Abstract
BackgroundThe right hemisphere may play an important role in paralinguistic features such as the emotional melody in speech. The extent of this involvement however is unclear. Imaging studies have shown involvement of both left and right inferior frontal gyri in emotional prosody perception. The present pilot study examined whether these brain areas are critically involved in the processing of emotional prosody and of semantics in 9 healthy subjects. Repetitive transcranial magnetic stimulation was used with a coil centred over left and right inferior frontal gyri, as localized by neuronavigation based on the subject's MRI. A sham condition was included. An online-TMS approach was applied; an emotional language task was completed during stimulation. This computerized task consisted of sentences pronounced by actors. In the semantics condition an emotion (fear, anger or neutral) was expressed in the content pronounced with a neutral intonation. In the prosody condition the emotion was expressed in the intonation, while the content was neutral.ResultsReaction times on the emotional prosody task condition were significantly longer after rTMS over both the right and the left inferior frontal gyrus as compared to sham stimulation and after controlling for learning effects associated with order of condition. When taking all emotions together, there was no difference in effect on reaction times between the right and left stimulation. For the emotion Fear, reaction times were significantly longer after stimulating the left inferior frontal gyrus as compared to the right inferior frontal gyrus. Reaction times in the semantics task condition were not significantly different between the three TMS conditions.ConclusionsThe data indicate a critical involvement of both the right and the left inferior frontal gyrus in emotional prosody perception. The findings of this pilot study need replication. Future studies should include more subjects and examine whether the left and right inferior frontal gyrus play a differential role and complement each other, e.g. in the integrated processing of linguistic and prosodic aspects of speech, respectively.
Highlights
The right hemisphere may play an important role in paralinguistic features such as the emotional melody in speech
Increased reaction times were observed after 12 min of 1 Hz transcranial magnetic stimulation (TMS) (90% of the motor threshold) over the right fronto-parietal operculum relative to a left-hemisphere sham condition
Mood and speed-accuracy trade off One-factor repeated measures ANOVA, with TMS condition as a factor, revealed that there was no relation between the TMS conditions and the positive and negative affect schedule (PANAS) positive and negative scales
Summary
The right hemisphere may play an important role in paralinguistic features such as the emotional melody in speech. Imaging studies have shown involvement of both left and right inferior frontal gyri in emotional prosody perception. Other imaging studies on emotional prosody perception have shown neural responses in both right and left hemispheres [15,16,17,18,19,20,21,22]. To further define the exact neural substrate of emotional prosody perception and the extent of its lateralization, we used transcranial magnetic stimulation (TMS), a brain mapping technique that allows causal inferences between neural activity and performance at a behavioural level [25,26]. Increased reaction times were observed after 12 min of 1 Hz TMS (90% of the motor threshold) over the right fronto-parietal operculum relative to a left-hemisphere sham condition This effect was specific for emotional prosody discrimination and was not found for discriminating emotional semantics. Detection of withdrawal emotions and not of approach emotions in prosody was delayed significantly by TMS, in accordance with accounts of the neural implementation of approach and withdrawal systems [28]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
