Functional asymmetry and interhemispheric cooperation in the perception of emotions from facial expressions

A historical approach to models of emotional laterality

In this paper I discuss the main models that have tried to explain brain asymmetries for emotions. The first models, based on clinical observations, proposed either a general right hemisphere dominance for emotions (the'right hemisphere') model or a different specialization of the right hemisphere for negative and of the left hemisphere for positive emotions (the'valence' model). In more recent times new models, based on partly modified versions of the previous ones have been proposed. The revised version of the 'valence' model, labeled the 'approach-avoidance' model maintained that hemispheric asymmetries are not related to the valence of the emotional stimulus but to the motivational (approach vs avoidance) system that is engaged by that stimulus. On the contrary, revised versions of the 'right hemisphere' hypothesis proposed graded versions of this model, maintaining that only some kinds or some levels of emotions are clearly right lateralized. One version of these models (the'emotion type hypothesis') assumed that only elementary basic emotions should be subsumed by the right hemisphere, wheres more complex social emotions should be subtended by the left hemisphere. The other version (the 'schematic level of emotion hypothesis') assumed that the right hemisphere should subsume only the basic 'schematic' level of emotions, characterized by an automatic and unconscious processing, whereas the more propositional and conscious 'conceptual' level could be less lateralized or subsumed by the left hemisphere. This last model is supported by the obsevation that the right hemisphere reveals a modus operandi (i.e. a prevalence of the 'automatic' over the 'intentional' and of the 'unconscious' over the 'conscious' functional processing) that is typical of the 'schematic level of emotions.

"I cannot see your fear!" Altered recognition of fearful facial expressions in anorexia nervosa

Background

The evidence about facial emotion recognition in anorexia nervosa as the role of alexithymic traits on this emotional ability is conflicting and heterogeneous.

Objective

We assessed the capability of recognizing facial expressions of two primary emotions, fear, and anger, in the context of anorexia nervosa.

Methods

Women affected by anorexia nervosa were compared with healthy weight women in a well-established implicit facial emotion recognition task. Both reaction time and level of accuracy were computed. Moreover, the individual levels of alexithymia were assessed through a standard self-report questionnaire.

Results

Participants with anorexia nervosa reported a significantly lower performance in terms of reaction time and accuracy when the emotion of fear-but not anger-was the target. Notably, such an alteration was linked to the levels of alexithymia reported in the self-report questionnaire.

Conclusion

In anorexia nervosa, difficulties in processing facial fearful (but not angry) expressions may be observed as linked to higher expressions of alexithymic traits. We suggested future research in which emotional processing will be investigated taking into account the role of the bodily dimensions of emotional awareness.

Altered recognition of fearful and angry facial expressions in women with fibromyalgia syndrome: an experimental case-control study

Evidence relative to facial emotion recognition and the role played by alexithymia in fibromyalgia syndrome is rare and heterogeneous. In this work, we investigated this ability in fibromyalgia investigating the implicit behaviour in the facial emotion recognition task, focusing on fear and anger. Twenty women with fibromyalgia and twenty healthy women as controls performed a facial emotion recognition of fearful and angry expressions. Their implicit behaviour was scored in accordance with the redundant target effect. The level of alexithymic traits through a standard psychological questionnaire and its effect on behavioral performance were also assessed. Participants affected by fibromyalgia reported a lower level of accuracy in recognizing fearful and angry expressions, in comparison with the controls. Crucially, such a difference was not explained by the different levels of alexithymic traits between groups. Our results agreed with some previous evidence suggesting an altered recognition of others' emotional facial expressions in fibromyalgia syndrome. Considering the role of emotion recognition on social cognition and psychological well-being in fibromyalgia, we underlined the crucial role of emotional difficulties in the onset and maintenance of the symptoms life-span.

Untrusted under threat: on the superior bond between trustworthiness and threat in face-context integration

The face is a powerful source to make inferences about one's trustworthiness. Recent studies demonstrated that facial trustworthiness is influenced by the level of threat conveyed by the visual scene in which faces are embedded: untrustworthy-looking faces are more likely judged as untrustworthy when shown in threatening scenes. Here, we explore whether this face-context congruency effect is specific to the negative pole of the threat-trust domain. Experiment 1 (N = 89) focused on the differential impact of positive vs. negative face-context congruency within the domains of threat and trust. Negative congruency (i.e. untrustworthy-looking faces in threatening contexts) led to more extreme attributions as opposed to positive congruency (i.e. trustworthy-looking faces in reassuring contexts). Experiment 2 (N = 120) replicated these findings by further showing their domain-specificity. The negativity bias was found in the threat-trust domain, but not when extroverted- vs. introverted-looking faces appeared in happy vs. sad context scenes. Experiment 3 (N = 154, pre-registered) replicated the pattern observed in Experiment 1 while controlling for the extent to which both threatening and reassuring context stimuli were related to the human action. We discussed the theoretical implications of these results for understanding how contextual information is integrated into the evaluation of facial trustworthiness.

