This article is about the visual illusion. For the PH3 gas, seephosphine. For the COCl2 gas, seephosgene. For unsaturated phosphorus compounds, seediphosphene andphosphaalkene.
An artist's representation of how some people may see phosphenes by retinal stimulation
Aphosphene is the phenomenon of seeinglight without light entering theeye. The wordphosphene comes from the Greek wordsphos (light) andphainein (to show). Phosphenes that are induced by movement or sound may be associated withoptic neuritis.[1][2]
The most common phosphenes arepressure phosphenes, caused by rubbing or applying pressure on or near the closed eyes. They have been known since antiquity, and described by theGreeks.[5] The pressure mechanically stimulates the cells of theretina. 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 asneeze, laughter, a heavy and deep cough,blowing of the nose, a blow on the head orlowblood pressure (such as onstanding up too quickly or prior to fainting). It is possible these involve some mechanical stimulation of the retina, but they may also involve mechanical andmetabolic (such as from low oxygenation or lack of glucose) stimulation ofneurons of thevisual 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 asmultiple 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 the French physicianHenri Savigny [fr], better known as the ship's surgeon of the wrecked French frigateMéduse.[10] It was first employed by Serre d'Uzes to test retinal function prior to cataract surgery.[11]
Phosphenes have been created by electrical stimulation of the brain, reported byneurologistOtfrid Foerster as early as 1929. Brindley and Lewin (1968) inserted a matrix of stimulatingelectrodes directly into thevisual cortex of a 52-year-oldblind female, using small pulses ofelectricity 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 avisual prosthesis, in this case by using the phosphenes to depictBraille spots.
In recent years, researchers have successfully developed experimentalbrain–computer interfaces orneuroprostheses that stimulate phosphenes to restore vision to people blinded through accidents. Notable successes include the human experiments byWilliam H. Dobelle[13] and Mark Humayun and animal research by Dick Normann.
Experiments with humans have shown that when the visual cortex is stimulated above thecalcarine fissure, phosphenes are produced in the lower part of the visual field, and vice versa.[15]
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 resembleCherenkov radiation.[21]
Phosphenes can be caused by some medications, such asIvabradine.[22]
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 ofretinal 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]
Research has looked intovisual prosthesis for the blind, which involves use of arrays of electrodes implanted in the skull over theoccipital lobe to produce phosphenes. There have been long term implants of this type. Risks, such as infections and seizures, have been an impediment to their development.[26]
A possible use of phosphenes as part of a brain-to-brain communication system has been reported. The system called BrainNet, produces phosphenes usingtranscranial magnetic stimulation (TMS). The goal of the research is to connect thoughtsbrain to brain using a system where signals are detected usingelectroencephalography (EEG) and delivered usingtranscranial magnetic stimulation (TMS). An experiment was conducted with five different groups, each containing three people. The subjects were split into two groups. Two subjects functioned as the senders, and were connected to EEG electrodes, and a third person functioned as the receiver, who wore the TMS helmet. Each person was stationed in front of a television screen with aTetris-style game. The senders had to determine if there was a need to rotate the falling blocks, but without the ability to rotate them – only the receiver was able to perform this operation. At the edges of each screen, were two icons with two flashing lights in two different frequencies, (one at 15 Hz and the other at 17 Hz). The sender focused on one icon, or the other to signal that the block should be rotated to the right or the left. TheEEG produced a unique signal, which was transmitted to the TMS helmet of the receiver, who perceived phosphenes which differed for the 15 Hz and 17 Hz signal, and rotated the block in the relevant direction. The experiment achieved 81% success.[27]
^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.PMID988518.S2CID32511771.
^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.
^Klüver, Heinrich (1966).Mescal, and Mechanisms of hallucinations. University of Chicago Press. p. 70.OCLC1194424731.
^abGrüsser, 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.PMID2209368.S2CID30223977.
^Newton, Isaac."Laboratory Notebook".cudl.lib.cam.ac.uk. Cambridge Digital Library. Retrieved9 October 2014.
^Newton, Isaac; McGuire, J. E; Tamny, Martin (2002).Certain philosophical questions: Newton's Trinity notebook. Cambridge University Press. p. 386.ISBN978-0-521-53066-8.OCLC728748184.
^Savigny, J. B. H. (1838). "Phosphenes ou sensations loumineuses" [Phosphenes or light-hearted sensations].Archives Générale de Médecine (in French).3 (2):495–497.
^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.CiteSeerX10.1.1.326.9609.doi:10.1152/jn.00736.2004.PMID15371496.
^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.PMID20188625.S2CID11763513.
^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.PMID2531426.
^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.S2CID52815886.{{cite journal}}:Cite journal requires|journal= (help)
