[Mechanisms of motor neuron interaction in the isolated spinal cord of rat pups].

Interactions between lumbar motoneurons were studied by intracellular recording of responses to stimulation of ventral roots and intracellular HRP injection in isolated spinal cord preparations of immature (9-14 days old) rats. Ventral root-evoked electrotonic potentials in individual motoneurons were due to interconnections with few other motoneurons and could not elicit spike potentials. Direct chemical excitatory interactions of motoneurons were also found which may occur via axon collaterals. Differences between individual motoneurons in the mode of responses to ventral root stimulation, probably, depend on their functional specialization.