Gut Microbiota and Fear Processing in Women Affected by Obesity: An Exploratory Pilot Study

The microbiota–gut–brain axis extends beyond visceral perception, influencing higher-order brain structures, and ultimately psychological functions, such as fear processing. In this exploratory pilot study, we attempted to provide novel experimental evidence of a relationship between gut microbiota composition and diversity, and fear-processing in obesity, through a behavioral approach. Women affected by obesity were enrolled and profiled for gut microbiota, through 16S rRNA amplicon sequencing. Moreover, we tested their ability to recognize facial fearful expressions through an implicit-facial-emotion-recognition task. Finally, a traditional self-report questionnaire was used to assess their temperamental traits. The participants exhibited an unbalanced gut microbiota profile, along with impaired recognition of fearful expressions. Interestingly, dysbiosis was more severe in those participants with altered behavioral performance, with a decrease in typically health-associated microbes, and an increase in the potential pathobiont, Collinsella. Moreover, Collinsella was related to a lower expression of the persistence temperamental trait, while a higher expression of the harm-avoidance temperament, related to fear-driven anxiety symptoms, was linked to Lactobacillus. Once confirmed, our findings could pave the way for the design of innovative microbiome-based strategies for the treatment of psychological and emotional difficulties by mitigating obesity-related consequences and behaviors.

Hemispheric asymmetries for emotions in non-human primates: A systematic review

A systematic review of investigations evaluating hemispheric asymmetries for emotions in primates was undertaken to individuate the most consistent lines of research allowing to check the hypothesis of a continuum in emotional lateralization across vertebrates. We reviewed studies on the lateralization of emotional expression (N = 31) and perception (N = 32) and of markers of emotional activation (N = 9), trying to distinguish those which had given respectively more consistent or more conflicting outcomes. Furthermore, we tried to identify the most strongly supported model of emotional lateralization. The most consistent results were obtained in studies investigating asymmetries in emotional expression at the facial level and in the perception of emotional facial expressions, whereas the most disappointing data were obtained in investigations evaluating possible neurophysiological markers of lateralized emotional activation. These results supported more the hypothesis of a continuity between humans and non-human primates than the more general hypothesis of a continuum between humans and all vertebrates. Furthermore, results supported more the 'right hemisphere' than the 'valence' model of emotional lateralization.

Altered Brain Functional Asymmetry in Patients With Major Depressive Disorder Related to Gastrointestinal Symptoms

Objective

Disrupted brain functional asymmetry has been reported in major depressive disorder (MDD). The comorbidity may be a crucial factor to this functional asymmetry. It is quite common that gastrointestinal (GI) symptoms are comorbid with MDD, but limited evidence focuses on the effect of GI comorbidity on the neuropathology of MDD from a functional lateralization perspective.

Methods

Resting-state functional magnetic resonance imaging was obtained in 28 healthy controls (HCs), 35 MDD patients with GI symptoms (GI-MDD patients), and 17 patients with MDD without GI symptoms (nGI-MDD patients). The parameter of asymmetry (PAS) was used to analyze the imaging data and evaluate the changes of functional asymmetry.

Results

The GI-MDD patients showed increased PAS scores in the left inferior frontal gyrus (IFG) and superior medial prefrontal cortex (MPFC) and decreased PAS scores in the right postcentral gyrus in comparison with nGI-MDD patients. The PAS scores of the left IFG and left superior MPFC were correlated with the severity of GI problems and could be applied to distinguish GI-MDD patients from nGI-MDD patients with an accuracy, a sensitivity, and a specificity of 92.31, 100, and 76.47%, respectively. Furthermore, GI-MDD and nGI-MDD patients both displayed increased PAS scores in the PCC/precuneus.

Conclusions

This study revealed the influence of concomitant GI symptoms on functional asymmetry in MDD patients. Increased PAS scores of the left IFG and superior MPFC might represent an unbalanced regulation of brain over GI function and had the potential to be regarded as distinctive features related to functional GI symptoms in MDD.

