Visual responses of neurones in the second visual area of flying foxes (Pteropus poliocephalus) after lesions of striate cortex

1. The first (V1) and second (V2) cortical visual areas exist in all mammal s. However, the functional relationship between these areas varies between species. While in monkeys the responses of V2 cells depend on inputs from V 1, in all non-primates studied so far V2 cells largely retain responsivenes s to photic stimuli after destruction of V1. 2. We studied the visual responsiveness of neurones in V2 of flying foxes a fter total or partial lesions of the primary visual cortex (V1). The main f inding was that visual responses can be evoked in the region of V2 correspo nding, in visuotopic co-ordinates, to the lesioned portion of V1. ('lesion projection zone'; LPZ). 3. The visuotopic organization of V2 was not altered by V1 lesions. 4. The proportion of neurones with strong visual responses was significantl y lower within the LPZs (31.5%) than outside these zones, or in non-lesione d control hemispheres (>70%). LPZ cells showed weak direction and orientati on bias, and responded consistently only at low spatial and temporal freque ncies. 5. The data demonstrate that the functional relationship between V1 and V2 of flying foxes resembles that observed in non-primate mammals. This observ ation contrasts with the 'primate-like' characteristics of the flying fox v isual system reported by previous studies.