Effects of Nicotine and Attention on Frequency Tuning in Auditory Cortex

Nicotine enhances auditory-cognitive function because it mimics the brain's system for "paying attention" to important sounds amid distractions (for example, understanding speech in a noisy environment). In part, nicotine does this by activating inhibitory neurons in the auditory cortex. Since age-related hearing deficits result, in part, from the loss of inhibitory neurons in auditory cortex, this project will determine whether nicotine's effects can compensate for reduced inhibition in the aging auditory cortex and thereby restore auditory function. The investigators will use functional magnetic resonance imaging (fMRI) to measure the selectivity of responses in auditory cortex to tones of various frequencies. The investigators will measure the effects of nicotine (administered as chewing gum) and aging on these fMRI response properties. The investigators hypothesize that frequency selectivity will decrease with aging and increase following nicotine administration.