Visual cortical neuron responses to drifting sine-wave gratings in rabbits

Neurons of area 17 (V1) in rabbits were stimulated with drifting sine-wave gratings. Animals were anesthetized and paralyzed under conventional methods to record action potentials of single cells using tungsten-in-glass micro-electrodes. Neurons responded in modulatory or unmodulatory patterns depending on whether cells were of the simple or complex type, respectively. In the spatial domain, most cells were Low-Pass and Band-Pass, with no recordings of High-Pass units. In the temporal domain, Low-Pass, Band-Pass and High-Pass behaviours were found. Rabbits appeared to exhibit all types of pattern responses found in other foveate mammals, including special-complex and end-stopping units. However, in the majority of cells, there was a shift towards the lower end of the spatial frequency spectrum. For instance, the optimal spatial frequency was in the vicinity of lc/d while in the temporal domain, some units responded optimally at 10 c/s. In conclusion, it appears that rabbit cortex contain neurons which are selective for spatial frequency in a manner comparable to that seen in cat and monkey.