[Date Prev][Date Next][Thread Prev][Thread Next]   [Date Index] [Thread Index] [Author Index

Pressure phosphenes...



Hi Folks,
 
From the "And now for something completely different" files...
 
I have been researching the visual phenomenon of pressure phosphenes. These are the mini light-shows the brain interprets when one presses on one's closed eyes. I first discovered this phenomenon as a child, rubbing sleepy eyes with my fists and, of course, asked my father about it... He said, at the time, that no one knew what caused the pattern to be generated the way it was, but admitted he had experienced it himself and we compared phosphene patterns, which were identical (black and white geometrical designs which coalesce with one another in a big patchwork of different geometries). The reason I bring it up here is because at a routine eye exam recently I finally discovered the name for the phenomenon (phosphene) and the doctor said that it's very individual, that no two people will have the same pattern, like fingerprints. Well, since I knew this could not be the case, I decided to research it...
 
I found a great website:
http://www.neuroscience.med.utah.edu/Faculty/Bressloff.html
They are using the phenomenon to try and understand how the brain processes visual information. The site has some artistic renderings of various phosphene patterns (none of which match the kind I generally experience--I don't get the central vortex they show in all of their pictures).
 
As they discuss on the site, pressure phosphenes are very similar to the kind of visual disturbance that precedes a true migraine headache, which I have only experienced twice in my life, and my father experienced once. We both experienced the same kind of geometric patterns that were typical of our identical phosphene pattern, except superimposed on the normal visual field. At times, the visual field would be blank in small areas, except for the geometric pattern, almost like the holodeck on the second Star Trek series, when it begins to malfunction and the grid pattern of the actual room becomes visible in patches.
 
I'm curious about this notion that "no two people have the same pattern" statement of the eye doctor, given that I know of one person who saw the same patterns as I did. So I thought a little survey was in order, for whoever is interested.
 
Just to keep this more on topic; I noticed on the website, mentioned  above, that the report describes several times how the dynamical models being used to analyze the situation give limited useful information or the information they do give must be taken with caution because...  They are also not addressing what, to me, seem like probable useful avenues of information... For example; I wonder if people born blind see pressure phosphenes? If not, what about people who were blinded after the visual cortex of the brain developed? Do their patterns differ from non-blind people? Do the patterns each person "sees" change over time? With physiological changes such as pregnancy? High blood pressure? Puberty?
 
Any ideas from the list?
 
Judith
BioTheory: An E-Journal of General Science in the Rosennean Complexity Paradigm http://www.rosen-enterprises.com/RobertRosen/BioTheoryLaunch.htm
Website address: http://www.rosen-enterprises.com/