Some new entoptic phenomena

doi:10.1016/0042-6989(78)90255-9

Vision Research

Volume 18, Issue 12, 1978, Pages 1633-1639

https://doi.org/10.1016/0042-6989(78)90255-9 Get rights and content

Abstract

Several entoptic phenomena are described, arising in a range of conditions from free-viewing with closed lids to deep pressure on the eyeballs. The resulting phosphenes provide some clues and some puzzles concerning the organisation of the visual system, from the retina to the cortex.

References (12)

CollinsC.C. et al.
Muscle tension during unrestrained human eye movements
J. Physiol.
(1975)
FriedmanB.
Observations on entoptic phenomena
Archs Ophthal.
(1942)
HelmholtzH. von
HubelD.H. et al.
Receptive fields of single neurons in the cat's striate cortex
J. Physiol.
(1959)
HubelD.H. et al.
Receptive fields and functional architecture of the monkey striate cortex
J. Physiol.
(1968)
MaxwellJ.C.
On the unequal sensibility of the Foramen Centrale to light of different colours
Rep. Br. Assoc.
(1856)

There are more references available in the full text version of this article.

Cited by (57)

A mathematical model of embodied consciousness
2017, Journal of Theoretical Biology
Citation Excerpt :
Various spiritual practices (e.g., meditation), the use of hallucinogenic drugs (e.g., mescaline), extreme life experiences (e.g., near death experiences), dreams, phenomena of entoptic vision induced by ocular pressure, and clinical conditions have been associated with reported subjective experiences of strange and fascinating spatial patterns in consciousness: radial patterns, spirals, funnels, cobwebs, honeycomb lattices and triangles, deep tunnels, which have then been a topic of artistic representation in many cultures (e.g., mandalas) (Klüver, 1926, 1966; Tyler, 1978; Fregnac, 2003; Siegel, 2005). Such patterns have been hypothesized to reflect the inner structure of spatial consciousness as a level of representation and a mode of access to information (Tyler, 1978, as cited in Fregnac, 2003). We can wonder whether our model can predict similar patterns, as would be expected from a valid model of consciousness, given their importance in human experience.
We introduce a mathematical model of embodied consciousness, the Projective Consciousness Model (PCM), which is based on the hypothesis that the spatial field of consciousness (FoC) is structured by a projective geometry and under the control of a process of active inference. The FoC in the PCM combines multisensory evidence with prior beliefs in memory and frames them by selecting points of view and perspectives according to preferences. The choice of projective frames governs how expectations are transformed by consciousness. Violations of expectation are encoded as free energy. Free energy minimization drives perspective taking, and controls the switch between perception, imagination and action. In the PCM, consciousness functions as an algorithm for the maximization of resilience, using projective perspective taking and imagination in order to escape local minima of free energy. The PCM can account for a variety of psychological phenomena: the characteristic spatial phenomenology of subjective experience, the distinctions and integral relationships between perception, imagination and action, the role of affective processes in intentionality, but also perceptual phenomena such as the dynamics of bistable figures and body swap illusions in virtual reality. It relates phenomenology to function, showing the computational advantages of consciousness. It suggests that changes of brain states from unconscious to conscious reflect the action of projective transformations and suggests specific neurophenomenological hypotheses about the brain, guidelines for designing artificial systems, and formal principles for psychology.
The visual snow phenomenon
2014, Journal Francais d'Ophtalmologie
La neige visuelle (visual snow) est un symptôme décrit par certains patients et souvent mal connu des ophtalmologistes. Il s’agit de la perception permanente d’une vision granitée ou neigeuse, parfois associée à des palinopsies, à une perception exagérée du phénomène entoptique du champ bleu et à une photophobie. Nous rapportons une série de patients souffrant du phénomène de neige visuelle, afin d’en préciser les caractéristiques et d’en discuter la physiopathologie.
Étude prospective des patients ayant été diagnostiqués entre septembre 2010 et décembre 2012 avec un phénomène de « neige visuelle ». Chez chacun d’entre eux ont été réalisés un interrogatoire formalisé, un test à la grille d’Amsler, un champ visuel automatisé des 20° centraux, un test 15 Hue désaturé de la vision des couleurs, un électrorétinogramme global, multifocal et pattern et des potentiels évoqués visuels flash et damiers (Métrovision^©). La réalisation d’une imagerie cérébrale n’était pas systématique.
