Projections from the pericruciate cortex to the nucleus of Darkschewitsch and other structures at the mesodiencephalic junction in the cat.

After injecting a mixture of tritiated amino acids into various regions of the frontal cortices of cats, autoradiograms of the mesodiencephalic junctional region were processed. When the injections were placed in the lateral part of the motor area of the hand or arm regions, silver grains were manifested in the nucleus of Darkschewitsch (ND) in its whole rostrocaudal extent, and they were observed also in the ventrolateral part of the anterior pretectal nucleus (PA) and in the caudal portion of the posterior pretectal nucleus (PP). Following injections made into the medialmost part of the anterior sigmoid gyrus (area 6), medial to middle parts of the posterior sigmoid gyrus, the proreal gyrus or the medial surface of the frontal cortex (area 32), no silver grains were observed in ND, PA and PP.