Phosphene

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An artist's representation of how some people may see phosphenes by retinal stimulation. Phosphene artistic depiction.gif
An artist's representation of how some people may see phosphenes by retinal stimulation.

A phosphene is the phenomenon of seeing light without light entering the eye. The word phosphene comes from the Greek words phos (light) and phainein (to show). Phosphenes that are induced by movement or sound may be associated with optic neuritis. [1] [2]

Contents

Phosphenes can be induced by mechanical, electrical, or magnetic stimulation of the retina or visual cortex, or by random firing of cells in the visual system. Phosphenes have also been reported by meditators [3] (called nimitta ), people who endure long periods without visual stimulation (the prisoner's cinema), or those who ingest psychedelic drugs. [4]

Causes

Mechanical stimulation

The most common phosphenes are pressure phosphenes, caused by rubbing or applying pressure on or near the closed eyes. They have been known since antiquity, and described by the Greeks. [5] The pressure mechanically stimulates the cells of the retina. Experiences include a darkening of the visual field that moves against the rubbing, a diffuse colored patch that also moves against the rubbing, well defined shapes such as bright circles that exist near or opposite to where pressure is being applied, [6] a scintillating and ever-changing and deforming light grid with occasional dark spots (like a crumpling fly-spotted flyscreen), and a sparse field of intense blue points of light. Pressure phosphenes can persist briefly after the rubbing stops and the eyes are opened, allowing the phosphenes to be seen on the visual scene. Hermann von Helmholtz and others have published drawings of their pressure phosphenes. One example of a pressure phosphene is demonstrated by gently pressing the side of one's eye and observing a colored ring of light on the opposite side, as detailed by Isaac Newton. [7] [8] [9]

Another common phosphene is "seeing stars" from a sneeze, laughter, a heavy and deep cough, blowing of the nose, a blow on the head or low blood pressure (such as on standing up too quickly or prior to fainting). It is possible these involve some mechanical stimulation of the retina, but they may also involve mechanical and metabolic (such as from low oxygenation or lack of glucose) stimulation of neurons of the visual cortex or of other parts of the visual system.[ citation needed ]

Less commonly, phosphenes can also be caused by some diseases of the retina and nerves, such as multiple sclerosis. The British National Formulary lists phosphenes as an occasional side effect of at least one anti-anginal medication.

The name "phosphene" was coined by J. B. H. Savigny, better known as the ship's surgeon of the wrecked French frigate Méduse . [10] It was first employed by Serre d'Uzes to test retinal function prior to cataract surgery. [11]

Electrical stimulation

Phosphenes have been created by electrical stimulation of the brain, reported by neurologist Otfrid Foerster as early as 1929. Brindley and Lewin (1968) inserted a matrix of stimulating electrodes directly into the visual cortex of a 52-year-old blind female, using small pulses of electricity to create phosphenes. These phosphenes were points, spots, and bars of colorless or colored light. [12] Brindley and Rushton (1974) used the phosphenes to create a visual prosthesis, in this case by using the phosphenes to depict Braille spots.

In recent years, researchers have successfully developed experimental brain–computer interfaces or neuroprostheses that stimulate phosphenes to restore vision to people blinded through accidents. Notable successes include the human experiments by William H. Dobelle [13] and Mark Humayun and animal research by Dick Normann.

A noninvasive technique that uses electrodes on the scalp, transcranial magnetic stimulation, has also been shown to produce phosphenes. [14]

Experiments with humans have shown that when the visual cortex is stimulated above the calcarine fissure, phosphenes are produced in the lower part of the visual field, and vice versa. [15]

Others

Phosphenes have been produced by intense, changing magnetic fields, such as with transcranial magnetic stimulation (TMS). These fields can be positioned on different parts of the head to stimulate cells in different parts of the visual system. They also can be induced by alternating currents that entrain neural oscillation as with transcranial alternating current stimulation. [16] In this case they appear in the peripheral visual field. [16] This claim has been disputed. The alternative hypothesis is that current spread from the occipital electrode evokes phosphenes in the retina. [17] [18] [19] Phosphenes created by magnetic fields are known as magnetophosphenes.

