Phosphene
Phosphenes (from the Greek φῶς “light” and φαίνειν “appear”) are perceptions of light that are not generated by light, but by other stimuli on the eye , the optic nerve or the visual cortex in the brain .
Phosphene can be generated by applying pressure to the eyeball (pressure phosphene), as the cell membranes are stretched and the subsequent influx of sodium ions creates a depolarization that is perceived as a stimulus. In phosphene tonometry , the force that is necessary to generate a phosphene is used to infer the intraocular pressure .
Direct electrical stimulation or the influence of electromagnetic fields can also generate phosphenes ( magnetophosphenes ). The latter happens, for example, with transcranial magnetic stimulation (TMS) and can be used for diagnostic examinations .
Phosphenes also occur in abnormal changes in the brain such as migraine attacks and can occur as a side effect of medication.
In the 18th century, “phosphene parties” were popular at times, in which the participants sat in a circle, held hands and let electricity supplied by an electrostatic generator run through the group in order to experience phosphene perceptions.
See also
literature
- Robert F. Schmidt: Physiology of humans: With pathophysiology . 30th edition. Springer, 2007, ISBN 978-3-540-32908-4 , pp. 18 .
Individual evidence
- ↑ Anselm Kampik: Ophthalmological diagnostics . Georg Thieme Verlag, 2003, ISBN 978-3-13-130661-6 , p. 66 .
- ↑ Jearl Walker : The Flying Circus of Physics . Oldenbourg Wissenschaftsverlag, 2007, ISBN 978-3-486-25478-5 , p. 159 .