Behavioral and neural aftermath of right inferior frontal cortex disruption on ambiguous vocal emotion decisional processes.

The evaluation of socio-affective auditory information is accomplished by the primary auditory cortex in collaboration with limbic regions and the inferior frontal cortex (IFC)—the latter often recruited during affective voice classification. IFC activity was observed either for coding sensory or perceptual ambiguity or representing more exclusively categorical processes such as object and affect information. Here, we presented ‘clear’ (or ‘pure’) and emotionally ‘ambiguous’ affective speech to two groups of human participants and asked them to explicitly categorize these voices’ emotion. During the task, wholebrain functional magnetic resonance imaging was acquired and combined with transcranial magnetic stimulation, specifically continuous theta-burst stimulation (cTBS; target site: right IFC pars triangularis) between the first and subsequent task runs. Contrary to our hypotheses, offline right IFC disruption through cTBS did not reveal improved accuracy to classify ‘ambiguous’ voices, and instead led to reduced auditory cortical activity and increased fronto-limbic connectivity for ‘clear’ affective speech. Although the expected impact of right IFC cTBS on behavioral performance did not occur, our imaging data still indicate activity patterns modified by the cTBS procedure. This was especially true in the right anterior superior temporal lobe, parietal cortex and superior frontal cortex. Due to the absence of conclusive behavioral results, we discuss our data and study limitations to hopefully allow for clearer design and methods for future work on the important topic of psychological and neural processes underlying vocal emotion decisional processes.