Contribution of the cortico-claustral loop to receptive field properties in area 17 of the cat.

The contribution of the cat's claustrum to the response properties of cells in area 17 was studied by destroying the left claustrum and examining receptive field properties of cells in both the left and right area 17. For each cell we assessed sharpness of orientation tuning, degree of direction selectivity, length summation, end-stopping, ocular dominance, responsiveness, and several other properties. On the lesioned side, 462 cells were studied, and on the control side, 636 cells. All cats showed a reduction in the number of end-stopped cells in area 17 on the side of the lesion. This was particularly marked in layers 2 + 3 and 4, where end-stopped cells are normally most abundant. In the control hemisphere, 43% of the sample from these layers showed at least moderate end-stopping whereas, in contrast, only 21% exhibited this degree of end-stopping on the side of the lesion. There was no obvious change in other response properties. We conclude that one function of the cat's claustrum is to help regulate the length selectivity of cells in area 17.