Long-term potentiation of the late NMDA-dependent components of neuron responses in the cat motor cortex to stimulation of the direct cortical input from field 5 of the parietal cortex.

Bicuculline-filled microelectrodes were used to record responses to weak stimulation of the parietal cortex in field 5 of the motor cortex of anesthetized cats, and revealed late excitatory responses of neurons similar to those seen in the motor cortex of conscious cats in response to conditioned stimulation of the parietal cortex triggering a conditioned reflex consisting of placing the paw on a support. Tetanic stimulation of the parietal cortex (10-20 sec, 100 Hz) in the same conditions evoked long-term potentiation of late responses, resulting in the formation and enhancement of responses, along with decreases in the latent period of responses.