PROJECTION PATTERN OF SINGLE CORTICOCORTICAL FIBERS FROM THE PARIETALCORTEX TO THE MOTOR CORTEX

ARBORIZATION Of Single corticocortical (CC) axons projecting from the parietal cortex to the motor cortex (Mx) was analysed using an intraax onal staining technique in the cat. Stem axons arising from cell bodie s in area 5 ramified repeatedly into numerous terminal branches in the Mr, forming 2-6 patches (0.2-0.8 mm in diameter) separated by a termi nal-free gap. Axon terminals were distributed mainly in layers II and III and sparsely in layers V, VI and I. This feature is quite similar to that of thalamocortical axons and other corticocortical fibres. Thu s the patchy organization may be a basic input structure for afferents of the Mr and play a role in generation of adequate motor output patt erns in the Mr.