PLASTICITY IN VESTIBULAR AND SPINAL CIRCUITS AFTER HEMILABYRINTHECTOMY IN THE FROG

Removal of the labyrinthine organs on one side results in static and d ynamic disturbances. Some functional recovery is seen in frogs over ti me. Electrophysiological studies of the isolated brainstem and/or spin al cord of hemilabyrinthectomized frogs demonstrate changes in vestibu lar and spinal circuits. Comparison of the time courses of these chang es with the known time course of postural recovery excludes changes in the vestibular nuclei as an explanation for the initial postural reco very process. Selective labyrinthine lesion suggest a causal link betw een utricular lesion, postural deficit, spinal plasticity and postural normalization.