Psychedelic Information Theory : Chapter 09
Entoptic hallucination, geometric hallucinations, or phosphenes, are one of the most commonly reported visual effects of psychedelics. Phosphenes are a sensation of light caused by excitation of the retina by mechanical or electrical means. Pressure phosphenes can be created by applying pressure to the eyeballs through closed eyelids; flicker phosphenes are created in response to stroboscopic pulses of light; kinetic phosphenes are created in response to physical impact to the head, sometimes referred to as "seeing stars". (Fig. 1) Entoptic hallucinations are differentiated from eidetic (photographic) hallucinations in that they originate within the neural connections between the eye and cortex, as opposed to emerging within the cortex or midbrain. There is evidence that entoptic phosphene patterns have influenced human cultural and religious archetypes since 10,000 BCE.1,2,17
Entoptic hallucinations fall into predictable geometric patterns and can be measured by formal properties such as form constant, flicker rate, rotation, drift, and decay. Common phosphene forms include web, grid, checkerboard, clover-leaf, spiral, funnel, or more amorphous floating blobs and stars.3 Phosphene patterns may match recurring patterns in the natural world, such as cells, stars, sand dunes, flowers, clouds, and snakeskin (Fig. 2). Evidence suggests that the form constants of phosphenes are directly related to spatial relationships between the ring-like structure of the retinal cells and the grid-like or columnar neural structures of the visual cortex. (Fig. 3) The spontaneous production of geometric hallucinations is due to excitation and loss of stability in these retinal-cortical signal coupling pathways. The transition from seamless visual aliasing to spontaneous geometric patterns can be described as a transcritical or pitchfork bifurcation leading to an excited visual field reflecting the spatial organization of the recurrent network.4,5,6
Pulses in the same frequency range as brain waves (theta to gamma) are most effective in producing flicker phosphenes.3 Flicker phosphenes created by stroboscopic lights or mind-machines tend to be more amorphous at low frequencies(1-4hz), tend to fall into web, spiral, or cloverleaf patterns at medium frequencies (4-9hz), and tend to lock into grid or checkerboard patterns at higher frequencies (9-16hz+). Flicker phosphenes will have slow lateral drift at lower frequencies; a rotational drift at medium frequencies; and will maintain stability or produce fast lateral drift at higher frequencies.7 Presumably any technology which uses pulsating frequencies to produce phosphenes, such as transcranial magnetic stimulation (TMS), must also use pulses corresponding to this frequency range to produce substantial perceptual results.8
Flicker Phosphenes and Hallucinogenic Interrupt
Taking what we know about the production of geometric hallucinations in response to pulse activity within specific frequency ranges, it is possible to extrapolate that the multisensory interrupt of any hallucinogen must necessarily fall into the same range of @5-40hz, which is the general frequency range of human consciousness. According to the Control Interrupt Model of psychedelic action, any drug which produces a multisensory interrupt within the frequency band of waking consciousness will also necessarily produce flicker phosphenes and be considered hallucinogenic. If the multisensory interrupt is too slow or too fast the drug may still be considered psychedelic, empathogenic, entactogenic, or dissociative, but will be less likely produce significantly realized geometric flicker hallucinations. This same principle can be applied to audio and tactile sensory binding; any periodic sensory interrupt within the frequency band of human consciousness will necessarily induce field-like hallucinations with stable form constants and properties related directly to the interrupt frequency.
The evolution of flicker phosphenes can be described formally by the iterative properties of fractals or cellular automata, which over time turn simple repeating algorithms into complex patterns. (Fig. 4)20 Under the influence of psychedelics flicker phosphenes grow in intensity, become more elaborate, and become more structurally resolved over time.3 It can be assumed that this is because the modulatory interrupt of a hallucinogen is being applied directly to the sensory binding pathways via pharmacological interaction as opposed to being applied to the retinal or cortical networks via external electrical pulse stimulation. Because the modulatory interrupt of psychedelics is pharmacological, it is more difficult for the subject to fend off or ignore the periodic interrupt to retain multisensory stability; the very pathways that maintain stability are the pathways which are being interrupted. In a very physical way, the modulatory interrupt of the hallucinogen is literally hacking into or hijacking the sensory signaling pathways and overriding them with its own modulatory frequency. Because of this, the influence of the hallucinogenic flicker interrupt becomes explicit in sensory rendering; the subject may literally see or feel the geometric field interference as a fully embedded aspect of their perceptual reality.
Flicker phosphenes are the product of neurochemical saturation and have a substantial signal decay. There is evidence that electrically stimulated phosphenes take as long as 10-15 seconds to fully fade once the periodic stimulus is removed.9 Overlapping stereoscopic phosphenes will naturally create decaying interference patterns approaching fractal complexity. (Fig. 5) It can be assumed there is a saturation of signaling molecules that builds up at the site of synaptic interruption that persists for some period of time following each interrupt. The pulse of each interrupt can be described in terms of saturation attack and sustain; the fade of each interrupt can be described in terms of saturation decay and release (or ADSR envelope).10 Full saturation would mean a complete white-out of sensory information at the interrupt site; zero saturation would mean the interrupt site is cleared of signaling molecules and is presenting a darkened resting state. Saturation at the interrupt site increases and decreases in intensity over the period of each interrupt; this change in chemical saturation over the duration of each interrupt is subjectively perceived as a flicker or pulse of light intensity.