Implicit facial emotion recognition of fear and anger in obesity

BACKGROUND

Previous evidence about facial emotion recognition capability in obesity is few and not conclusive.

OBJECTIVE

We investigated the capability of female individuals affected by obesity to recognize the emotions of fear and anger through a facial emotion recognition task grounded on the implicit redundant target effect.

METHODS

20 women affected by obesity and 20 healthy-weight women were enrolled. We administered an implicit facial emotion recognition task. Both reaction time and level of accuracy were computed. Moreover, the level of alexithymia was measured through the standard questionnaire.

RESULTS

Selective difficulties in recognizing the emotion of fear were observed in participants with obesity, when their performance was contrasted with healthy-weight controls. Instead, they showed the implicit redundant target effect when anger was the target. However, the two groups reported globally similar scores at the standard questionnaire relative to the level of alexithymia.

CONCLUSIONS

Our result might agree with the hypothesis about affected individuals' difficulties in being attentive to negative facial emotions, and specifically in the case of fearful expression. This study might encourage future research in which emotional processing will be investigated through subjective judgments and implicit/objective measurements.

LEVEL I

Experimental study.

Detection and Recognition of Fearful Facial Expressions During the Coronavirus Disease (COVID-19) Pandemic in an Italian Sample: An Online Experiment

In this observational study, the psychological ability to recognize the others' fearful expressions in Italian individuals during the pandemic COVID-19 lockdown was explored through a behavioral task performed online. An implicit version of the traditional facial emotion recognition task, grounded on the attentional and unconscious mechanism of the redundant target effect, was used. The experiment was scripted through the free software OpenSesame (Mathôt et al., 2012) and published on the Internet through the free software Jatos (Lange et al., 2015). The Reaction Time and level of Accuracy in detecting fearful expressions were computed. Overall, the data of 86 Italian individuals were collected. When their performance was scored in terms of Reaction Time, the redundant target effect did not emerge; instead, the expected effect was observed when the level of Accuracy was considered. Overall, the performance registered in this Italian sample in terms of accuracy was in line with previous results reported in Scarpina et al. (2018), in which a long extended version of the same behavioral task was used in a traditional experimental setting. This study might offer some considerations regarding the adoption of online experiments - together with self-report surveys - to assess the psychological and behavioral functioning during social restriction measures.

Altered white matter connectivity in young people exposed to childhood abuse: a tract-based spatial statistics (TBSS) and tractography study

BACKGROUND

Childhood abuse is associated with structural brain abnormalities. Few studies have investigated white matter tract abnormalities in medication-naive, drug-free individuals who experienced childhood abuse. We examined the association between childhood abuse and abnormalities in white matter tracts in that population, controlling for psychiatric comorbidities.

METHODS

We collected diffusion tensor imaging data for age- and sex-matched youth with childhood abuse, psychiatric controls (matched for psychiatric diagnoses) and healthy controls. Tract-specific analysis was conducted using tractography. Tract-based spatial statistics (TBSS) was used to assess group differences in fractional anisotropy (FA) at the whole-brain level.

RESULTS

We included 20 youth who experienced childhood abuse, 18 psychiatric controls and 25 healthy controls in our analysis. Tractography analysis showed abuse-specific reduced tract volume in the inferior longitudinal fasciculus (ILF) and inferior frontal-occipital fasciculus (IFoF) in the abuse group relative to both healthy and psychiatric controls. Furthermore, abnormalities in the left IFoF were associated with greater abuse severity. The TBSS analysis showed significantly reduced FA in a left-hemispheric cluster comprising the ILF, IFoF and corpus callosum splenium in the abuse group relative to healthy and psychiatric controls.

LIMITATIONS

It is unclear to what extent pubertal development, malnutrition and prenatal drug exposure may have influenced the findings.

CONCLUSION

Childhood abuse is associated with altered structure of neural pathways connecting the frontal, temporal and occipital cortices that are known to mediate affect and cognitive control. The abuse-specific deficits in the ILF and IFoF suggest that fibre tracts presumably involved in conveying and processing the adverse abusive experience are specifically compromised in this population.

