Electrophysiological study on the corticoreticular projection neurons of the cat.

Thirty-two motor cortical neurons of the cat which project on medullary reticular formation (RF) were electrophysiologically classified into 3 groups, i.e., 22 slow PT-RF neurons (collateral projections to RF from slow pyramidal tract (PT) neurons), 6 fast PT-RF neurons (those from fast PT neurons) and 4 RF (non-PT) neurons without any relation to PT neurons. Firings of slow PT-RF and RF (non-PT) neurons elicited by thalamic stimulation showed close correlation to the surface negative component of cortical evoked potentials. It was suggested that activities of these neurons are controlled mainly by excitatory thalamic inputs onto the distal and superficial part of their apical dendrites.