Behavioral and morphological effects of oculomotor nucleus lesion on abducens internuclear neurons in the cat

The activity of identified control and injured abducens internuclear neurons was recorded during spontaneous eye movements in the alert cat. From 2 days following the electrocoagulation of the contralateral oculomotor nucleus, abducens internuclear neurons showed a quick fatigability during eye fixations not observed in controls. Discharge rate during saccades started after the beginning of the eye movement and showed a fast exponential-like decay. These abnormal responses were not further recorded from 20 days following the lesion. Morphological studies indicated that 90% of the abducens internuclear neuron population disappeared 2 months following the lesion and showed no sign of recovery one year later.