cs012136@cs.brown.edu (Garth Shaneyfelt) (04/18/91)
A little while ago someone posted a reference to a series of experiments involving placing a wire mesh on the occipital lobe of blind persons which allowed them to "see" a 3X3 grid. Does anyone know where the article/report was published or what the name of the article was? I'm designing a major in CogSci/CS/Vision and would like to start collecting a library of pertainent info. Thanks in advance -Arioch
rowe@pender.ee.upenn.edu (Mickey Rowe) (04/19/91)
In article <72559@brunix.UUCP> cs012136@cs.brown.edu (Garth Shaneyfelt) writes: >A little while ago someone posted a reference to a series of >experiments involving placing a wire mesh on the occipital lobe of >blind persons which allowed them to "see" a 3X3 grid. > Thanks in advance > -Arioch Are you sure that you're remembering this correctly? It sounds a bit like bad science fiction to me. I've spoken to a neurologist who performs cortical stimulation on epileptic patients prior to surgery, and he says that direct stimulations lead (sighted patients) to see irregular blobs of light that are essentially uncontrollable (that is the experimenter has little control over the size, shape, and location of the percept). I strongly suspect that what you are thinking of is an experiment where a set of dull plastic pins was connected to a camera that caused the pins to vibrate against the persons back. In this setup the frequency at which the pins vibrated was proportional to the intensity of light at the corresponding part of the camera head. Subjects could learn to discriminate crude objects with such a system. Does this sound familiar? (I'm sorry, I tried to find a reference just now, but I was unsuccessful.) Mickey Rowe (rowe@pender.ee.upenn.edu)
minsky@media-lab.media.mit.edu.MEDIA.MIT.EDU (Marvin Minsky) (04/19/91)
In article <41524@netnews.upenn.edu> rowe@pender.ee.upenn.edu (Mickey Rowe) writes: >In article <72559@brunix.UUCP> cs012136@cs.brown.edu (Garth >Shaneyfelt) writes: >>A little while ago someone posted a reference to a series of >>experiments involving placing a wire mesh on the occipital lobe of >>blind persons which allowed them to "see" a 3X3 grid. >> Thanks in advance >> -Arioch > >Are you sure that you're remembering this correctly? It sounds a bit >like bad science fiction to me. I've spoken to a neurologist who >performs cortical stimulation on epileptic patients prior to surgery, >and he says that direct stimulations lead (sighted patients) to see >irregular blobs of light that are essentially uncontrollable (that is >the experimenter has little control over the size, shape, and location >of the percept). > It was good science. Look at the book, @i[Visual Prosthesis,] Academic Press, 1971, pp. 315-319. A neurosurgeon named Brindley implanted an 8X8 array of inductively coupled electrodes on the occipital cortex of a woman who had become blind because of bilateral retinal detachments (a thoroughly peripheral injury that almost surely left her cortex in normal condition). The pad was under the skull and, I think, under the dura mater, but I'm not sure of the latter. Of the 64 electrodes, as I recall (I can't find the book here) about 8 failed and about 8 hurt -- presumably because of stimulating nerves in the pia mater -- but the remaining 48 electrodes produced images which she described as being like half a matchstick at arm's length. And they were indeed arranged topographically, so that Brindly was able to produce various recognizable patterns. One deficiency was that parts of the fovea were missed because of lying in a sulcus -- space between convolutions. Brindley did not attempt to push his silicone pad into that fissure. In fact he did not want to risk any serious brain injury, so the device was removed after a few days, as I recall, because of fear that the implant might cause irritation and scarring. Because of the lawyers and ethicists, no such experiment could be done now, or (?) ever again. The lady actually volunteered for the experiment because of her long interest in neuroscience! But no hospital would now cooperate, I think. Last word. When Brindley did the experiment in the late 60s Warren McCulloch told me that if I wanted to do something like it, it must be done quickly because in later years it would become ethically and politically impossible. I thought he was being depressed or something, but evidently he was just correctly predicting that trend.
doug@eris.berkeley.edu (Doug Merritt) (04/29/91)
In article <5677@media-lab.media.mit.edu.MEDIA.MIT.EDU> minsky@media-lab.media.mit.edu (Marvin Minsky) writes: > Last word. When Brindley did the experiment in the late 60s Warren >McCulloch told me that if I wanted to do something like it, it must be >done quickly because in later years it would become ethically and >politically impossible. I thought he was being depressed or >something, but evidently he was just correctly predicting that trend. For that matter, if you want to do such an experiment with chimpanzees or any other animal, perhaps you'd better do it quick, given the current pressures to outlaw animal experimentation! (I devoutly hope that this is not the trend of the future, but cynicism sometimes makes me think that it is.) Hmm, is Karl Pribram having such difficulties? Doug -- -- Doug Merritt doug@eris.berkeley.edu (ucbvax!eris!doug) or uunet.uu.net!crossck!dougm