The visual areas in the splenial sulcus of the cat.

1. The extreme periphery of the visual field is represented in the upper wall of the splenial sulcus where the sulcus is horizontal, and in its anterior wall more posteriorly where the sulcus runs downwards and laterally. About half the cells whose fields lie between 50 and 90 degrees from the area centralis have a sharply horizontal preferred orientation.2. Beyond the lateral edge of visual I there is a narrow band of visual cortex in which the receptive fields return towards the area centralis as one moves 1-1.5 mm laterally. Their receptive fields are usually about 20-30 degrees degrees across, but all orientations are found. The more central fields may be binocular and those at the area centralis may be as small as 1 degrees in diameter.3. This band has been called the splenial visual area. It does not seem to have properties corresponding to those of visual II nor of visual III.