What is phosphen?
phosphen is an optical phenomenon that is characterized by the perception of light when there is no light entering into the eye. It is an entoptic phenomenon, which means that its source lies in the eye or the visual system itself. Phosphen is most often induced by some direct stimulation of the retina, whether mechanical, magnetic or electrical. Random discharge of the electrical signal from one cell in the visual system can also cause phosphen.
In addition to the aforementioned causes, it is not uncommon for this phenomenon to experience someone who has long been without a visual stimulus. This was provided by phosfen the nickname "prison cinema". People who are under the influence of hallucinogenic drugs also state that they see these types of lights, but should not be confused with hallucinations that take place in the brain rather than in the eye.
Pressure phosphanes are the most common type, and it occurs when mechanical pressure is placed on the retina, for example by eye shaking. Pressure phosphen usually persists only when wiping the eyes and for a short time after. These effects were subjected todescribed by ancient rivers and Isaac Newton. Another common phosphen associated with this first type is the species that happens in the morning in the head or strong sneezing. When we see "stars" in these situations, it is partly due to retinal stimulation and stimulating other areas of the visual system, including the visual cortex of the brain.
phosphens that are electrically or magnetically induced are less common. Electrically induced phosphens usually occur only in controlled situations and the first were created in this way in 1928. Recently, scientists have developed methods for electrically production of phosphanes in those who have been blinded - - as a result of accident - as a result of the accident, whose brains are still able to process visual information.
Intensive magnetic fields were also known to produce phosphanes. The procedure called transcranial magnetic stimulation is one of the ways to use magnetic fields to excite nerve cells in the brain to form phosphens. Different partEven the visual system can be stimulated depending on where and how the magnetic field is located. It has also been reported that astronauts sometimes experience phosphans in space, probably due to the higher level of radiation present in space compared to the ground.