Light level induced reorganization of cat's lateral geniculate nucleus receptive fields: a spatiotemporal study

The spatiotemporal organization of receptive fields (RF) of the cat’s lateral geniculate cells was investigated under several scotopic and mesopic light adaptation levels, using stationary and moving light stimuli. A given adaptation level was reached by changing of either the diffuse background or the adapting central spot intensity. Both methods gave the same qualitative results. The RFs were prominently reorganized after dark adaptation. Under such conditions, the central response area was enlarged and the classic excitatory and inhibitory surrounds were hardly visible in most cases. A minimum light level was needed for developing classic surrounds. Both inhibitory and excitatory surrounds changed their spatial positions simultaneously at higher light adaptation levels. ON- and OFF-center cells changed their spatiotemporal organization similarly, thus indicating similar underlying mechanisms.