independent internal background activity.
In one of his works, Christopher Timmermann found a strong correlation between a decrease in alpha rhythm power with minute-to-minute changes in subjective intensity and the amount of DMT in plasma. The author suggests that the observed appearance of theta/delta rhythms in combination with the characteristic "collapse" of alpha/beta rhythms is due to "breakthrough experience," a perceptual mechanism by which the brain switches from processing exogenously received information to a state in which processing is controlled endogenously. Perhaps this rhythm inversion is precisely related to the processing switch: in the unaltered state of consciousness, alpha and beta rhythms dominate, while theta and delta appear in the relaxed, near-sleep state.
In another paper conducted by Leor Roseman in 2016, the authors investigated how much the functional connectivity of retinotopically organized regions of different areas of the primary visual cortex (V1 and V3) changes under LSD. The scientists hypothesized that connectivity would increase in the congruent areas of V1 and V3 responsible for responding to horizontal and vertical stimuli, i.e., for example, connectivity would be greater between the area of V1 responding to horizontal stimuli and V3 responding to the same stimuli. This turned out to be the case. This means that:
- The primary visual cortex is involved in visual images generated with the eyes closed.
- Strengthening of connectivity occurs according to the internal architecture of the cortex. It turns out that the visual cortex behaves as if it were receiving spatially localized visual information.
Thus, summing up a little, we do see that alpha rhythm suppression has been observed in many studies. There is still room for interpretation: some stick to the hypothesis of switching processing from external to internal, while others believe that it is still the same mechanism that works when processing images - no matter what, psychedelic or ordinary. The switching hypothesis seems reasonable: after all, the cortex continues to activate as if it sees something, and it turns out that the presence of a stimulus in the "consensual" reality is not so important - enough stimulus that it generates itself (for example, spontaneous arousal). I wonder what the adherents of "peripheral theories" would say, had they lived to see these times and noticed how much evidence there is now for the "central" hypothesis of hallucination generation...?
DMT-trips and curly cabbage
Imagine a curly cabbage. Do you see how curved its surface is compared to an ordinary cabbage? The point is that a curly cabbage is an example of a hyperbolic object. This is one example Andreas Emilson, a mathematician and director of the Qualia Research Institute, gives of hyperbolic space. He also suggested that at the peak of the DMT trip, space becomes hyperbolic.
Hyperbolic geometry challenges Euclid's fifth postulate about the parallelism of lines, has the sum of triangle angles less than 180 degrees and other properties of interest to mathematicians. For example, symmetry. In hyperbolic geometry an infinite number of its types is possible!
An imaginary ant, walking one centimeter at a time and making a 90-degree turn each time, repeating this exercise five times, will be able to find itself at the starting point-what is impossible in Euclidean geometry is made real in hyperbolic geometry. By the way, there are even studies claiming that our perception in an unchanged state of consciousness fits more within the framework of non-Euclidean geometry.
DMT-trips and curly cabbage
Imagine a curly cabbage. Do you see how curved its surface is compared to an ordinary cabbage? The point is that a curly cabbage is an example of a hyperbolic object. This is one example Andreas Emilson, a mathematician and director of the Qualia Research Institute, gives of hyperbolic space. He also suggested that at the peak of the DMT trip, space becomes hyperbolic.
Hyperbolic geometry challenges Euclid's fifth postulate about the parallelism of lines, has the sum of triangle angles less than 180 degrees and other properties of interest to mathematicians. For example, symmetry. In hyperbolic geometry an infinite number of its types is possible!
An imaginary ant, walking one centimeter at a time and making a 90-degree turn each time, repeating this exercise five times, will be able to find itself at the starting point-what is impossible in Euclidean geometry is made real in hyperbolic geometry. By the way, there are even studies claiming that our perception in an unchanged state of consciousness fits more within the framework of non-Euclidean geometry.
Andreas Emilson writes the following in his 2017 blog:
Andreas also divided the development of the DMT experience into several stages in which, depending on the dose, one goes from Euclidean symmetry to hyperbolic symmetry.
In this work, Andreas explained the mechanisms of psychedelic states through several basic processes: disruption of control, "drifting," facilitated pattern recognition, and symmetrical texture repetition.
In this work, Andreas explained the mechanisms of psychedelic states through several basic processes: disruption of control, "drifting," facilitated pattern recognition, and symmetrical texture repetition.
