Pitch underlies activation of the vocal system during affective vocalization

Abstract

Affective prosody is that aspect of speech that conveys a speaker's emotional state through modulations in various vocal parameters, most prominently pitch. While a large body of research implicates the cingulate vocalization area in controlling affective vocalizations in monkeys, no systematic test of functional homology for this area has yet been reported in humans. In this study, we used functional magnetic resonance imaging to compare brain activations when subjects produced affective vocalizations in the form of exclamations vs non-affective vocalizations with similar pitch contours. We also examined the perception of affective vocalizations by having participants make judgments about either the emotions being conveyed by recorded affective vocalizations or the pitch contours of the same vocalizations. Production of affective vocalizations and matched pitch contours activated a highly overlapping set of brain areas, including the larynx-phonation area of the primary motor cortex and a region of the anterior cingulate cortex that is consistent with the macro-anatomical position of the cingulate vocalization area. This overlap contradicts the dominant view that these areas form two distinct vocal pathways with dissociable functions. Instead, we propose that these brain areas are nodes in a single vocal network, with an emphasis on pitch modulation as a vehicle for affective expression.

Keywords: affective prosody; cingulate cortex; fMRI; larynx-phonation area; pitch; voice.

Fig. 1.

Whole brain analyses. (A) Affective vocal production (orange) and pitch-contour vocal production (green) vs rest reveal a remarkable degree of overlap across most of the vocal network, demonstrating little specificity for affective vocalization. (B) Affect perception (orange) and pitch-contour perception (green) vs rest again demonstrate strong overlap between conditions. ACC, anterior cingulate cortex; IFG, inferior frontal gyrus LPA, larynx-phonation area; PAG, periaqueductal gray; SMA, supplementary motor area; STG, superior temporal gyrus; S1, primary somatosensory cortex.

Fig. 2.

Region-of-interest (ROI) analyses. ROIs in the ACC, PAG, LPA and IFG pars orbitalis are indicated by black circles on the axial and midsagittal slices. Mean beta values are plotted for each task and each ROI. Error bars mark one standard error above and below the mean. In each area, there are strong differences between the level of activation for the production and perception tasks, but no difference between the affective and pitch-contour conditions, nor are there any statistical interactions. ACC, anterior cingulate cortex; IFG, inferior frontal gyrus; LPA, larynx-phonation area; PAG, periaqueductal gray.