Temporal Dynamics of Natural Static Emotional Facial Expressions Decoding: A Study Using Event- and Eye Fixation-Related Potentials

This study aims at examining the precise temporal dynamics of the emotional facial decoding as it unfolds in the brain, according to the emotions displayed. To characterize this processing as it occurs in ecological settings, we focused on unconstrained visual explorations of natural emotional faces (i.e., free eye movements). The General Linear Model (GLM; Smith and Kutas, 2015a,b; Kristensen et al., 2017a) enables such a depiction. It allows deconvolving adjacent overlapping responses of the eye fixation-related potentials (EFRPs) elicited by the subsequent fixations and the event-related potentials (ERPs) elicited at the stimuli onset. Nineteen participants were displayed with spontaneous static facial expressions of emotions (Neutral, Disgust, Surprise, and Happiness) from the DynEmo database (Tcherkassof et al., 2013). Behavioral results on participants' eye movements show that the usual diagnostic features in emotional decoding (eyes for negative facial displays and mouth for positive ones) are consistent with the literature. The impact of emotional category on both the ERPs and the EFRPs elicited by the free exploration of the emotional faces is observed upon the temporal dynamics of the emotional facial expression processing. Regarding the ERP at stimulus onset, there is a significant emotion-dependent modulation of the P2-P3 complex and LPP components' amplitude at the left frontal site for the ERPs computed by averaging. Yet, the GLM reveals the impact of subsequent fixations on the ERPs time-locked on stimulus onset. Results are also in line with the valence hypothesis. The observed differences between the two estimation methods (Average vs. GLM) suggest the predominance of the right hemisphere at the stimulus onset and the implication of the left hemisphere in the processing of the information encoded by subsequent fixations. Concerning the first EFRP, the Lambda response and the P2 component are modulated by the emotion of surprise compared to the neutral emotion, suggesting an impact of high-level factors, in parieto-occipital sites. Moreover, no difference is observed on the second and subsequent EFRP. Taken together, the results stress the significant gain obtained in analyzing the EFRPs using the GLM method and pave the way toward efficient ecological emotional dynamic stimuli analyses.

The theta burst transcranial magnetic stimulation over the right PFC affects electroencephalogram oscillation during emotional processing

Prefrontal cortex (PFC) plays an important role in emotional processing and therefore is one of the most frequently targeted regions for non-invasive brain stimulation such as repetitive transcranial magnetic stimulation (rTMS) in clinical trials, especially in the treatment of emotional disorders. As an approach to enhance the effectiveness of rTMS, continuous theta burst stimulation (cTBS) has been demonstrated to be efficient and safe. However, it is unclear how cTBS affects brain processes related to emotion. In particular, psychophysiological studies on the underlying neural mechanisms are sparse. In the current study, we investigated how the cTBS influences emotional processing when applied over the right PFC. Participants performed an emotion recognition Go/NoGo task, which asked them to select a GO response to either happy or fearful faces after the cTBS or after sham stimulation, while 64-channel electroencephalogram (EEG) was recorded. EEG oscillation was examined using event-related spectral perturbation (ERSP) in a time-interval between 170 and 310ms after face stimuli onset. In the sham group, we found a significant difference in the alpha band between response to happy and fearful stimuli but that effect did not exist in the cTBS group. The alpha band activity at the scalp was reduced suggesting the excitatory effect at the brain level. The beta and gamma band activity was not sensitive to cTBS intervention. The results of the current study demonstrate that cTBS does affect emotion processing and the effect is reflected in changes in EEG oscillations in the alpha band specifically. The results confirm the role of prefrontal cortex in emotion processing. We also suggest that this pattern of cTBS results elucidates mechanisms by which mood improvement in depressive disorders is achieved using cTBS intervention.

Absence of distracting information explains the redundant signals effect for a centrally presented categorization task

The redundant signals effect, a speed-up in response times with multiple targets compared to a single target in one display, is well-documented, with some evidence suggesting that it can occur even in conceptual processing when targets are presented bilaterally. The current study was designed to determine whether or not category-based redundant signals can speed up processing even without bilateral presentation. Toward that end, participants performed a go/no-go visual task in which they responded only to members of the target category (i.e., they responded only to numbers and did not respond to letters). Numbers and letters were presented along an imaginary vertical line in the center of the visual field. When the single signal trials contained a nontarget letter (Experiment 1), there was a significant redundant signals effect. The effect was not significant when the single-signal trials did not contain a nontarget letter (Experiments 2 and 3). The results indicate that, when targets are defined categorically and not presented bilaterally, the redundant signals effect may be an effect of reducing the presence of information that draws attention away from the target. This suggests that redundant signals may not speed up conceptual processing when interhemispheric presentation is not available.

