The role of the anterior cingulate cortex in pitch variation during sad affect

We examined neural activity, in the frontal lobes, associated with speech production during affective states. Using functional magnetic resonance imaging (fMRI), the blood oxygen level-dependent (BOLD) response to the overt reading of emotionally neutral sentences was measured before and after a happy or sad mood induction. There was no explicit demand to produce affect-congruent speech and a cover story was used to de-emphasize the significance of the speech task in light of our experimental aims. Each fMRI measurement was acquired 6 s after the onset of sentence presentation so that speech could be recorded while the scanner noise was minimal; speech parameters (e.g. pitch variation) were extracted from the sentences and regressed against fMRI data. In the sad group we found the predicted changes in affect and pitch variation. Further, the fMRI data confirmed our hypothesis in that the 'reading effect' (i.e. the BOLD response to reading minus the BOLD response to baseline stimuli) in the supracallosal anterior cingulate cortex covaried negatively with both pitch variation and affect. Our results suggest that the anterior cingulate cortex modulates paralinguistic features of speech during affective states, thus placing this neural structure at the interface between action and emotions.