Motoneurone activity in an isolated spinal cord preparation from the adult mouse.

This paper describes an isolated, hemisected preparation of adult mouse spinal cord, in which motoneurones remain viable. At 18-22 degrees C both orthodromic synaptic activation and antidromic invasion of populations of motoneurones could be demonstrated by extracellular recording of ventral root reflexes and ventral horn field potentials. Motoneurones had resting potentials of -55 to -65 mV and input resistances of 5-30 M omega, and, following ventral or dorsal root stimulation or during outward current injection, they generated action potentials which resembled those recorded from adult motoneurones in vivo. Recurrent inhibitory synaptic potentials followed antidromic spikes, demonstrating viability of the Renshaw cell pathway.