+ [M.V. Peelen,A.P. Atkinson and P. Vuilleumier The Journal of Neuroscience, July 28, 2010 • 30(30):10127–10134 ] SUPRAMODAL REPRESENTATIONS OF PERCEIVED EMOTIONS IN THE HUMAN BRAINMONDAY 27 FEBRUARY 2012 MSCs: Angelo Bruschi, MD
+ INTRODUCTION (I) Successful social interaction requires a precise understanding of the feelings, thoughts, intentions and desires of other people. Humans have the exceptional ability to infer complex mental states from subtle sensory cues. (e.g. Face, Body, Voice). (de Gelder et al., 2006 ) These signals lead to the recognition of an emotional state and activate similar emotion-specific responses in the observer. (Magnée et al., 2007)
+ MAIN QUESTION (II) ARE THERE ANY BRAIN REGIONS THAT ENCODE EMOTIONS INDIPENDENTLY OF THE MODALITY THROUGH WICH THEY ARE PERCEIVED?
+ STUDY DESIGN (III) VOICE STIMULI HEALTY fMRI BODY VOLUNTEERS RESPONSES EMOTIONS FACIAL EMOTIONS
+ PARTICIPANTS(IV) 18 Adult Healthy Volunteers (10 women, mean age 26, range 20-32) HAPPINESS ANGER All right handed, normal vision, no history SADNESS of psychiatric or neurological disease FEAR DISGUST 5 different emotions chosen
+ EMOTIONAL STIMULI: FACES (V) Movies of emotional faces expression taken from Banse and Scherer (1996). Non facial body parts were cropped. 5 different emotions chosen (Anger, Disgust, Happiness, Fear, Sadness). Four actors (2 male + 2 female) expressed each emotion.
+ EMOTIONAL STIMULI: BODY (VI) Movies of emotional body expression taken from Atkinson (2004). Actors wore uniform dark-grey, tight-fitting clothes and headwear so that all body parts (including face) were covered. 5 different emotions chosen (Anger, Disgust, Happiness, Fear, Sadness). Four actors (2 male + 2 female) expressed each emotion.
+ EMOTIONAL STIMULI: VOICE (VII) Emotional voice stimuli taken from Montreal Affective Voice set, Belin(2008). Consisted of short (~1s), non linguistic interjections (“Ahh”) expressing different emotions. 5 different emotions chosen (Anger, Disgust, Happiness, Fear, Sadness) Four actors (2 male + 2 female) expressed each emotion
+ DESIGN AND PROCEDURE (VIII) Participants performed 6 fMRI runs, each of 36 trials as shown in figure. 3 blocks of 12 trials, differing in type of stimuli, with 2 different clips for each of the 5 emotions. Trials presented in random order, to prevent any prediction bias. After each presentation, participants rated each stimulus on a 3 point scale. (Enhancement of involved brain regions)
+ DATA ACQUISITION: fMRI (IX) fMRI data were analysed using Multivoxel Pattern Analysis (MVPA): a technique sensitive to fine-grained neural representations. (Haynes & Rees, 2005) Moreover, using a spherical searchlight approach they tested for regions in the brain where local activity patterns contained information about emotion categories (fear, anger, etc.) independent of stimulus modality (body, voice, face). (Kriegeskorte et al., 2006)
+ RESULTS: BEHAVIOURAL (X) The average rating of the perceived emotions is 2,24 (as show in figure) Differences between perceived intensities of emotions depended on modality (p< 0.001). (Anger > Voice Disgust > Body) THEY EXCLUDED THE POSSIBILITY THAT DIFFERENCES IN PERCEIVED INTENSITY COULD PROVIDE AN ALTERNATIVE EXPLANATION FOR SUPRAMODAL EMOTION-SPECIFIC fMRI RESPONSES. (NONE OF THE CORRELATIONS POSITIVE)
+ RESULTS: fMRI (XI) TWO CLUSTERS SHOWED SUPRAMODAL EMOTION INFORMATION: rmPFC and left STS Results of a whole-brain searchlight analysis showed clusters with significant emotion-specific activity patterns across modality. Similarity of activity patterns was expressed as a correlation value, with higher correlations indicating higher similarity. rmPFC (p<0.05) and left STS (p<0.00001) Similarity of activity patterns was expressed as a correlation value, with higher correlations indicating higher similarity.
