[Effects of distal axotomy on field potentials of the external oculomotor nucleus in the waking cat].

The electrophysiology of abducens nucleus antidromic field potentials from onset of peripheral axotomy up to reinnervation has been studied in the alert cat. Nerve section induced a reduction of 80% in the amplitude of the antidromic field potential. This reduction began from 2 to 5 days after axotomy and returned to control values from 20 to 30 days later, in parallel with recovery of oculomotor function. During the critical chromatolytic period, the latency of the antidromic potentials increased, while the amplitude of the antidromic field potential could be easily modified by adequate visual and/or vestibular stimulation. In contrast to control motoneurons, axotomized cells showed a noticeable variability in their activation latency, as well as a higher threshold for the antidromic invasion of the IS-SD compartments.