Astronauts exposed to radiation in space have reported seeing phosphenes. [20] Patients undergoing radiotherapy have reported seeing blue flashes of light during treatment; the underlying phenomenon has been shown to resemble Cherenkov radiation. [21]

Phosphenes can be caused by some medications, such as Ivabradine. [22]

Mechanism

Most vision researchers believe that phosphenes result from the normal activity of the visual system after stimulation of one of its parts from some stimulus other than light. For example, Grüsser et al. showed that pressure on the eye results in activation of retinal ganglion cells in a similar way to activation by light. [23] An ancient, discredited theory is that light is generated in the eye. [5] A version of this theory has been revived, except, according to its author, that "phosphene lights are [supposed to be] due to the intrinsic perception of induced or spontaneous increased biophoton emission of cells in various parts of the visual system (from retina to cortex)" [24]

Anthropological research

In 1988, David Lewis-Williams and T. A. Dowson published an article about phosphenes and other entoptic phenomena. They argued that non-figurative art of the Upper Paleolithic depicts visions of phosphenes and neurological "form constants", probably enhanced by hallucinogenic drugs. [25]

Research

See also

Related Research Articles

<span class="mw-page-title-main">Retina</span> Part of the eye

The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera.

<span class="mw-page-title-main">Transcranial magnetic stimulation</span> Form of brain stimulation using magnetic fields

Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing magnetic field is used to induce an electric current at a specific area of the brain through electromagnetic induction. An electric pulse generator, or stimulator, is connected to a magnetic coil connected to the scalp. The stimulator generates a changing electric current within the coil which creates a varying magnetic field, inducing a current within a region in the brain itself.

An evoked potential or evoked response is an electrical potential in a specific pattern recorded from a specific part of the nervous system, especially the brain, of a human or other animals following presentation of a stimulus such as a light flash or a pure tone. Different types of potentials result from stimuli of different modalities and types. Evoked potential is distinct from spontaneous potentials as detected by electroencephalography (EEG), electromyography (EMG), or other electrophysiologic recording method. Such potentials are useful for electrodiagnosis and monitoring that include detections of disease and drug-related sensory dysfunction and intraoperative monitoring of sensory pathway integrity.

<span class="mw-page-title-main">Amblyopia</span> Failure of the brain to process input from one eye

Amblyopia, also called lazy eye, is a disorder of sight in which the brain fails to fully process input from one eye and over time favors the other eye. It results in decreased vision in an eye that typically appears normal in other aspects. Amblyopia is the most common cause of decreased vision in a single eye among children and younger adults.

<span class="mw-page-title-main">Visual snow syndrome</span> Visual impairment

Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or coloured dots across the whole visual field. Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches. The condition is typically always present and has no known cure, as viable treatments are still under research. Astigmatism, although not presumed connected to these visual disturbances, is a common comorbidity. As well, migraine and tinnitus are common comorbidities which are both associated with a more severe presentation of the syndrome. TMJ may also be a common comorbidity.

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<span class="mw-page-title-main">Electroretinography</span>

Electroretinography measures the electrical responses of various cell types in the retina, including the photoreceptors, inner retinal cells, and the ganglion cells. Electrodes are placed on the surface of the cornea or on the skin beneath the eye to measure retinal responses. Retinal pigment epithelium (RPE) responses are measured with an EOG test with skin-contact electrodes placed near the canthi. During a recording, the patient's eyes are exposed to standardized stimuli and the resulting signal is displayed showing the time course of the signal's amplitude (voltage). Signals are very small, and typically are measured in microvolts or nanovolts. The ERG is composed of electrical potentials contributed by different cell types within the retina, and the stimulus conditions can elicit stronger response from certain components.

<span class="mw-page-title-main">Blue field entoptic phenomenon</span> Optical phenomenon

The blue field entoptic phenomenon is an entoptic phenomenon characterized by the appearance of tiny bright dots moving quickly along undulating pathways in the visual field, especially when looking into bright blue light such as the sky. The dots are short-lived, visible for about one second or less, and traveling short distances along seemingly random, undulating paths. Some of them seem to follow the same path as other dots before them. The dots may appear elongated along the path, like tiny worms. The dots' rate of travel appears to vary in synchrony with the heartbeat: they briefly accelerate at each beat. The dots appear in the central field of view, within 15 degrees from the fixation point. The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances.

