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Abstract:
Abstract: Auditory processing in the primate cortex is
postulated to proceed along a "sound localization" and a "sound
pattern" processing stream (Rauschecker et al., 1998). We examined
the neural localization for processing three functionally distinct
types of sound patterns, namely speech, music and environmental
sounds using the BOLD method of fMRI in six right-handed human
males. Nineteen contiguous axial T2* weighted gradient-echo EPI
images were obtained using a 1.5T Magnetom Siemens Vision Imager.
Activation was visualized at a significance level of 0.01 for sound
presentation versus silence (background noise). T1-weighted 3D
volumes were acquired for anatomical localization. Speech sounds
produced clustered activation in the supra and middle temporal
gyrus, and a single focus of activation in the central sulcus and
middle frontal gyrus, predominantly in the left hemisphere, whereas
musical melodies activated some of the same areas, predominantly in
the right hemisphere. Music also produced some activation in the
auditory cortex on the right side. Nonspeech environmental sounds
produced mostly bilateral activation in the auditory cortex as well
as at the level of the pre- and post-central gyri. These results
indicate that processing of different types of complex sound
patterns in humans is parceled within distributed and largely
separate networks at and beyond the level of the auditory
cortex.
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