Because a hallucinogen my interrupt consciousness at many cycles per second, and because each pulse can have a saturation decay of up to 15 seconds, phosphenes will naturally drift laterally or radially across the visual field and create overlapping webs of many arising and decaying geometric patterns all visible within a single perceptual frame. This creates the formation of complex standing interference patterns. (Fig. 6) The web-like interference of multiple arising and decaying geometric grids creates a 3D meshwork that allows complex eidetic shapes to materialize spontaneously within the quickly morphing wire-frame. Visual saturation is most intense at the interstices of the wire-frame webs, creating the perception of bright dots or scintillating jewels where patterned lines overlap and intersect into nodes. These saturated pixel groups may correspond to actual hot-spots of neural activity in the columns of the visual cortex. These hot-spots are produced spontaneously in the wake of stimulus, creating a flood of glutamate wherever shafts of apical dendrites intersect with lateral projections from proximal neural columns.18 Glutamate flooding at lateral dendritic arbors of pyramidal neurons is the result of asynchronous glutamate release in the wake of 5-HT2A receptor agonism.19
It is widely assumed that geometric hallucinations and flicker phosphenes originate between the optic tract and visual cortex, but some subjective reports of psychedelic experimentation also describe a fast pulsation or rhythmic jitter felt in the muscles around the eyes. This sensation is most acute in the outside corner of the visual periphery, specifically along the lateral rectus and the junction where the inferior oblique passes over the inferior rectus (Fig. 7). This optical pulse may be difficult to discern in early parts of a psychedelic session, but becomes more acute and easier to sense as the session wears on. This rapid pulsation may be related to modulatory interrupt and saturation at the cortical columns that control optic muscles, generating a chain reaction in neural transduction felt as a muscle twitch or throb. Increasing or decreasing optic pressure naturally produces phosphenes; periodically interrupting the eye’s finely timed saccades with a muscle twitch may have a similar effect. In his experiments with phosphenes in the mid 1800s, Johannes Purkinje applied an aqueous extract of belladonna (scopolamine, atropine) directly to his eye to produce phosphenes. Because the effect was localized, Purkinje proposed that phosphenes may be related to cycloplegia, or partial paralysis of the eye muscles.21 Given these reports, it is reasonable to assume that any interruption of fine visual motor control, interruption of optic signal transduction, or change in optic pressure will necessarily produce phosphenes.
Entoptic vs. Eidetic Hallucination
Geometric hallucinations, or phosphenes, are considered to be entoptic, meaning they are a product of excitation and destabilization in spatial coupling between neural assemblies in the retina and visual cortex, and produce complex patterns similar to fractal recursion (Fig. 8). Entoptic hallucinations can be contrasted with eidetic hallucinations, which are more fully formed images that appear from visual memory or imagination. Psychedelic eidetic hallucinations are generally more explicitly personal than the abstract geometric forms associated with flicker phosphenes. Over the course of a psychedelic session hallucinations will start with flicker phosphenes and then increase in complexity from entoptic to eidetic content, often containing a seamless mixture of the two. It can be assumed that eidetic hallucinations only begin once serotonergic modulation of the forebrain has been sufficiently interrupted to allow cholinergic modulation of mid-brain vizualization.11 This transition from entoptic to eidetic hallucination is also associated with a transition from the high frequency beta or gamma state to a low frequency alpha or theta state.
Meditation and autohypnotic exercises are targeted to produce states of hypnogogia associated with theta waves and entoptic hallucination (Fig. 9). Drugs which naturally drive theta waves in the brain are called hypnotics. Some psychedelics are naturally hypnotic, others are hypnotic only in sensory deprivation or under the influence of a theta-band periodic driver.12 The hallucinogenic tea ayahuasca is a mixture of a high-frequency interrupt psychedelic (DMT) and a low-frequency hypnotic diver (the beta-carbolines harmine and harmaline). This synergistic blend of high-beta interrupt and slow-theta attenuators means that ayahuasca should promote both fast beta geometric flicker phosphenes as well as slow eidetic theta dream snippets. This prediction can resolve paradoxical EEG analysis of subjects under the influence of ayahuasca, which sometimes indicates increased power in high frequency beta and gamma coherence,13,14 but in the context of shamanic ritual shows increased power in slow-wave theta activity.15
Eidetic hallucination is considered to be rendered photographically or presented as a 3D virtual model. In psychedelic intoxication a strange conversion of eidetic and entoptic phenomena can occur when an eidetic image or symbol reproduces into a marching grid or kaleidoscopic network of repeating symbols with a juxtaposed eidetic image emerging within the repeating superstructure. For example, a subject may hallucinate a geometric grid of quickly spinning colored triangles, and as those triangles flicker across the visual field they suddenly cohere into a 3D wire-frame mesh of a more fully-realized eidetic snapshot of a human body or face. In addition to triangles, the overlaying grid may be composed of dots, circles, honeycomb, spiders, insects, centipedes, worms, snakes, reptiles, lizards, question marks, swastikas, teeth, piano keys, skulls, flowers, leaves, stars, eyes, billiard balls, dice, playing cards, human faces, alien faces, dancing elves, skeletons, clowns, jesters, writhing bodies, branching trees, cells, bacteria, paisleys, DNA, Japanese kanji, Byzantine tile patterns, Mesoamerican brick patterns, Native American totem patterns, Polynesian tiki patterns, and similar repeating archetypal forms.16 The fast flicker rate and embedded kaleidoscopic nature of this type of compound hallucination often defies formal description or the ability to accurately capture in art or memory. The hallucinogenic perception of a complex embedded symbolic grid or kinetic fractal superstructure is wholly unique to the tryptamine psychedelic experience; it may be the visual essence of what makes an experience authentically psychedelic.