Douze patients âgés de 9 à 48 ans ont été inclus (six hommes et six femmes, 85 % d’étudiants) Les signes associés au phénomène de neige visuelle étaient variables : palinopsies (50 %), phénomène entoptique du champ bleu permanent (40 %), photophobie (30 %), migraines (30 %) ; dans 20 % des cas existait la notion d’une prise de toxiques associée au début des symptômes.
Cette étude met en évidence le caractère typique et reproductible des symptômes décrits par les patients rapportant un phénomène de neige visuelle, ce qui lui confère une forte présomption de substratum organique. La physiopathologie du phénomène demeure incertaine ; l’hypothèse d’un abaissement du seuil de perception des images entoptiques ne permet d’expliquer que partiellement les symptômes rapportés.
Visual snow is a symptom described by some patients and poorly recognized by ophthalmologists. It consists in the permanent perception of a textured or a snowy vision, sometimes associated with palinopsia, exaggerated perception of the blue field entoptic phenomenon and photophobia. We report a group of patients suffering from visual snow in order to precise its characteristics and discuss its pathophysiology.
Prospective study of patients diagnosed between September 2010 and December 2012 with a visual snow phenomenon. For each patient, a formal ophthalmologic examination, an Amsler grid test, an automated visual field (central 20°), a color vision test (15 Hue), a full field, a pattern and a multifocal electroretinogram as well as flash and pattern visual evoked potentials (Métrovision^©) were performed. A brain imaging was not systematically performed.
Twelve patients aged 9–48 old were included (six men and six women, 85 % of students). Several signs were variably associated with the visual snow phenomenon: palinopsia (50 %), constant blue field entoptic phenomenon (40 %), photophobia (30 %), migraine (30 %); in 20 % of cases, an initial toxic intake was found (20 %).
This study highlights the reproducibility of typical symptoms described by patients reporting the visual snow phenomenon. This feature strongly supports the organic origin of the phenomenon. The pathophysiology of this phenomenon, however, remains unclear; the hypothesis of a lower threshold for perception of entoptic images cannot entirely account for the reported symptoms.
Spatiotemporally varying visual hallucinations: II. Spectral classification and comparison with theory
2014, Journal of Theoretical Biology
Citation Excerpt :
Although the retinal cause of the hallucination seemingly implies that the patterns of neural activity corresponding to hallucinations occur at the retina, but degenerative retinal disease is hypothesized to induce neuronal hyperexcitability in the visual cortex as neurons starved of input adaptively increase their gains until activity reaches high levels (Madill and Ffytche, 2005; Tan and Sabel, 2006; Ffytche, 2008). The patterns seen after self-induced retinal deformation are binocular so they must occur at a point where binocular processing takes place (Tyler, 1978), the first (but not only) such area being the primary visual cortex. Acute zonal occult outer retinopathy (AZOOR) is a rare condition that involves localized loss of vision accompanied by photopsia (Carrasco et al., 2005; Gass et al., 2002; Holz and Spaide, 2005).
In order to better understand the nature of visual hallucinations, and to test predictions of spatiotemporally oscillating hallucinations from a recent corticothalamic model of visual dynamics, clinical descriptions of hallucinations are used to establish boundaries on the spatiotemporal frequencies observed in various disorders. Detailed comparisons with hallucinations during migraine aura demonstrate that key features are consistent with corticothalamic origin and specific abnormalities, but underline the need for more detailed quantitative data to be obtained on temporally oscillating hallucinations more generally.
The shapes of things that were: applying Huarpa art (AD 250-700) to the Lewis-Williams and Dowson entoptic model for shamanism
2023, Boletin del Museo Chileno de Arte Precolombino
Modelling phenomenological differences in aetiologically distinct visual hallucinations using deep neural networks
2023, Frontiers in Human Neuroscience
A Dictionary of Hallucinations
2023, A Dictionary of Hallucinations

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: Supported by the Smith-Kettlewell Eye Research Foundation and NIH grants EY 01186.

View full text

Some new entoptic phenomena

Abstract

Muscle tension during unrestrained human eye movements

J. Physiol.

Observations on entoptic phenomena

Archs Ophthal.

Receptive fields of single neurons in the cat's striate cortex

J. Physiol.

Receptive fields and functional architecture of the monkey striate cortex

J. Physiol.

On the unequal sensibility of the Foramen Centrale to light of different colours

Rep. Br. Assoc.