Reduced white matter integrity and facial emotion perception in never-medicated patients with first-episode schizophrenia: A diffusion tensor imaging study

BACKGROUND

Facial emotion perception is impaired in schizophrenia. Although the pathology of schizophrenia is thought to involve abnormality in white matter (WM), few studies have examined the correlation between facial emotion perception and WM abnormalities in never-medicated patients with first-episode schizophrenia. The present study tested associations between facial emotion perception and WM integrity in order to investigate the neural basis of impaired facial emotion perception in schizophrenia.

METHODS

Sixty-three schizophrenic patients and thirty control subjects underwent facial emotion categorization (FEC). The FEC data was inserted into a logistic function model with subsequent analysis by independent-samples T test and the shift point and slope as outcome measurements. Severity of symptoms was measured using a five-factor model of the Positive and Negative Syndrome Scale (PANSS). Voxelwise group comparison of WM fractional anisotropy (FA) was operated using tract-based spatial statistics (TBSS). The correlation between impaired facial emotion perception and FA reduction was examined in patients using simple regression analysis within brain areas that showed a significant FA reduction in patients compared with controls. The same correlation analysis was also performed for control subjects in the whole brain.

RESULTS

The patients with schizophrenia reported a higher shift point and a steeper slope than control subjects in FEC. The patients showed a significant FA reduction in left deep WM in the parietal, temporal and occipital lobes, a small portion of the corpus callosum (CC), and the corona radiata. In voxelwise correlation analysis, we found that facial emotion perception significantly correlated with reduced FA in various WM regions, including left forceps major (FM), inferior longitudinal fasciculus (ILF), inferior fronto-occipital fasciculus (IFOF), Left splenium of CC, and left ILF. The correlation analyses in healthy controls revealed no significant correlation of FA with FEC task.

CONCLUSIONS

These results showed disrupted WM integrity in these regions constitutes a potential neural basis for the facial emotion perception impairments in schizophrenia.

Brain Activation Follows Adding-Type Integration Laws: Brain and Rating Responses in an Integration Task with pairs of Emotional Faces

This study was designed to investigate the relation between rating responses and the patterns of cortical activation in an integration task using pairs of emotional faces. Participants judged on a graphic rating scale the overall affective intensity conveyed by two emotional faces, each presented to one of the two hemispheres via a Divided Visual Field technique (DVF). While they performed the task, EEG was recorded from 6 scalp locations. Three discrete emotions were considered (Joy, Fear, and Anger) and varied across three levels of expression intensity. Some face pairs portrayed the same emotion (same-emotion pairs), others two different emotions (distinct-emotions pairs). The patterns of integration of the two sources of information were examined both at the level of the ratings and of the brain response (event-related-#-desynchronization: ERD) recorded at each EEG lead. Adding-type rules were found for the ratings of both same-emotion and different-emotions pairs. Addingtype integration was also commonly found when #-ERD was taken as a response. Outcomes are discussed with a link to the lateralization of emotional processing and the relations between the observable R (e.g., ratings) and possible implementational aspects of the implicit R posited by Information Integration Theory (IIT).

Effects of Unilateral Transcranial Direct Current Stimulation of Left Prefrontal Cortex on Processing and Memory of Emotional Visual Stimuli

The dorsolateral prefrontal cortex (DLPFC) is generally thought to be involved in affect and emotional processing; however, the specific contribution of each hemisphere continues to be debated. In the present study, we employed unilateral tDCS to test the unique contribution of left DLPFC in the encoding and retrieval of emotional stimuli in healthy subjects. Forty-two right handed undergraduate students received either anodal, cathodal or sham stimulation of left DLPFC while viewing neutral, pleasant, and unpleasant pictures. After completing a filler task, participants were asked to remember as many pictures as possible. Results showed that participants were able to remember a larger amount of emotional (both pleasant and unpleasant) pictures than of neutral ones, regardless of the type of tDCS condition. Participants who received anodal stimulation recalled a significantly higher number of pleasant images than participants in the sham and cathodal conditions, while no differences emerged in the recall of neutral and unpleasant pictures. We conclude that our results provide some support to the role of left prefrontal cortex in the encoding and retrieval of pleasant stimuli.

Depressive signs and cognitive performance in patients with a right hemisphere stroke

PURPOSE

This study investigated the influence of suggestive signs of depression (SSD) in right-hemisphere brain-damaged (RHD) patients following a stroke on their cognitive performance measured by a brief neuropsychological assessment battery.

