[Quantitative characteristics of the cortex area 4y associative projections to subfields of the sensomotor and parietal cerebral cortex in cat].

The ipsilateral association connections of the motor cortex area 4y after its local electrolytic lesion in the cat were studied using Nauta-Gigax method. Relative quantitative distribution of the efferent association fibers projecting from area 4y to the somatosensory regions I and II, motor and parietal cortex, was determined. It was shown that the major projections from area 4y are directed to area 2pri (secondary somatosensory zone) and to area 5ab. Sparse degenerating fibers were found in the areas 1, 2, 3a and 3b of the primary somatosensory cortical zone. No efferent fibers were traced projecting from area 4y to the areas 4fu, 4sfu, 6aa, 6ab and 6ifu. It is suggested that the morphological basis of the motor reactions implemented by area 4y is formed not by fundal (4fu, 4sfu, 6ifu) or premotor (6aa, 6ab) subfields, but by the areas 2pri and 5ab which are involved to a maximum degree.