Adaptation of PMLS neurons to prolonged optic flow stimuli.

Changes in neuronal responses during and after adaptation to prolonged optic flow stimulation were investigated by extracellular single-unit recording in the posteromedial lateral suprasylvian area (PMLS) of the cat. In comparison with translation stimuli, the complex optic flow patterns (radiation and rotation) produced more pronounced adaptation and after-effects by inducing larger response reduction, and altered the direction selectivity of many neurons obviously as well. Generally, the adaptation effects were direction-specific for radiation/rotation, but independent of the direction of test stimulus for translation. These results suggest that PMLS may play an important role in the perception of motion after-effects to complex optic flow fields, while the adaptation to simple translation might be generated at a relatively earlier level of the visual system.