METHODS

Forty-two adults with RHD after a single episode of stroke and 84 matched controls participated in this study. They were assessed by means of the Geriatric Depression Scale and by Brief Neuropsychological Assessment Battery NEUPSILIN.

RESULTS

Almost half of the patients showed SSD. The RHD group with SSD (RHD+) showed poorer performance in at least one task among all evaluated cognitive domains (concentrated attention, visual perception, working memory, episodic verbal memory and semantic memory, auditory and written language, constructional praxia and verbal fluency).

CONCLUSION

The association of depression and RHD seems to enhance the occurrence and the severity of cognitive déficits. A brief neuropsychological assessment can be useful to identify cognitive impairment caused by this neuropsychiatric disorder.

Unseen Fearful Faces Influence Face Encoding: Evidence from ERPs in Hemianopic Patients

Visual threat-related signals are not only processed via a cortical geniculo-striatal pathway to the amygdala but also via a subcortical colliculo-pulvinar-amygdala pathway, which presumably mediates implicit processing of fearful stimuli. Indeed, hemianopic patients with unilateral damage to the geniculo-striatal pathway have been shown to respond faster to seen happy faces in their intact visual field when unseen fearful faces were concurrently presented in their blind field [Bertini, C., Cecere, R., & Làdavas, E. I am blind, but I “see” fear. Cortex, 49, 985–993, 2013]. This behavioral facilitation in the presence of unseen fear might reflect enhanced processing of consciously perceived faces because of early activation of the subcortical pathway for implicit fear perception, which possibly leads to a modulation of cortical activity. To test this hypothesis, we examined ERPs elicited by fearful and happy faces presented to the intact visual field of right and left hemianopic patients, whereas fearful, happy, or neutral faces were concurrently presented in their blind field. Results showed that the amplitude of the N170 elicited by seen happy faces was selectively increased when an unseen fearful face was concurrently presented in the blind field of right hemianopic patients. These results suggest that when the geniculo-striate visual pathway is lesioned, the rapid and implicit processing of threat signals can enhance facial encoding. Notably, the N170 modulation was only observed in left-lesioned patients, favoring the hypothesis that implicit subcortical processing of fearful signals can influence face encoding only when the right hemisphere is intact.

The influence of emotional faces on the spatial allocation of attention

OBJECTIVES

Studies suggest that the right hemisphere is dominant for emotional facial recognition. In addition, whereas some studies suggest the right hemisphere mediates the processing of all emotions (dominance hypothesis), other studies suggest that the left hemisphere mediates positive emotions the right mediates negative emotions (valence hypothesis). Since each hemisphere primarily attends to contralateral space, the goals of this study was to learn if emotional faces would induce a leftward deviation of attention and if the valence of facial emotional stimuli can influence the normal viewer's spatial direction of attention.

METHODS

Seventeen normal right handed participants were asked to bisect horizontal lines that had all combinations of sad, happy or neutral faces at ends of these lines. During this task the subjects were never requested to look at these faces and there were no task demands that depended on viewing these faces.

RESULTS

Presentation of emotional faces induced a greater leftward deviation compared to neutral faces, independent of where (spatial position) these faces were presented. However, faces portraying negative emotions tended to induce a greater leftward bias than positive emotions.

CONCLUSIONS

Independent of location, the presence of emotional faces influenced the spatial allocation of attention, such that normal subjects shift the direction of their attention toward left hemispace and this attentional shift appears to be greater for negative (sad) than positive faces (happy).

Transcranial magnetic stimulation reveals two functionally distinct stages of motor cortex involvement during perception of emotional body language

Studies indicate that perceiving emotional body language recruits fronto-parietal regions involved in action execution. However, the nature of such motor activation is unclear. Using transcranial magnetic stimulation (TMS) we provide correlational and causative evidence of two distinct stages of motor cortex engagement during emotion perception. Participants observed pictures of body expressions and categorized them as happy, fearful or neutral while receiving TMS over the left or right motor cortex at 150 and 300 ms after picture onset. In the early phase (150 ms), we observed a reduction of excitability for happy and fearful emotional bodies that was specific to the right hemisphere and correlated with participants’ disposition to feel personal distress. This ‘orienting’ inhibitory response to emotional bodies was also paralleled by a general drop in categorization accuracy when stimulating the right but not the left motor cortex. Conversely, at 300 ms, greater excitability for negative, positive and neutral movements was found in both hemispheres. This later motor facilitation marginally correlated with participants’ tendency to assume the psychological perspectives of others and reflected simulation of the movement implied in the neutral and emotional body expressions. These findings highlight the motor system’s involvement during perception of emotional bodies. They suggest that fast orienting reactions to emotional cues—reflecting neural processing necessary for visual perception—occur before motor features of the observed emotional expression are simulated in the motor system and that distinct empathic dispositions influence these two neural motor phenomena. Implications for theories of embodied simulation are discussed.

