Annett Schirmer

Beyond the right hemisphere: Brain mechanisms mediating vocal emotional processing

Vocal perception is particularly important for understanding a speakers emotional state and intentions because, unlike facial perception, it is relatively independent of speaker distance and viewing conditions. The idea, derived from brain lesion studies, that vocal emotional comprehension is a special domain of the right hemisphere has failed to receive consistent support from neuroimaging. This conflict can be reconciled if vocal emotional comprehension is viewed as a multi-step process with individual neural representations. This view reveals a processing chain that proceeds from the ventral auditory pathway to brain structures implicated in cognition and emotion. Thus, vocal emotional comprehension appears to be mediated by bilateral mechanisms anchored within sensory, cognitive and emotional processing systems.

Sex differentiates the role of emotional prosody during word processing

The meaning of a speech stream is communicated by more than the particular words used by the speaker. For example, speech melody, referred to as prosody, also contributes to meaning. In a cross-modal priming study we investigated the influence of emotional prosody on the processing of visually presented positive and negative target words. The results indicate that emotional prosody modulates word processing and that the time-course of this modulation differs for males and females. Women show behavioural and electrophysiological priming effects already with a small interval between the prosodic prime and the visual target word. In men, however, similar effects of emotional prosody on word processing occur only for a longer interval between prime and target. This indicates that women make an earlier use of emotional prosody during word processing as compared to men.

ERP Evidence for a Sex-Specific Stroop Effect in Emotional Speech

The present study investigated the interaction of emotional prosody and word valence during emotional comprehension in men and women. In a prosody-word interference task, participants listened to positive, neutral, and negative words that were spoken with a happy, neutral, and angry prosody. Participants were asked to rate word valence while ignoring emotional prosody, or vice versa. Congruent stimuli were responded faster and more accurately as compared to incongruent emotional stimuli. This behavioral effect was more salient for the word valence task than for the prosodic task and was comparable between men and women. The event-related potentials (ERPs) revealed a smaller N400 amplitude for congruent as compared to emotionally incongruent stimuli. This ERP effect, however, was significant only for the word valence judgment and only for female listeners. The present data suggest that the word valence judgment was more difficult and more easily influenced by task-irrelevant emotional information than the prosodic task in both men and women. Furthermore, although emotional prosody and word valence may have a similar influence on an emotional judgment in both sexes, ERPs indicate sex differences in the underlying processing. Women, but not men, show an interaction between prosody and word valence during a semantic processing stage.

Brain Responses to Segmentally and Tonally Induced Semantic Violations in Cantonese

The present event-related potential (ERP) study examined the role of tone and segmental information in Cantonese word processing. To this end, participants listened to sentences that were either semantically correct or contained a semantically incorrect word. Semantically incorrect words differed from the most expected sentence completion at the tone level, at the segmental level, or at both levels. All semantically incorrect words elicited an increased frontal negativity that was maximal 300 msec following word onset and an increased centroparietal positivity that was maximal 650 msec following word onset. There were differences between completely incongruous words and the other two violation conditions with respect to the latency and amplitude of the ERP effects. These differences may be due to differences in the onset of acoustic deviation of the presented from the expected word and different mechanisms involved in the processing of complete as compared to partial acoustic deviations. Most importantly, however, tonally and segmentally induced semantic violations were comparable. This suggests that listeners access tone and segmental information at a similar point in time and that both types of information play comparable roles during word processing in Cantonese.

Gender differences in the activation of inferior frontal cortex during emotional speech perception

We investigated the brain regions that mediate the processing of emotional speech in men and women by presenting positive and negative words that were spoken with happy or angry prosody. Hence, emotional prosody and word valence were either congruous or incongruous. We assumed that an fRMI contrast between congruous and incongruous presentations would reveal the structures that mediate the interaction of emotional prosody and word valence. The left inferior frontal gyrus (IFG) was more strongly activated in incongruous as compared to congruous trials. This difference in IFG activity was significantly larger in women than in men. Moreover, the congruence effect was significant in women whereas it only appeared as a tendency in men. As the left IFG has been repeatedly implicated in semantic processing, these findings are taken as evidence that semantic processing in women is more susceptible to influences from emotional prosody than is semantic processing in men. Moreover, the present data suggest that the left IFG mediates increased semantic processing demands imposed by an incongruence between emotional prosody and word valence.

Lateralization of prosody during language production: A lesion study

To examine brain lateralization of prosody during speech, the sentence production of six right-hemisphere-lesion patients and five left-hemisphere-lesion patients was compared to that of seven normal controls using a question-answer paradigm. The task required the prosodic realization of two different syntactic structures under conditions of wide and narrow focus. Acoustical analyses were carried out on F0 and time structure. These analyses revealed a preserved ability in patients to express differences in syntactic structure via prosody. However, there were deficits in distinguishing narrow focus from wide focus. Whereas both right- and left-hemisphere lesions caused impairments in the realization of F0, time structure was mainly impaired in left-hemisphere patients. Therefore, the present results from language production support functional as well as cue-dependent hypotheses of the lateralization of prosodic processing in the brain.

