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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
TRIPLE
Enrollment
48
The effects of over-the-counter nicotine gum will be compared to a placebo gum
The effects of over-the-counter nicotine gum will be compared to a placebo gum
University of California, Berkeley
Berkeley, California, United States
RECRUITINGfrequency tuning of excitatory auditory fMRI cortical responses
Functional magnetic resonance imaging (fMRI) responses to pure tone stimuli ranging from 88-8000 Hz will be recorded. For each voxel in objectively identified auditory cortical area, a tuning curve model will be fit to the data. One of the parameters of this model is the width of frequency tuning of excitatory responses, and this is the primary outcome measure.
Time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of polacrilex or placebo gum and will continue for up to two hours.
frequency tuning of inhibitory auditory fMRI cortical responses
Functional magnetic resonance imaging (fMRI) responses to pure tone stimuli ranging from 88-8000 Hz will be recorded. For each voxel in objectively identified auditory cortical area, a tuning curve model will be fit to the data. One of the parameters of this model is the width of frequency tuning of inhibitory responses, and this is Outcome 2.
Time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of polacrilex or placebo gum and will continue for up to two hours.
amplitude of excitatory auditory fMRI cortical responses
Functional magnetic resonance imaging (fMRI) responses to pure tone stimuli ranging from 88-8000 Hz will be recorded. For each voxel in objectively identified auditory cortical area, a tuning curve model will be fit to the data. One of the parameters of this model is the amplitude of excitatory responses, and this is Outcome 3.
Time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of polacrilex or placebo gum and will continue for up to two hours.
amplitude of inhibitory auditory fMRI cortical responses
Functional magnetic resonance imaging (fMRI) responses to pure tone stimuli ranging from 88-8000 Hz will be recorded. For each voxel in objectively identified auditory cortical area, a tuning curve model will be fit to the data. One of the parameters of this model is the amplitude of inhibitory responses, and this is Outcome 4.
Time frame: Functional MRI recordings will begin approximately 30 minutes after oral administration of polacrilex or placebo gum and will continue for up to two hours.
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