The vestibular-basal ganglia connection: balancing motor control.

Connections between the vestibular system and the basal ganglia have been sporadically studied over the last century. Electrophysiological studies of field potentials in animals have shown that most areas of the striatum respond to electrical vestibular stimulation while human studies isolated responses to vestibular stimulation to the putamen of the striatum. Protein studies have shown inconsistent results regarding changes in receptor levels of a number of receptor types. Recent tracer studies identified a pathway between the vestibular nucleus and the striatum via the thalamus, completely bypassing the cortex. Vestibular sensory input is represented in the part of the striatum - the dorsolateral striatum - where fibres from the sensorimotor areas terminate. It is therefore possible that vestibular signals are used together with other sensorimotor inputs in the striatum for body and limb control. The combination of electrophysiological results, changes in protein levels and tracer studies have led to the idea that the dorsolateral striatum is likely to be the main input area for vestibular signals in the basal ganglia and these will have an influence on motor control. This may have clinical implications in the treatment of basal ganglia disorders and other movement disorders.