Figure 6 Localization of cerebral activity during singing. Peaks of CBF during repetitive singing of a single pitch on the vowel /a/ at a rate of about 1250 msec as measured with PET. Saggital (A-D) and coronal (E and F) slices from the mean CBF change t-statistic volume superimposed on the averaged MRI in Taillarach coordinates from a group of 13 nonmusician subjects. In critical regions, the same rCBF data are shown superimposed on an individual MRI in order to view their relationship to sulci not clearly visible in the group average. The dotted rectangles in slices A, B, and E correspond to the regions depicted in the individual MRI offset to the right. Peaks were observed as follows: (A) in the first long gyrus (precentral) of the insula, also critical for motor speech; (B) (from top to bottom) the supplementary motor area, anterior cingulate sulcus (note the marginal ramus of the cingulate sulcus; arrowhead), visual cortex activation that is part of a right lingual peak, and cerebellar activation coextensive with more lateral peaks; (C) relatively dorsal left central sulcus (note the position of the central sulcus at the dorsal edge of the slice and in the more medial slice A) (also visible is the lateral extension of the insular peak seen in A); (D) dorsal and ventral right central sulcus—the activated voxels just below the Sylvian fissure extend from the more medial peak in Heschl's gyrus; (E) right Heschl's gyrus (position indicated by the arrowhead and more clearly visible on the individual MRI), dorsal left central sulcus (seen also in C), and ventral right central sulcus (also seen in D); (F) right superior temporal plane (STP) and the overlying right parietal operculum and the left parietal operculum (reproduced with permission from Perry et al., 1999).

control have been studied for many years (e.g., the work of Otto Ortmann on piano performance), study of the cortical control required in specifically musical contexts is sparse. A few studies have utilized computer-interfaced piano keyboards to study piano performance by musicians, the cortical control of sequential finger movements in nonmusicians, or the production of rhythms using a single computer key as if it were a piano key. The simplest sequences studied were repetitive, isochronous presses of a single key. In contrast to the vocal studies mentioned previously, in several of these studies no sound was produced. Although the behaviors are thus not fully musical, they allow separation of motor control from the auditory-motor integrative aspects.

Penhune and Zatorre measured CBF increases during the reproduction of an isochronous sequence (cued either visually or auditorily) on a single computer key using the right hand, in contrast to perception of the cue alone. Common areas of activation were seen in the contralateral somatomotor cortex, basal ganglia, and ipsilateral cerebellum. Activation in the SMA was also seen, but only for the auditorily cued condition. In a similar auditorily cued task, Stephen Rao and colleagues used functional MRI to examine CBF as subjects continued tapping a key at a fixed rate with the right hand. Increases were seen in the same areas: contralateral somatomotor cortex, basal ganglia, ipsilateral cerebellum, and SMA.

These studies illustrate the cortical areas involved in the control of manual motor output in a quasi-musical context, consistent with what would be expected for timed manual movements in general. These areas are similar to those seen during isochronous, isofrequency vocal motor output, except that processing of auditory feedback is excluded and somatosensory feedback is emphasized.

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