Unitary correlates of linguo-pharyngeal events in a dyskinetic rat model.

1. The hypoglossal nucleus unitary correlates of ketamine- and electrically induced tongue contractions and swallowing events were recorded and compared in stereotaxically mounted rats. 2. Very few of the units recorded could be identified as motoneurons by antidromic invasion through electrical stimulation of the hypoglossal nerve. 3. The sample consists of 109 units, 2/3 of which were located in the retrusor pool and 1/3 in the protrusor region. 4. Linguo-pharyngeal events were considered to be electrically induced if they followed consistently, and with a relatively fixed latency, a single electrical pulse delivered to the superior laryngeal nerve, and ketamine-induced if no such time-locked sequence existed or if they occurred in the absence of electrical stimulation. 5. No differences could be discovered between the two types of linguo-pharyngeal events whether they were compared at the polygraphic or the unitary level. 6. These findings suggest that pharmacologically (ketamine)-induced dyskinetic activity does not differ from comparable motor patterns induced by classical electrophysiological means.