NEURONAL FIRING ACTIVITY IN THE LATERAL VESTIBULAR NUCLEUS DURING LOCOMOTION IN THE GUINEA-PIG

The effects of spontaneous locomotor activity on neuronal background firing in the lateral vestibular nucleus was investigated during experiments on decerebrate guinea pigs. The onset of rhythmic muscular activity in the extremities was found to produce a rise in the rate of such discharges, which increased from 10-15 to 100 spikes/sec in most neurons. A higher rate occurred as activity began in the ipsilateral forelimb extensor muscles (the stage corresponding to the end of the swing phase and start of the stance phase in the locomotor cycle). The alterations noted in vestibular neuronal activity during locomotion are thought to ensure the background of high anti-gravity muscle tonus against which rhythmic limb movements take place.