โ Scribed by J. Bullier; M. E. McCourt; G. H. Henry
No coin nor oath required. For personal study only.
The functional characteristics of the feedback connections from areas 18 and 19 to area 17 in the cat have been examined with electrophysiological techniques. The experiments involved single unit recording in laminae 2 and 3 of area 17 while stimulating electrically a small region of area 18 or 19. It was found that a precise retinotopic correspondence between the sites of recording and stimulation was necessary before neurons of area 17 could be activated by electrical stimulation in extrastriate areas. Latencies were long compared to those obtained after stimulation of the optic radiation. The mean latency for orthodromic drive from area 19 was 10.4 ms and 6.1 ms from area 18, suggesting that the conduction velocities in these pathways are of the order of 1 m/s. The jitter of the latency after repeated orthodromic stimulation was often shorter than 0.3 ms, indicating that a large number of the sampled neurons received a direct drive from area 18 or from area 19. The functional properties of neurons driven from area 19 were different from those of cells driven from area 18. Thus, most striate neurons orthodromically driven from area 19 were of the SH and S type whereas the cells activated by area 18 stimulation belonged to the C and B categories.
๐ SIMILAR VOLUMES
The horizontal organization of iso-orientation bands in the cat's visual cortex has been investigated with the 14C-Deoxyglucose method (Sokoloff et al. 1977). Our findings suggest that in areas 17 and 18 the network formed by the bands representing one orientation comprises three basic patterns. Mos