Brain mapping of emotional prosody in patients with drug-resistant temporal epilepsy: An indicator of plasticity.

INTRODUCTION: Emotional prosody, a suprasegmental component of language, is predominantly processed by right temporo-frontal areas of the cerebral cortex. In temporal lobe epilepsy (TLE), brain disturbances affecting prosody processing frequently occur. This research assesses compensatory brain mechanisms of prosody processing in refractory TLE using fMRI. METHODS: Patients with focal unilateral epilepsy, right (RTLE) (N = 19), left (LTLE) (N = 19), and healthy controls (CTRL) (N = 20) were evaluated during a prosody decoding fMRI task. The stimuli consisted in spoken numbers with different tones of voice (joy, fear, anger, neutral and silent trials). Participants were instructed to label the emotion with a keypad. "Joy" was removed from the analysis due to a high degree of variability. A lateralization index (LI) was used to see individual differences in the interhemispheric activations of each participant. RESULTS: Behaviorally, The LTLE and RTLE groups did not differ significantly from each other neither from CTRL. In Negative Emotions versus Baseline contrast, the whole sample analysis showed extensive activations in bilateral superior temporal gyrus, bilateral precentral and post-central gyrus, right putamen, and left cerebellar vermis. Compared to the LTLE and CTRL, RTLE activated similar areas, but to a lesser extent. The LI analysis revealed significant differences in hemispheric laterality of the temporal lobe and the parietal lobe between RTLE compared to LTLE and CTRL, being the RTLE group lateralized towards the left, unlike the other two groups. DISCUSSION: The LI indicated that, since the CTRL and the LTLE groups recruited putative prosodic regions, the RTLE lateralized prosody processing towards the left, recruiting contralateral nodes, homotopic to the putative areas of the prosody. Considering that the groups did not differ in prosody task performance, the findings suggest that, in the RTLE group, alternative brain nodes were recruited for the task, demonstrating plasticity.

Emotional salience enhances intelligibility in adverse acoustic conditions.

INTRODUCTION: Emotion facilitates word recognition under adverse acoustic conditions. We use an auditory emotional paradigm to evaluate the ability to distinguish words from irrelevant random stimuli, elucidating its neural correlates. Secondarily, we evaluate the impact of schizotypy traits on this capacity. METHODS: 25 participants, undertook an fMRI task, indicating whether they recognized words, through a response box. 20 audio files of emotionally negative words and 20 neutral words were presented. Word intelligibility was manipulated merging the audio files with white noise at varying signal-to-noise ratios (SNR), resulting in 3 levels (high, medium, and low). We measured schizotypy with the O-LIFE scale. RESULTS: A 2x3 factorial ANOVA was performed with emotion (neutral or negative) and intelligibility (high, medium, and low) as factors. There was an interaction between emotion and intelligibility [F(2,44) = 23.89,p<0.001]. Post hoc t-test demonstrated that, in medium and low intelligibility, negative words were more recognized than neutral ones. Negative words minus neutral, activated the right anterior cingulate cortex (rACC), right dorsolateral prefrontal cortex (rDLPFC), and right orbitofrontal cortex (rOFC). Low compared to high intelligibility, activated the left medial temporal gyrus (lMTG), left supramarginal gyrus (lSMG), and left angular gyrus (lAG). Medium compared with high intelligibility, activated the left temporal pole (lTP) and the lMTG. There were correlations between schizotypy and rACC, lMTG, and rOFC activations. DISCUSSION: Negative emotional salience improves intelligibility, possibly by recruiting selective attention. Less intelligible stimuli activated temporo-parietal regions related to speech processing in adverse acoustic conditions, while emotionally negative stimuli activated areas associated with emotional processing (rACC and rOFC) and selective attention (rDLPFC). High schizotypy correlated with greater responses in rACC, lMTG, and rOFC, during low intelligibility. Irrelevant emotionally salient stimuli would capture automatic attention activating rACC and rOFC, enhancing speech comprehension through additional recruitment of lMTG, which could derive in false word recognition.