In II adult cats, areas 17, 18, 19 as well as the lateral suprasylvian area were separately injected with L-[5-3H] proline and their efferent projections to the frontal cortex were autoradiographically searched. Only area 19 and lateral suprasylvian area showed such projections; terminal sites were localized in the ventral and dorsal banks of the cruciate sulcus and in the adjacent mesial surface of the brain. The possibility that these labeled regions may correspond to the monkey's frontal eye field is discussed.
