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Abstract

This chapter discusses the physiological properties of the anterior ectosylvian visual area (AEV) of the cat. AEV area was found and described practically simultaneously by Olson and Graybiel. The cells in AEV area exhibit extraordinary visual properties. They are particularly sensitive to small stimuli moving at a fairly high speed in a particular direction in a rather large receptive field. Movement opposite to the preferred direction causes an inhibition of neuronal activity. Another peculiar feature of the AEV cells is their very high directional selectivity (DS). The proportion of direction selective cells is higher in the AEV than in any other feline visual area. The role of the AEV in orienting movement is supported by its sensitivity to small flashing spots, or to the on or off effect of stationary light stimuli. The output of the AEV towards the frontal eye fields and the limbic system provides further evidence for the participation of AEV in eye movements and in limbic functions.