Abstract:

The role of cholinergic mechanisms in the auditory system was investigated by assessing the acute effects of nicotine, a cholinergic drug, on aggregate responses within the auditory pathway. In a single-blind procedure, evoked potentials (auditory brainstem, middle-latency, long-latency, steady-state responses) and electroencephalograms were measured from 20 normal-hearing, nonsmokers (10 male) under two conditions (nicotine, placebo). After the drug session, plasma tests indicated a subject's nicotine concentration. Results indicated that transdermal administration of nicotine to nonsmokers does appear to acutely affect the transmission of acoustic information. The measures most affected by nicotine administration likely originate from the midbrain and cortex and are believed to involve processing of auditory information related to vigilance and the screening of sensory input. The effects of nicotine on evoked potentials or the electroencephalogram do not appear to be dependent on the sex of the subject or the hemisphere from which the responses are measured. [Work supported by AAA and NIDCD.]