Functional anatomy of musical processing in listeners with absolute pitch and relative pitch

Abstract

We used both structural and functional brain imaging techniques to investigate the neural basis of absolute pitch (AP), a specialized skill present in some musicians. By using positron emission tomography, we measured cerebral blood flow during the presentation of musical tones to AP possessors and to control musicians without AP. Listening to musical tones resulted in similar patterns of increased cerebral blood flow in auditory cortical areas in both groups, as expected. The AP group also demonstrated activation of the left posterior dorsolateral frontal cortex, an area thought to be related to learning conditional associations. However, a similar pattern of left dorsolateral frontal activity was also observed in non-AP subjects when they made relative pitch judgments of intervals, such as minor or major. Conversely, activity within the right inferior frontal cortex was observed in control but not in AP subjects during the interval-judgment task, suggesting that AP possessors need not access working memory mechanisms in this task. MRI measures of cortical volume indicated a larger left planum temporale in the AP group, which correlated with performance on an pitch-naming task. Our findings suggest that AP may not be associated with a unique pattern of cerebral activity but rather may depend on the recruitment of a specialized network involved in the retrieval and manipulation of verbal-tonal associations.

Figure 1

(A) Waveforms of stimuli used for the noise (baseline) condition. (B) Waveforms for tones used in the activation conditions; note similar amplitude envelope and duration across stimuli. (C) Example of stimulus sequence used, in musical notation, for tones and minor/major conditions.

Figure 2

(Upper) Averaged PET subtraction images are shown superimposed upon the averaged MRI scans for the tones-minus-noise subtraction for listeners with AP (Left) and control musicians—RP (Right). Focal changes in CBF are shown as a t statistic image, values for which are coded by the color scale at the bottom. The two saggital slices, taken at 40 mm to the left of midline, illustrate changes in the midfrontal and parietal regions, common to both groups (Table 2, foci 2 and 6), and a large focal area of CBF increase in the left dorsolateral (DL) frontal cortex (Table 2, focus 1), present only in the AP group (for stereotaxic coordinates and t values for these foci, see Table 2). (Lower) PET/MRI data for the minor/major-minus-noise subtraction for listeners with (Left) and without (Right) AP. The two saggital sections, taken at 37 and 32 mm to the left of midline, illustrate the similar CBF foci in the left DL frontal, midfrontal, and parietal regions for both groups of subjects (Table 3, foci 1, 2, and 8). The two horizontal sections, taken at 13 mm below the bicommisural plane, illustrate the right inferior frontal focus (Table 3, focus 5) present only in the RP group; foci within the middle temporal gyri (MTG) bilaterally are shown in the AP group but were also present, albeit more weakly, in the RP group (Table 3, foci 6 and 7; for stereotaxic coordinates and t values for these foci, see Table 3).