Retinotopic distribution, visual latency and orientation tuning of ‘sustained’ and ‘transient’ cortical neurones in area 17 of the cat

SummaryFurther quantitative studies have been made on neurones in area 17 of the cat's visual cortex which were classified as ‘sustained’ or ‘transient’ and ‘simple’ or ‘complex’. ‘Sustained’ cells were relatively more common in the cortical area which receives projections from the central retina, whereas ‘transient’ cells were relatively more common in a cortical area receiving peripheral projections. The distribution of ‘simple’ and ‘complex’ cells was even. ‘Sustained’ cells, both ‘simple’ and ‘complex’, had a longer latency to a stationary, optimum bar at the receptive field centre than ‘transient’ cells. Regardless of whether they were ‘sustained’ or ‘transient’, ‘simple’ cells were more sharply tuned to a specific orientation than ‘complex’ cells. The ‘sustained/transient’ classification is thus independent of the ‘simple/complex’ classification which appears to be based upon properties of cortical origin such as orientation.