The effects of stimulation of trigeminal sensory afferents upon caudate units in cats.

This investigation assessed the influences of trigeminal primary sensory afferents upon caudate neuronal activity in locally anesthetized and chloralose anesthetized cats. Afferents from jaw elevator stretch receptors were stimulated via electrodes in the trigeminal mesencephalic nucleus (Mes 5). Afferents from dental and periodontal receptors were stimulated via electrodes in the inferior dental nerve (IDN). Low intensity electrical stimulation of either locus evoked caudate neuronal responses with Mes 5 being more effective. Higher intensity stimulation of IDN in chloralose anesthetized cats was used to determine if thresholds of trigeminal evoked caudate responses corresponded to thresholds of particular fiber groups in the sensory afferent. In all tested units, neuronal responses were only evoked when stimulation was suprathreshold for both A beta and A delta fibers. These data were discussed in relation to processing of oropharyngeal sensory information within the basal ganglia. Possible implications for bucco-lingual dyskinesias were noted.