Mechanisms regulating the activity of facial nucleus motoneurones--1. Antidromic activation

The antidromic activation of facial nucleus montoneurones has been studied in acute experiments on cats by means of extra- and intracellular recording techniques. Time and amplitude characteristics of separate components of the antidromic action potential and the after--potentials accompanying it have been analyzed. A correlation is found between the duration of the falling phase of the soma-dendritic component of the action potential, the duration of its after-hyperpolarization and impulse conduction time in the axon. The dendritic origin of after-depolarizing processes is shown. It is concluded that, since there is no recurrent collateral pathway in facial motoneurones, the modulating effect of spike after-potentials on the proper excitability of facial motoneurones acquires great functional significance.