Entoptic phenomena are visual effects whose source is within the human eye itself.

Closed-eye hallucinations and closed-eye visualizations (CEV) are hallucinations that occur when one's eyes are closed or when one is in a darkened room. They can be a form of phosphene. Some people report CEV under the influence of psychedelics; these are reportedly of a different nature than the "open-eye" hallucinations of the same compounds. Similar hallucinations that occur due to loss of vision are called visual release hallucinations.

Neuroprosthetics is a discipline related to neuroscience and biomedical engineering concerned with developing neural prostheses. They are sometimes contrasted with a brain–computer interface, which connects the brain to a computer rather than a device meant to replace missing biological functionality.

<span class="mw-page-title-main">Retinal implant</span>

A retinal implant is a visual prosthesis for restoration of sight to patients blinded by retinal degeneration. The system is meant to partially restore useful vision to those who have lost their photoreceptors due to retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Retinal implants are being developed by a number of private companies and research institutions, and three types are in clinical trials: epiretinal, subretinal, and suprachoroidal. The implants introduce visual information into the retina by electrically stimulating the surviving retinal neurons. So far, elicited percepts had rather low resolution, and may be suitable for light perception and recognition of simple objects.

<span class="mw-page-title-main">Photopsia</span> Presence of perceived flashes of light in ones field of vision

Photopsia is the presence of perceived flashes of light in the field of vision.

<span class="mw-page-title-main">Form constant</span> Recurringly observed geometric pattern

A form constant is one of several geometric patterns which are recurringly observed during hypnagogia, hallucinations and altered states of consciousness.

<span class="mw-page-title-main">Transcranial direct-current stimulation</span> Technique of brain electric stimulation therapy

Transcranial direct current stimulation (tDCS) is a form of neuromodulation that uses constant, low direct current delivered via electrodes on the head. It was originally developed to help patients with brain injuries or neuropsychiatric conditions such as major depressive disorder. It can be contrasted with cranial electrotherapy stimulation, which generally uses alternating current the same way, as well as transcranial magnetic stimulation.

A visual prosthesis, often referred to as a bionic eye, is an experimental visual device intended to restore functional vision in those with partial or total blindness. Many devices have been developed, usually modeled on the cochlear implant or bionic ear devices, a type of neural prosthesis in use since the mid-1980s. The idea of using electrical current to provide sight dates back to the 18th century, discussed by Benjamin Franklin, Tiberius Cavallo, and Charles LeRoy.

<span class="mw-page-title-main">Electrical brain stimulation</span> Form of electrotherapy

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Neurostimulation is the purposeful modulation of the nervous system's activity using invasive or non-invasive means. Neurostimulation usually refers to the electromagnetic approaches to neuromodulation.

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Non-invasive cerebellar stimulation is the application of non-invasive neurostimulation techniques on the cerebellum to modify its electrical activity. Techniques such as transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) can be used.. The cerebellum is a high potential target for neuromodulation of neurological and psychiatric disorders due to the high density of neurons in its superficial layer, its electrical properties, and its participation in numerous closed-loop circuits involved in motor, cognitive, and emotional functions.