+ RESULTS: fMRI (XII) SUPPLEMENTAL MATERIAL Supp Figure 1. Graphs showing the correlation matrices between the 5 emotion categories, averaged across the 3 cross‐modality comparisons (face‐body, face‐ Graphs showing the correlation matrices between the 5 emotion categories, averaged voice, body‐voice) in MPFC (left) and STS (right) searchlight clusters. These across the 3 cross-modality comparisons. These matrices provide information about the matrices provide information about the similarities between the emotion‐related similarities patterns. In both regions, the average within‐emotion correlation was fMRI activity between the emotion-related fMRI activity patterns. significantly higher than the average between‐emotion correlation (see Figure 3, main text). In MPFC, the within‐emotion correlations (diagonal elements) were The activity associate with the between‐emotion correlations for Fear, different stimulus types higher than each of the 4 corresponding same emotion perceived from Disgust, and Happiness. Anger was equally correlated with Anger (r=0.5), Disgust (Diagonal Elements) more Sadness was relatively highly correlated with than between them: (r=0.5), and Fear (r=0.5), whereas similar within emotion categories Disgust and Anger. In STS, all within‐emotion correlations were higher than each of the 4 corresponding between‐emotion correlations. Note that different scales were used for MPFC (0.35‐0.55) and STS (0.55‐0.75) PERCEIVED EMOTIONS THERE IS A SUPRAMODAL REPRESENTATION OF graphs, reflecting the difference in the mean correlation of these regions (see also Figure 3, main text). Abbreviations: Ang=anger, Dis=disgust, Fea=fear, Hap=happiness, Sad=sadness.
+ DISCUSSION: SUMMARY (XIII) Multi Voxel Pattern of activity in two cortical brain regions (rmPFC and left STS) carried information about emotion categories REGARDLESS of the specific sensory cues (Body, Face and Voice stimuli). NO DIFFERENCES FOUNDED between the perceived intensity of different emotion categories: EMOTION SPECIFIC PATTERNS in rmPFC and STS could be related to SYSTEMATIC DIFFERENCES in the intensity of different emotions. NO CONSISTENT DIFFERENCES between emotion categories in the average magnitude of activity of these regions, indicating SIMILAR OVERALL RECRUITMENT of rmPFC and STS in processing different types of emotions
+ DISCUSSION: HYPOTESIS 1 (XIV) BRIEFLY , THESE AREAS PROCESS THE "CONTENT" OF A STIMULUS, REGARDLESS OF ITS SENSORY CHARACTERISTICS. FIRST HYPOTESIS: These regions contains individual neurons that selectively represent emotion categories at an ABSTRACT LEVEL. It is not known if this specific tuning may be limited to the basic emotion categories used here or it’s possible to extend to: THE BASIC EMOTION USED IN THIS STUDY (Oatley & Johnson-Laird, 1987) OTHER EMOTIONS (eg. Guilt, Shame) (Binder et al., 2009) NON EMOTIONAL MENTAL STATES (Binder et al., 2009) CONCEPTUAL REPRESENTATION MORE GENERALLY (Binder et al., 2009)
+ DISCUSSION: HYPOTESIS 2 (XV) BRIEFLY , THESE AREAS PROCESS THE "CONTENT" OF A STIMULUS, REGARDLESS OF ITS SENSORY CHARACTERISTICS. SECOND HYPOTESIS: It is possible that Neurons in rmPCF and/or left STS may code for: PARTICULAR EMOTION DIMENSIONS (Russel, 1980) SPECIFIC EMOTION COMPONENTS (Novelty, Pleasantness, Relevance) (Scherer, 1984) ACTION TENDENCIES ASSOCIATED WITH EMOTIONS (Frijda, 1987)
+ CONCLUSIONS: FUTURE STUDIES (XV) QUESTIONS FOR FUTURE STUDIES: RMPFC AND STS REPRESENT OTHER (EMOTIONAL AND NON EMOTIONAL) MENTAL STATES THAN THOSE TESTED? WHAT EXTENT IS EMOTION SPECIFICITY IN THESE AREAS RELATED TO THE EXPLICIT EVALUATION OF THE EMOTIONS? DOES EMOTION SPECIFICITY PERSIST WHEN STIMULI IS PRESENTED OUTSIDE THE FOCUS OF ATTENTION? ARE RMPFC AND STS SIMILARLY ACTIVATED BY PERCEIVED AND EXPERIENCED EMOTIONS? IS THERE AN OVERLAP IN THE REPRESENTATION OF PERCEIVED EMOTIONS AND SELF EXPERIENCED?