title: Depression of an inhibitory reflex, the masseteric silent period, in recovering alcoholics.
abstract: Because inhibitory deficits may contribute to motor incoordination of alcoholics, we proposed that the duration of the masseteric silent period (SP), an inhibitory reflex, might be shorter in alcoholics (ALs) than in nonalcoholics (NAs). To test this hypothesis, we measured the SP in a racially mixed group of 12 ALs and 12 NAs matched for age (31-49 years) and sex. All subjects were normotensive, had full dentition, and reported no major medical problems. Sensory and motor conduction velocities of the anterior tibialis, ulnar, and medial nerves were measured for each subject, and were not different in ALs and NAs. Jaw jerk and SP were evoked by tapping the chin manually with a rubber hammer containing a circuit to trigger the oscilloscope display of the masseter EMGs. Averaged mean latencies and durations of the SPs were not significantly different between the right and left masseters. SP latencies were significantly (0.7 msec) shorter in ALs than NAs (p < 0.01). The mean SP duration for ALs (13.9 +/- 1.6 msec) was also significantly shorter than that of the NAs (24.4 +/- 2.4 msec; p < 0.001). Results support the hypothesis that chronic alcoholism may interfere with inhibitory mechanisms in the CNS.
authors.affiliation: Research Institute on Addictions, State University of New York at Buffalo 14203, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Vernon
authors.forename: J A
authors.initials: JA
authors.lastname: Hirsch
authors.forename: B
authors.initials: B
authors.lastname: Bishop
authors.forename: R B
authors.initials: RB
authors.lastname: Cowan
authors.forename: J L
authors.initials: JL
authors.lastname: York
mesh_terms: D000328:Adult; D000437:Alcoholism / Q000503:physiopathology / Q000534:rehabilitation*; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008406:Masseter Muscle / Q000294:innervation*; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012026:Reflex, Stretch / Q000502:physiology*