[Identification of transcallosal excitatory monosynaptic responses]

Criteria of identification of transcallosal monosynaptic responses recorded extracellularily in the sensorimotor cortex to stimulation of the homotopic area of the contralateral hemisphere were studied in unanaesthetized, non-immobilized rabbits. It was found that major criteria by which a monosynaptic response differs from an antidromic one, are: absence of response blocking by a background impulse (the collision method), and comparatively low up to 200 Hz maximal frequency of paired stimuli reproduction. Criteria of a monosynaptic response, as compared to a polysynaptic one, are its stability, its low variability (0.1-0.2 msec with latency up to 10 msec) and relatively high (not less than 70-100 Hz) maximal frequency of paired stimuli reproduction.