The primate superior colliculus and the shift of visual attention.
نویسندگان
چکیده
seem to be affected very dramatically and can subserve foveal vision as well. Have you any ideas on what this cortical input is doing as well as on the anatomy of the lower layers of the colliculus about which you haven't talked but which may clarify some things? LUND: That really is puzzling. I think it highly unlikely that there is a major direct optic projection to the rostral colliculus. It cannot be demonstrated by light or electron microscope degenerative methods, nor can it be shown by autoradiographic labeling methods. Assuming that your cortical lesions are complete and that your electrodes really are in the superior colliculus and not in adjacent .pretectal nuclei, one has to postulate that there may be indirect optic influences via possible pretectum-collicular or geniculate-collicular pathways. Alternatively, there could be a very small number of direct optic terminals to the region which are below the resolution of detection by the anatomical methods used but which, are sufficient to produce unit activity. Your comments regarding the relatively normal response patterns in the colliculus after cortical lesions suggest to me two possibilities—either your experimental situation does not exploit the normal activity parameters of the corticotectal pathway, or the widely assumed anatomical dogma that the size of a pathway bears a direct relation to its magnitude of influence is mistaken. With regard to the last, I think it would be very valuable to test the effects of cortical lesions in monkeys and rats (or ground squirrels) under absolutely identical experimental conditions. As is described here, these animals show marked differences in the relative sizes of the two pathways (retinotectal and corticotectal) and one might expect that this should be reflected in functional differences. The deep layers with the possible exception of part of the stratum griseum intermedium do not receive a projection from visual cortical areas. This does not, of course, mean that they do not respond to more indirect visual influences.
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ورودعنوان ژورنال:
- Investigative ophthalmology
دوره 11 6 شماره
صفحات -
تاریخ انتشار 1972