An isolated mammalian brainstem-spinal cord preparation suitable for the investigation of descending control of motor activity.

An in vitro, hemisected brainstem-spinal cord preparation which allows bulbo-spinal interactions to be investigated, has been developed using 25-33 g golden hamsters. Spinal reflexes showing both monosynaptic and polysynaptic components were recorded from the lumbar ventral roots following stimulation of the corresponding dorsal roots. Trains of conditioning stimuli delivered to the caudal region of the medulla caused inhibition of the monosynaptic component and potentiation of the polysynaptic component of the spinal reflex.