 Williams JD, Dowson TA, et al. , 'The Signs of All Times: Entoptic Phenomena in Upper Palaeolithic Art'. Current Anthropology, Vol. 29, No. 2 (Apr., 1988), pp. 201-245
 Pettifor, Eric, 'Altered States: The Origin of Art in Entoptic Phenomena'. Internet Reference, 1996.
 Knoll M, Kuglerb J, et al., 'Effects of Chemical Stimulation of Electrically-Induced Phosphenes on their Bandwidth, Shape, Number and Intensity'. Sterotactic and Functional Neurosurgery, Vol. 23, No. 3, 1963
 Bressloff, Cowan, Golubitsky, Thomas, Wiener, 'What Geometric Visual Hallucinations Tell Us about the Visual Cortex'. Neural Computation 14 (2002) 473–491.
 Gutkin, Pinto, Ermentrout, 'Mathematical Neuroscience: From Neurons to Circuits to Systems'. Journal of Physiology - Paris 97 (2003) 209–219.
 Ermentrout, Cowen, 'A mathematical theory of visual hallucination patterns'. Biological Cybernetics 34-3 (1979) 137-150.
 Observations on the correlation between Hz and the form constants and properties of flicker phosphenes are generalized and based on subjective reports.
 Bokkon I, Kirby M, D’Angiulli A, 'TMS, phosphenes and visual mental imagery: A mini-review and a theoretical framework'. Symposium on Transcranial Magnetic Stimulation and Neuroimaging in Cognition and Behaviour Conference, Montreal, Quebec, Canada, 25 September 2008.
 Dobelle WH, Mladejovsky HG, 'Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind'. J Physiol. 1974 December; 243(2): 553–576.1.
 See "Control Interrupt Model of Psychedelic Action"
 Hobson, J. Allan, 'The Dream Drugstore: Chemically Altered States of Consciousness'. MIT Press, 2001.
 Subjective reports show that some tryptamines, such a the psilocybin and psilocin found in magic mushrooms, naturally make you feel sleepy and dreamy even in loud sensory environments. Other tryptamines, like LSD, can have paradoxically trance-like or stimulant-like qualities depending on the environmental drivers of set and setting.
 Riba J, Anderer P, et al., 'Topographic pharmaco-EEG mapping of the effects of the South American psychoactive beverage ayahuasca in healthy volunteers'. Br J Clin Pharmacol. 2002 June; 53(6): 613–628. doi: 10.1046/j.1365-2125.2002.01609.x.
 Stuckey DE, Lawson R, Luna LE, 'EEG gamma coherence and other correlates of subjective reports during ayahuasca experiences'. J Psychoactive Drugs. 2005 Jun;37(2):163-78.
 Hoffmann, E, 'Effects of a Psychedelic, Tropical Tea, Ayahuasca, on the Electroencephalographic (EEG) Activity of the Human Brain during a Shamanistic Ritual'. MAPS Spring (2001) 25-30.
 Accounts of geometric meshwork or marching rows of repeating archetypal forms are taken from subjective reports of psychedelic intoxication.
 Nicholson PT, Firnhaber RP, 'Autohypnotic Induction of Sleep Rhythms Generates Visions of Light with Form-constant Patterns'. Independent White Paper
 Nichols DE, 'Hallucinogens'. Pharmacology & Therapeutics Volume 101, Issue 2, February 2004, Pages 131-181
 Aghajanian GK, Marek GJ, 'Serotonin Induces Excitatory Postsynaptic Potentials in Apical Dendrites of Neocortical Pyramidal Cells '. Neuropharmacology Volume 36, Issues 4-5, 5 April 1997, Pages 589-599
 Levitated.net, 'Artifacts of Computation'. Internet Reference
 Melechi A, 'Seeing Stars: The Shifting Geometry of Phosphenes'. Trip Magazine, issue 10, 26-27, 2004.
Citation: Kent, James L. Psychedelic Information Theory: Shamanism in the Age of Reason, Chapter 09, 'Entoptic Hallucination'. PIT Press, Seattle, 2010.
Copyright: © James L. Kent, 2010. Some Rights Reserved. Please read copyright information before reproducing.