Variability of Affective Responses to Odors: Culture, Gender, and Olfactory Knowledge

Emotion and odor scales (EOS) measuring odor-related affective feelings were recently developed for three different countries (Switzerland, United Kingdom, and Singapore). The first aim of this study was to investigate gender and cultural differences in verbal affective response to odors, measured with EOS and the usual pleasantness scale. To better understand this variability, the second aim was to investigate the link between affective reports and olfactory knowledge (familiarity and identification). Responses of 772 participants smelling 56-59 odors were collected in the three countries. Women rated odors as more intense and identified them better in all countries, but no reliable sex differences were found for verbal affective responses to odors. Disgust-related feelings revealed odor-dependent sex differences, due to sex differences in identification and categorization. Further, increased odor knowledge was related to more positive affects as reported with pleasantness and odor-related feeling evaluations, which can be related to top-down influences on odor representation. These top-down influences were thought, for example, to relate to beliefs about odor properties or to categorization (edible vs. nonedible). Finally, the link between odor knowledge and olfactory affect was generally asymmetrical and significant only for pleasant odors, not for unpleasant ones that seemed to be more resistant to cognitive influences. This study, for the first time using emotional scales that are appropriate to the olfactory domain, brings new insights into the variability of affective responses to odors and its relationship to odor knowledge.

Affective Dimensions of Odor Perception: A Comparison Between Swiss, British, and Singaporean Populations

Do affective responses to odors vary as a function of culture? To address this question, we developed two self-report scales in the United Kingdom (Liverpool: LEOS) and in Singapore (city of Singapore: SEOS), following the same procedure as used in the past to develop the Geneva Emotion and Odor Scale (GEOS: Chrea, Grandjean, Delplanque et al., 2009). The final scales were obtained by a three-step reduction of an initial pool of 480 affective terms, retaining only the most relevant terms to describe odor-related subjective affective states and comprised of six (GEOS) or seven affective dimensions (LEOS and SEOS). These included dimensions that were common to the three cultures (Disgust, Happiness Well-being, Sensuality Desire, and Energy), common to the two European samples (Soothing Peacefulness), and dimensions that were culture specific (Sensory Pleasure in Geneva; Nostalgia and Hunger Thirst in Liverpool; Intellectual Stimulation, Spirituality, and Negative Feelings in Singapore). A comparative approach showed that the dimensional organization of odor-related affective terms in a given culture better explained data variability for that culture than data variability for the other cultures, thus highlighting the importance of culture-specific tools in the investigation of odor-related affect.

Unattended musical beats enhance visual processing

The present study investigated whether and how a musical rhythm entrains a listeners visual attention. To this end, participants were presented with pictures of faces and houses and indicated whether picture orientation was upright or inverted. Participants performed this task in silence or with a musical rhythm playing in the background. In the latter condition, pictures could occur off-beat or on a rhythmically implied, silent beat. Pictures presented without the musical rhythm and off-beat were responded to more slowly than pictures presented on-beat. This effect was comparable for faces and houses. Together these results indicate that musical rhythm both synchronizes and facilitates concurrent stimulus processing.

On the spatial organization of sound processing in the human temporal lobe: A meta-analysis

In analogy to visual object recognition, proposals have been made that auditory object recognition is organized by sound class (e.g., vocal/non-vocal, linguistic/non-linguistic) and linked to several pathways or processing streams with specific functions. To test these proposals, we analyzed temporal lobe activations from 297 neuroimaging studies on vocal, musical and environmental sound processing. We found that all sound classes elicited activations anteriorly, posteriorly and ventrally of primary auditory cortex. However, rather than being sound class (e.g., voice) or attribute (e.g., complexity) specific, these processing streams correlated with sound knowledge or experience. Specifically, an anterior stream seemed to support general, sound class independent sound recognition and discourse-level semantic processing. A posterior stream could be best explained as supporting the embodiment of sound associated actions and a ventral stream as supporting multimodal conceptual representations. Vocalizations and music engaged these streams evenly in the left and right hemispheres, whereas environmental sounds produced a left-lateralized pattern. Together, these results both challenge and confirm existing proposal of temporal lobe specialization. Moreover, they suggest that the temporal lobe maintains the neuroanatomical building blocks for an all-purpose sound comprehension system that, instead of being preset for a particular sound class, is shaped in interaction with an individuals sonic environment.