References

  1. ↑ Davis, F. A.; Bergen, D.; Schauf, C.; McDonald, I.; Deutsch, W. (1 November 1976). "Movement phosphenes in optic neuritis: A new clinical sign". Neurology. 26 (11): 1100–1104. doi:10.1212/wnl.26.11.1100. PMID   988518. S2CID   32511771.
  2. ↑ Page, N.; Bolger, J.; Sanders, M. (1 January 1982). "Auditory evoked phosphenes in optic nerve disease". Journal of Neurology, Neurosurgery & Psychiatry. 45 (1): 7–12. doi:10.1136/jnnp.45.1.7. PMC   491258 . PMID   7062073.
  3. ↑ Nicholson, Philip T. (2002). "The Soma Code, Part III: Visions, Myths, and Drugs". Electronic Journal of Vedic Studies. 8 (3): 70–92. doi:10.11588/ejvs.2002.3.942.
  4. ↑ Klüver, Heinrich (1966). Mescal, and Mechanisms of hallucinations. University of Chicago Press. p. 70. OCLC   1194424731.
  5. 1 2 Grüsser, Otto-Joachim; Hagner, Michael (February 1990). "On the history of deformation phosphenes and the idea of internal light generated in the eye for the purpose of vision". Documenta Ophthalmologica. 74 (1–2): 57–85. doi:10.1007/bf00165665. PMID   2209368. S2CID   30223977.
  6. ↑ Sellman, TK (2018-03-11). "Phosphenes: Your Own Personal Aurora Borealis". MultipleSclerosis.net. Retrieved 2020-02-02.
  7. ↑ Newton, Isaac. "Laboratory Notebook". cudl.lib.cam.ac.uk. Cambridge Digital Library. Retrieved 9 October 2014.
  8. ↑ Newton, Isaac; McGuire, J. E; Tamny, Martin (2002). Certain philosophical questions: Newton's Trinity notebook. Cambridge University Press. p. 386. ISBN   978-0-521-53066-8. OCLC   728748184.
  9. ↑ "From the library". British Journal of Ophthalmology. 87 (10): 1308. 1 October 2003. doi: 10.1136/bjo.87.10.1308 .
  10. ↑ Savigny, J. B. H. (1838). "Phosphenes ou sensations loumineuses" [Phosphenes or light-hearted sensations]. Archives Générale de Médecine (in French). 3 (2): 495–497.
  11. ↑ Serre, H. Auguste (1853). Essai sur les phosphenes: ou anneaux lumineux de la retine considérés dans leurs rapports avec la physiologie et la pathologie de la vision [Test on phosphenes: or luminous rings of the retina considered in their relation to the physiology and pathology of vision] (in French). Masson. OCLC   1194111898.[ page needed ]
  12. ↑ Brindley, G. S.; Lewin, W. S. (1 May 1968). "The sensations produced by electrical stimulation of the visual cortex". The Journal of Physiology. 196 (2): 479–493. doi:10.1113/jphysiol.1968.sp008519. PMC   1351724 . PMID   4871047.
  13. ↑ Dobelle, W. H.; Mladejovsky, M. G. (1 December 1974). "Phosphenes produced by electrical stimulation of human occipital cortex, and their application to the development of a prosthesis for the blind". The Journal of Physiology. 243 (2): 553–576. doi:10.1113/jphysiol.1974.sp010766. PMC   1330721 . PMID   4449074.
  14. ↑ Cowey, Alan; Walsh, Vincent (2001). "Chapter 26: Tickling the brain: studying visual sensation, perception and cognition by transcranial magnetic stimulation". In Casanova, Christian; Ptito, Maurice (eds.). Vision: From Neurons to Cognition, Volume 1. Gulf Professional Publishing. pp. 411–25. ISBN   978-0-444-50586-6.
  15. ↑ Tehovnik, E. J.; Slocum, W. M.; Carvey, C. E.; Schiller, P. H. (January 2005). "Phosphene Induction and the Generation of Saccadic Eye Movements by Striate Cortex". Journal of Neurophysiology. 93 (1): 1–19. CiteSeerX   10.1.1.326.9609 . doi:10.1152/jn.00736.2004. PMID   15371496.
  16. 1 2 Kanai, Ryota; Chaieb, Leila; Antal, Andrea; Walsh, Vincent; Paulus, Walter (December 2008). "Frequency-Dependent Electrical Stimulation of the Visual Cortex". Current Biology. 18 (23): 1839–1843. doi: 10.1016/j.cub.2008.10.027 . PMID   19026538. S2CID   15466470.