- Disruption of control. In the normal state, our perception is limited by top-down control, which means suppressing information that is not currently relevant and correcting afferent sensory information based on our own expectations. Most of the brain's feedback loops are inhibitory, which means that human consciousness is limited rather than free. In the retina, for example, there is lateral inhibition to enhance image contrast. Rapid inhibition in the cortex can also be applied both bottom-up and laterally - this is called the synaptic triad of rapid inhibition.
Also, according to the REBUS model, while taking psychedelics, top-down information processing becomes weaker, and sensory information, whose processing is controlled by ascending information in normal states, begins to play a greater role. This allows the ascending information to have a greater impact on our conscious experience.
- "Drifting." The texture, shape and general structure of objects and scenery gradually distort, melt and transform into each other.
- Easy pattern recognition. People in general tend to group independent objects into coherent figures: clouds as dogs, faces in trees, etc. However, under psychedelics this happens much more often.
- Symmetric Texture Repetition. Textures repeatedly reflecting on their own surface in a complex and symmetrical way.
Andreas explains this as follows. Under the influence of DMT, the rate of symmetry detection increases, inhibitory control decreases. The person quickly finds more relationships between objects, which creates a network of measured subjective distances that cannot be embedded in Euclidean three-dimensional space. There is also an overflow of symmetry. Everything on which attention is focused begins to branch out, copy itself, and multiply, saturating the scene to the point that it can no longer be perceived in Euclidean space.
Conclusion
Starting from a historical perspective, we have reached contemporary research and mechanisms of visual hallucination generation. Kluwer's "permanent forms" so hooked me in that for specific visual objects, explanatory mechanisms for their generation were proposed based on retinotopic cortical organization (projections from the retina to the visual cortex), and yet substantiated mathematically. When I moved on to more modern research, I felt a dissatisfaction that I could not understand. In the "Kluwer wave," I kept looking for that there would be studies explaining specific visual images. But modern research on visual hallucinations is described phenomenologically and goes to fMRI pictures with activation zones or evoked potential plots in general. It turned out that dissatisfaction is a reflection of that very distressing "explanatory gap" when pictures and graphs do not allow cognition of qualia.
According to philosopher Chalmers, qualia is what accompanies every experience, that very subjectivity of the individual, the question "why is my every action accompanied by a feeling?", and that chasm that separates the two people - one cannot look into someone else's qualia, but it is what makes the subjective experience unique.
Overall results:
1. The psychedelic experience has some structure and can be similar from person to person;
2. Visual hallucinations may be due to a switch from processing external information to internal information - alpha rhythm suppression, increased beta/theta rhythms are often observed in visual hallucination studies and may be involved in this process;
3. Visual hallucinations may be due to suppression of top-down control and increased weight of bottom-up information processing, which interferes with "making predictions" about how "consensual" reality works and generating a completely nonconsensual reality;
4. Perception of space under psychedelics, and especially under DMT can become hyperbolic.
READ --->> An endless and colorful world of hallucinations (PART I)
Starting from a historical perspective, we have reached contemporary research and mechanisms of visual hallucination generation. Kluwer's "permanent forms" so hooked me in that for specific visual objects, explanatory mechanisms for their generation were proposed based on retinotopic cortical organization (projections from the retina to the visual cortex), and yet substantiated mathematically. When I moved on to more modern research, I felt a dissatisfaction that I could not understand. In the "Kluwer wave," I kept looking for that there would be studies explaining specific visual images. But modern research on visual hallucinations is described phenomenologically and goes to fMRI pictures with activation zones or evoked potential plots in general. It turned out that dissatisfaction is a reflection of that very distressing "explanatory gap" when pictures and graphs do not allow cognition of qualia.
According to philosopher Chalmers, qualia is what accompanies every experience, that very subjectivity of the individual, the question "why is my every action accompanied by a feeling?", and that chasm that separates the two people - one cannot look into someone else's qualia, but it is what makes the subjective experience unique.
Overall results:
1. The psychedelic experience has some structure and can be similar from person to person;
2. Visual hallucinations may be due to a switch from processing external information to internal information - alpha rhythm suppression, increased beta/theta rhythms are often observed in visual hallucination studies and may be involved in this process;
3. Visual hallucinations may be due to suppression of top-down control and increased weight of bottom-up information processing, which interferes with "making predictions" about how "consensual" reality works and generating a completely nonconsensual reality;
4. Perception of space under psychedelics, and especially under DMT can become hyperbolic.
READ --->> An endless and colorful world of hallucinations (PART I)