Redundancy gain in semantic categorisation

Redundancy gain refers to the performance enhancements often associated with the presentation of redundant versus single targets (for example, faster, more accurate, or more forceful responses). Though predominantly observed in relatively simple tasks (e.g., stimulus detection), there have been some efforts to investigate similar phenomena in tasks involving higher level processing. We conducted three experiments aimed at determining (a) whether a redundancy gain would be evident in a task unambiguously requiring higher level processing (the semantic categorisation of visually-presented lexical stimuli), and (b) if so, what accounts might be appropriate to explain such findings. We found that redundancy gains are observed in such tasks, and we conclude that both coactivation and race models can account for these gains.

Redundancy effects in the processing of emotional faces

How does the visual system represent the ensemble statistics of visual objects? This question has received intense interest in vision research, yet most studies have focused on the extraction of mean statistics rather than its dispersion. This study focuses on another aspect of ensemble statistics: the redundancy of the sample. In two experiments, participants were faster judging the facial expression and gender of multiple faces than a single face. The redundancy gain was equivalent for multiple identical faces and for multiple faces of different identities. To test whether the redundancy gain was due to increased strength in perceptual representation, we measured the magnitude of facial expression aftereffects. The aftereffects were equivalent when induced by a single face and by four identical faces, ruling out increased perceptual strength as an explanation for the redundancy gain. We conclude that redundant faces facilitate perception by enhancing the robustness of representation of each face.

Please don't! The automatic extrapolation of dangerous intentions

Facial emotions and emotional body postures can easily grab attention in social communication. In the context of faces, gaze has been shown as an important cue for orienting attention, but less is known for other important body parts such as hands. In the present study we investigated whether hands may orient attention due to the emotional features they convey. By implying motion in static photographs of hands, we aimed at furnishing observers with information about the intention to act and at testing if this interacted with the hand automatic coding. In this study, we compared neutral and frontal hands to emotionally threatening hands, rotated along their radial-ulnar axes in a Sidedness task (a Simon-like task based on automatic access to body representation). Results showed a Sidedness effect for both the palm and the back views with either neutral and emotional hands. More important, no difference was found between the two views for neutral hands, but it emerged in the case of the emotional hands: faster reaction times were found for the palm than the back view. The difference was ascribed to palm views' “offensive” pose: a source of threat that might have raised participants' arousal. This hypothesis was also supported by conscious evaluations of the dimensions of valence (pleasant-unpleasant) and arousal. Results are discussed in light of emotional feature coding.

Social cognition in anorexia nervosa: evidence of preserved theory of mind and impaired emotional functioning

BACKGROUND

The findings of the few studies that have to date investigated the way in which individuals with Anorexia Nervosa (AN) navigate their social environment are somewhat contradictory. We undertook this study to shed new light on the social-cognitive profile of patients with AN, analysing Theory of Mind and emotional functioning. Starting from previous evidence on the role of the amygdala in the neurobiology of AN and in the social cognition, we hypothesise preserved Theory of Mind and impaired emotional functioning in patients with AN.

METHODOLOGY

Thirty women diagnosed with AN and thirty-two women matched for education and age were involved in the study. Theory of Mind and emotional functioning were assessed with a set of validated experimental tasks. A measure of perceived social support was also used to test the correlations between this dimension and the social-cognitive profile of AN patients.

PRINCIPAL FINDINGS

The performance of patients with AN is significantly worse than that of healthy controls on tasks assessing emotional functioning, whereas patients' performance is comparable to that of healthy controls on the Theory of Mind task. Correlation analyses showed no relationship between scores on any of the social-cognition tasks and either age of onset or duration of illness. A correlation between social support and emotional functioning was found. This latter result seems to suggest a potential role of social support in the treatment and recovery of AN.

CONCLUSIONS

The pattern of results followed the experimental hypothesis. They may be useful to help us better understand the social-cognitive profile of patients with AN and to contribute to the development of effective interventions based on the ways in which patients with AN actually perceive their social environment.