  17. ↑ Kar, Kohitij; Krekelberg, Bart (15 October 2012). "Transcranial electrical stimulation over visual cortex evokes phosphenes with a retinal origin". Journal of Neurophysiology. 108 (8): 2173–2178. doi:10.1152/jn.00505.2012. PMC   3545027 . PMID   22855777.
  18. ↑ Schwiedrzik, Caspar (2009). "Retina or visual cortex? The site of phosphene induction by transcranial alternating current stimulation". Frontiers in Integrative Neuroscience. 3: 6. doi: 10.3389/neuro.07.006.2009 . PMC   2691656 . PMID   19506706.
  19. ↑ Schutter, Dennis J.L.G.; Hortensius, Ruud (July 2010). "Retinal origin of phosphenes to transcranial alternating current stimulation". Clinical Neurophysiology. 121 (7): 1080–1084. doi:10.1016/j.clinph.2009.10.038. PMID   20188625. S2CID   11763513.
  20. ↑ Fuglesang, Christer; Narici, Livio; Picozza, Piergiorgio; Sannita, Walter G. (April 2006). "Phosphenes in Low Earth Orbit: Survey Responses from 59 Astronauts". Aviation, Space, and Environmental Medicine. 77 (4): 449–452. PMID   16676658.
  21. ↑ Tendler, Irwin I.; Hartford, Alan; Jermyn, Michael; LaRochelle, Ethan; Cao, Xu; Borza, Victor; Alexander, Daniel; Bruza, Petr; Hoopes, Jack; Moodie, Karen; Marr, Brian P.; Williams, Benjamin B.; Pogue, Brian W.; Gladstone, David J.; Jarvis, Lesley A. (February 2020). "Experimentally Observed Cherenkov Light Generation in the Eye During Radiation Therapy". International Journal of Radiation Oncology, Biology, Physics. 106 (2): 422–429. doi:10.1016/j.ijrobp.2019.10.031. PMC   7161418 . PMID   31669563.
  22. ↑ Tardif, Jean-Claude; Ford, Ian; Tendera, Michal; Bourassa, Martial G.; Fox, Kim (1 December 2005). "Efficacy of ivabradine, a new selective If inhibitor, compared with atenolol in patients with chronic stable angina". European Heart Journal. 26 (23): 2529–2536. doi: 10.1093/eurheartj/ehi586 . PMID   16214830.
  23. ↑ Grüsser, OJ; Grüsser-Cornehls, U; Hagner, M; Przybyszewski, AW (1989). "Purkynĕ's description of pressure phosphenes and modern neurophysiological studies on the generation of phosphenes by eyeball deformation". Physiologia Bohemoslovaca. 38 (4): 289–309. PMID   2531426.
  24. ↑ Bókkon, István (May 2008). "Phosphene phenomenon: A new concept". Biosystems. 92 (2): 168–174. CiteSeerX   10.1.1.377.2281 . doi:10.1016/j.biosystems.2008.02.002. PMID   18358594.
  25. ↑ Lewis-Williams, J. D.; Dowson, T. A.; Bahn, Paul G.; Bednarik, Robert G.; Clegg, John; Consens, Mario; Davis, Whitney; Delluc, Brigitte; Delluc, Gilles; Faulstich, Paul; Halverson, John; Layton, Robert; Martindale, Colin; Mirimanov, Vil; Turner, Christy G.; Vastokas, Joan M.; Winkelman, Michael; Wylie, Alison (April 1988). "The Signs of All Times: Entoptic Phenomena in Upper Palaeolithic Art [and Comments and Reply]". Current Anthropology. 29 (2): 201–245. doi:10.1086/203629. JSTOR   2743395. S2CID   147235550.
  26. ↑ Lewis, Philip M.; Rosenfeld, Jeffrey V. (January 2016). "Electrical stimulation of the brain and the development of cortical visual prostheses: An historical perspective". Brain Research. 1630: 208–224. doi: 10.1016/j.brainres.2015.08.038 . PMID   26348986.
  27. ↑ Jiang, Linxing; Stocco, Andrea; Losey, Darby M.; Abernethy, Justin A.; Prat, Chantel S.; Rao, Rajesh P. N. (26 September 2018). "BrainNet: A Multi-Person Brain-to-Brain Interface for Direct Collaboration Between Brains". arXiv: 1809.08632 . doi:10.1101/425066. S2CID   52815886.{{cite journal}}: Cite journal requires |journal= (help)


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