Results of a pilot study on the involvement of bilateral inferior frontal gyri in emotional prosody perception: an rTMS study

<p>Abstract</p> <p>Background</p> <p>The 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.</p> <p>Results</p> <p>Reaction 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.</p> <p>Conclusions</p> <p>The 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.</p

Time Course of the Involvement of the Right Anterior Superior Temporal Gyrus and the Right Fronto-Parietal Operculum in Emotional Prosody Perception

In verbal communication, not only the meaning of the words convey information, but also the tone of voice (prosody) conveys crucial information about the emotional state and intentions of others. In various studies right frontal and right temporal regions have been found to play a role in emotional prosody perception. Here, we used triple-pulse repetitive transcranial magnetic stimulation (rTMS) to shed light on the precise time course of involvement of the right anterior superior temporal gyrus and the right fronto-parietal operculum. We hypothesized that information would be processed in the right anterior superior temporal gyrus before being processed in the right fronto-parietal operculum. Right-handed healthy subjects performed an emotional prosody task. During listening to each sentence a triplet of TMS pulses was applied to one of the regions at one of six time points (400–1900 ms). Results showed a significant main effect of Time for right anterior superior temporal gyrus and right fronto-parietal operculum. The largest interference was observed half-way through the sentence. This effect was stronger for withdrawal emotions than for the approach emotion. A further experiment with the inclusion of an active control condition, TMS over the EEG site POz (midline parietal-occipital junction), revealed stronger effects at the fronto-parietal operculum and anterior superior temporal gyrus relative to the active control condition. No evidence was found for sequential processing of emotional prosodic information from right anterior superior temporal gyrus to the right fronto-parietal operculum, but the results revealed more parallel processing. Our results suggest that both right fronto-parietal operculum and right anterior superior temporal gyrus are critical for emotional prosody perception at a relatively late time period after sentence onset. This may reflect that emotional cues can still be ambiguous at the beginning of sentences, but become more apparent half-way through the sentence

Impaired recognition and expression of emotional prosody in schizophrenia: Review and meta-analysis

Background: Deficits in emotion processing may be one of the most pervasive disturbances in schizophrenia that may contribute to social isolation. In this report we focus on vocal emotion processing. This function bears upon two corner stones of social functioning, language and emotion, which have both been found to be impaired in schizophrenia. Methods: We used meta-analysis to integrate findings of studies published between 1980 and June 2007 on perception of emotional prosody in schizophrenia. 17 studies provided sufficient information to be included. A mean weighted effect size was computed in the random effects model. Publication bias was tested using funnel plots and fail-safe number of studies. Seven studies were included in an analysis on the expression (i.e. production) of emotional prosody in schizophrenia. Results: A significant and stable mean weighted effect size was found for the perception of emotional prosody, d=-1.24, 95% CI=-1.55 to -0.93. The effect was also found in the early stages of the illness. Expression of emotional prosody was also significantly impaired, d=-1.11, 95% CI=-1.78 to -0.43. Conclusions: Results indicate that individuals with schizophrenia are impaired in the perception and expression of emotional prosody, with a large effect size. As a growing body of evidence shows that impaired social cognition in schizophrenia may be an important predictor of social outcome, training programs that aim at the recognition of emotional prosody should be developed. (C) 2007 Elsevier B.V. All rights reserved

Emotion identified correctly (%) during triple-pulse rTMS for the three conditions

<p>No significant differences were found on percentages correct between the three sites, fronto-parietal operculum (FPO), anterior superior temporal gyrus (aSTG) and POz (EEG electrode site).</p

This figure shows the two TMS locations that are targeted in the present study drawn in MRIcro, the fronto-parietal operculum and the anterior superior temporal gyrus.

<p>This figure shows the two TMS locations that are targeted in the present study drawn in MRIcro, the fronto-parietal operculum and the anterior superior temporal gyrus.</p

Reaction times on emotional prosody task during triple-pulse rTMS at different time-point at the right anterior superior temporal gyrus (aSTG, n = 14 subjects), the fronto-parietal operculum (FPO, n = 14 subjects) and at the POz-EEG location (n = 10 subjects) for detection of emotional intonations.

<p>A: reaction times for perception of fearful intonations, B: reaction times for perception of sad intonations and C: reaction times for detection of happy intonations.</p

Reaction times during triple-pulse rTMS for the three conditions

<p>No significant differences were observed between fronto-parietal operculum (FPO) and anterior superior temporal gyrus (aSTG) with regard to reaction times. Reaction times on POz were significantly different from both FPO and aSTG. Reaction times after triple-pulse rTMS at 1300ms after onset of the sentence were significantly higher than at all other time-points.</p