Single unit responses to visual stimuli in cat cortical areas 17 and 18. I.--Responses to stationary stimuli or variable intensity
Galletti, C.; Maioli, M.G.; Squatrito, S.; Riva Sanseverino, E.
Archives Italiennes de Biologie 117(3): 208-230
1979
ISSN/ISBN: 0003-9829 PMID: 508041 Document Number: 142526
Single unit responses to light increments of stationary stimuli were recorded from the visual cortex (areas 17 and 18) of locally anesthetized, Flaxedil-paralyzed and artifically ventilated cats. Since complex and hypercomplex cells gave a very weak on-off response, if any, to a stationary stimulus, the present investigation concerns only the activity of non-oriented cells, simple cells and geniculo-cortical (GC) fibers. These units increase their firing rate over a range of light stimulus intensity of 2.6 .+-. 0.6 log units, 1.7 .+-. 0.6 log units and 2.1 .+-. 0.5 log units, respectively. The neural responses of non-oriented cells and simple cells and GC fibers depend on the intensity of both stimulus and adaptive background, that is on the contrast of the visual stimulus. Different levels of background illumination influence the contrast threshold response of simple cells. An attempt is made to relate the neurophysiological data in the cat to other psychophysical data of others in the cat and in man.