Abstract:
Cerebral metabolic responses to verbal and nonverbal auditory
stimuli were examined, using 18F-fluorodeoxyglucose and positron CT.
Twenty right-handed subjects were studied in both control and stimulated
states. Monaural verbal stimuli produced diffuse metabolic changes in
the left hemisphere and bilateral activation of the transverse and
posterior temporal lobes. Monaural nonverbal stimulation with chords
demonstrated bilateral parietotemporal activations and diffuse right
greater than left frontotemporal asymmetries. Tone sequence pairs
presented monaurally produced asymmetries that differed by the
subject's analysis strategy. Nonanalytical, musically naive subjects
had right greater than left frontotemporal asymmetries, whereas analytic
or musically sophisticated subjects had an absence of right greater than
left relative hypermetabolism and demonstrated left greater than right
temporal asymmetries. Binaural presentation of a factual story and music
produced diffuse bilateral activations of the temporal and frontal
cortex. Known anatomic asymmetries of the perisylvian cortex were
revealed by high-resolution tomography. These results demonstrate that
metabolic responses to auditory stimuli are determined by the content of
the stimulus and the analysis strategy of the subject rather than the
side of stimulation. The results also demonstrate the capacity of
functional imaging techniques to study the physiologic cerebral
mechanisms underlying auditory processing