Blunted feelings: alexithymia is associated with a diminished neural response to speech prosody.

How we perceive emotional signals from our environment depends on our personality. Alexithymia, a personality trait characterized by difficulties in emotion regulation has been linked to aberrant brain activity for visual emotional processing. Whether alexithymia also affects the brain's perception of emotional speech prosody is currently unknown. We used functional magnetic resonance imaging to investigate the impact of alexithymia on hemodynamic activity of three a priori regions of the prosody network: the superior temporal gyrus (STG), the inferior frontal gyrus and the amygdala. Twenty-two subjects performed an explicit task (emotional prosody categorization) and an implicit task (metrical stress evaluation) on the same prosodic stimuli. Irrespective of task, alexithymia was associated with a blunted response of the right STG and the bilateral amygdalae to angry, surprised and neutral prosody. Individuals with difficulty describing feelings deactivated the left STG and the bilateral amygdalae to a lesser extent in response to angry compared with neutral prosody, suggesting that they perceived angry prosody as relatively more salient than neutral prosody. In conclusion, alexithymia may be associated with a generally blunted neural response to speech prosody. Such restricted prosodic processing may contribute to problems in social communication associated with this personality trait.

Hearing feelings: a quantitative meta-analysis on the neuroimaging literature of emotional prosody perception.

With the advent of neuroimaging considerable progress has been made in uncovering the neural network involved in the perception of emotional prosody. However, the exact neuroanatomical underpinnings of the emotional prosody perception process remain unclear. Furthermore, it is unclear what the intrahemispheric basis might be of the relative right-hemispheric specialization for emotional prosody perception that has been found previously in the lesion literature. In an attempt to shed light on these issues, quantitative meta-analyses of the neuroimaging literature were performed to investigate which brain areas are robustly associated with stimulus-driven and task-dependent perception of emotional prosody. Also, lateralization analyses were performed to investigate whether statistically reliable hemispheric specialization across studies can be found in these networks. A bilateral temporofrontal network was found to be implicated in emotional prosody perception, generally supporting previously proposed models of emotional prosody perception. Right-lateralized convergence across studies was found in (early) auditory processing areas, suggesting that the right hemispheric specialization for emotional prosody perception reported previously in the lesion literature might be driven by hemispheric specialization for non-prosody-specific fundamental acoustic dimensions of the speech signal.