A total of 12 subjects participated in these experiments. They ranged in age from 19 to 35. Ten of the subjects were male. Nine were right-handed. Subjects had no known audiological or neurological disorders. The experiments consisted of the following elements:
Experiments I and II (Noise burst trains with different repetition rates): Nine subjects participated in a total of 11 imaging sessions for experiments I and II. The stimuli were bursts of uniformly distributed white noise. Individual noise bursts in all four experiments were 25 minutes (ms) in duration (full-width half-maximum), with a rise/fall time of 2.5 ms. The bursts were presented at repetition rates of 1, 2, 10, and 35/s (experiment I) or 2, 10, 20, and 35/s (experiment II). The 1/s rate was used in only three of the five sessions of experiment I. The spectrum of the noise stimulus at the subjects' ears was low-pass, reflecting the frequency response of the acoustic system. Noise bursts were presented in 30-s trains alternated with 30-s "off" periods, during which no auditory stimulus was presented.
Experiment III (Small numbers of noise bursts): To investigate how the initial bursts of a train contribute to cortical responses to the onset of a train, the researchers examined the responses to a single noise burst and short clusters of noise bursts. Responses were collected in three imaging sessions with three subjects. Either one noise burst or a cluster of noise bursts was presented once every 18 s, constituting a single "trial".
Experiment IV (Noise burst trains with different durations): The effect of train duration was examined in two imaging sessions with two subjects. Trains of four different du
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Contact: Donna Krupa
djkrupa1@aol.com
703-527-7357
American Physiological Society
12-Nov-2002