Temporal dynamics of amygdala and orbitofrontal responses to emotional prosody using intracerebral local field potentials in humans

A. Christen and D. Grandjean, University of Geneva

The purpose of this study was to investigate how emotional prosody can modulate brain responses, taken into account the temporal dynamic of this process as a key characteristic. This study involves a young woman suffering from chronic and pharmaco-resistant epilepsy as a potential candidate to brain surgery. We used a dichotic listening paradigm, in which two neutral and/or angry pseudo-words were presented simultaneously on both ears. The task, orthogonal to emotional prosody, required the patient to identify the gender of the speaker on the side where her attention was directed. By using deep brain electrodes in order to record local field potentials (LFP), intracranial evoked potentials were computed in three brain areas: the right and left amygdala, as well as the right orbitofrontal cortex. We hypothesized that angry prosody would increase both early and late brain responses compared to neutral prosody. As expected, our results show that neuronal responses to angry prosody were enhanced early in the amygdala as well as later in the orbitofrontal cortex, compared to neutral prosody. These results are compatible with an early amygdala response to emotional prosody and a later neuronal modulation within the orbitofrontal cortex, highlighting a possible functional connectivity between these two key structures in the processing of emotional prosody.