what is the mechanism behind it.i know that in the case of posterior retinal detachment it is caused because 'floaters'. what could be the cause here?
2007-03-27 06:49:37 · 3 answers · asked by rara avis 4 in Science & Mathematics ➔ Medicine
also if you look at a source of bright light for too long, this phenemena occurs. how is that explained if photopsia ,in mechanism has nothing to do with the eye?
2007-03-28 02:28:06 · update #1
Photopsia doesn't occur in the eye. It occurs in the brain. All roots of perception is neurological. If there is unusual electrical activity, changes in metabolism or direct nerve stimulation of certain types of secondary processing neurons in the parietal and temporal lobes. It will be perceived by the individual as what ever those affected nerves usually transmit. i.e., flashes of light, or colors. This information may come from the primary or secondary visual cortex, but it may also come from abberant stimualtion of the processing cortex or from ligands binding to receptors (i.e. LSD).
2007-03-27 07:03:39 · answer #1 · answered by misoma5 7 · 0⤊ 0⤋
Classic migraines are often preceded by an "aura," which might involve a visual disturbance. These "scotomas" are described as flashy, jagged blind spots near the center of the vision.
As for their mechanism, it's caused by an automatic firing of neurons in the visual cortex of the occipital lobe of the brain. This pattern of nerve activity is called a "depression of leo," named after the physician who first described the phenomena. The blind spot correlates with the area of affected visual cortex.
The pain of migraine, on the other hand, is caused by vasospasm of the arteries in the brain and its lining.
2007-03-27 14:32:21 · answer #2 · answered by Intrepyd 5 · 0⤊ 0⤋
There's a new development in migraine therapy:
http://www.neurologyreviews.com/feb04/nr_feb04_foramen.html
2007-03-27 19:36:38 · answer #3 · answered by Anonymous · 0⤊ 0⤋