Broca's area and the discrimination of frequency transitions: A functionalMRI study

The left inferior frontal lobe has been traditionally viewed as a "language area," although its involvement in the discrimination of rapid nonverbal f requency changes has been also shown. Using functional MRI, we studied seve n healthy adults during discrimination of relatively slow (200 ms) tonal fr equency glides. Compared to a control task, in which subjects indiscriminat ely responded to white noise bursts, tonal discrimination was associated wi th bilateral superior and middle temporal and medial frontal activations. I nferior frontal activations were bilateral, but stronger on the left. Contr ary to previous studies comparing discrimination of slow frequency changes to rest, our results suggest that such discriminations-when compared to an auditory control task-activate the left inferior frontal gyms. Our findings are consistent with a participation of Broca's area in nonlinguistic proce sses besides its known roles in semantic, syntactic, and phonological funct ions, (C) 2001 Academic Press.