Resting electrocortical activity in adults with dysfunctional anger: a pilot study

Although dysfunctional anger is not a DMS diagnosis, some individuals present with dysfunctional anger, to the exclusion of other psychiatric disorders, as the primary clinical feature. However, our understanding of the neural basis of dysfunctional anger is limited. Though previous work has examined electroencephalographic (EEG) activity in individuals with high trait anger, and in youth with disorders consistent with dysfunctional anger, no studies have assessed EEG activity in adults with dysfunctional anger. This study examined resting EEG by way of relative power in the beta and alpha bands, as well as absolute frontal and parietal alpha(1/2) asymmetry, in 15 adults with psychiatrist-assessed and psychometrically rated dysfunctional anger (Anger) and 14 control participants (Control). The Anger group had increased overall relative beta(1) power during both eyes-open and closed conditions. Inconsistent with most precedent literature, the Anger group also exhibited greater relative right fronto-cortical activation (alpha(1)-indexed frontal asymmetry) during the eyes-closed condition. This may reflect greater anxious arousal and/or compensatory activation of inhibitory tendencies associated with right frontal activation in individuals with dysfunctional anger. Enhanced beta(1) activity may index greater tonic cortical arousal or a chronic hypervigilant state, which may predispose individuals with dysfunctional anger to over-react to relatively innocuous stimuli.

Evidence for a left-over-right inhibitory mechanism during figural creative thinking in healthy nonartists

As a complex mental process, creativity requires the coordination of multiple brain regions. Previous pathological research on figural creativity has indicated that there is a mechanism by which the left side of the brain inhibits the activities of the right side of the brain during figural creative thinking, but this mechanism has not been directly demonstrated. In this study, we used functional magnetic resonance imaging (fMRI) to demonstrate the existence of this inhibitory mechanism in young adults (15 women, 11 men, mean age: 22 years) that were not artists. By making comparisons between brain activity during creative and uncreative tasks, we found increased activity in the left middle and inferior frontal lobe and strong decreases in activity in the right middle frontal lobe and the left inferior parietal lobe. As such, these data suggest that the left frontal lobe may inhibit the right hemisphere during figural creative thinking in normal people. Moreover, removal of this inhibition by practicing artistry or through specific damage to the left frontal lobe may facilitate the emergence of artistic creativity.

Islamic Headdress Influences How Emotion is Recognized from the Eyes

Previous research has shown a negative bias in the perception of whole facial expressions from out-group members. Whether or not emotion recognition from the eyes is already sensitive to contextual information is presently a matter of debate. In three experiments we tested whether emotions can be recognized when just the eyes are visible and whether this recognition is affected by context cues, such as various Islamic headdresses vs. a cap or a scarf. Our results indicate that fear is still well recognized from a briefly flashed (100 ms) image of a women wearing a burqa with less than 20% transparency of the eye region. Moreover, the type of headdress influences how emotions are recognized. In a group of participants from non-Islamic background, fear was recognized better from women wearing a niqāb than from women wearing a cap and a shawl, whereas the opposite was observed for happy and sad expressions. The response patterns showed that fearful and anger labels were more often attributed to women with a niqāb vs. a cap and a shawl and again, an opposite pattern was observed for the happy response. However, there was no general response bias: both correct and incorrect responses were influenced by the facial expression as well. Anxiety levels and/or explicit negative associations with the Islam as measured via questionnaires did not mediate the effects. Consistent with the face literature, we conclude that the recognition of emotions from the eyes is also influenced by context.

Tomada de decisão no IGT: estudo de caso pós-AVC de hemisfério direito versus esquerdo

Investigou comparativamente o processo de tomada de decisão de dois adultos pós-AVC unilateral e verificar o papel da lateralidade hemisférica na performance do Iowa Gambling Task (IGT). Participaram um adulto com lesão de hemisfério direito (LHD) e outro com lesão de hemisfério esquerdo (LHE), ambos pós-AVC isquêmico subcortical. O IGT foi utilizado para avaliar a tomada de decisão. Os pacientes apresentaram um desempenho adequado no IGT, demonstrando ter uma boa capacidade de tomar decisão. No entanto, somente o paciente com LHD apresentou uma curva sugestiva de aprendizagem. Esses dados indicam que uma lesão subcortical independente do hemisfério pode não interferir no desempenho do IGT. Sugere-se que estudos de grupos sejam conduzidos buscando comparar pacientes com lesão frontal e não-frontal, auxiliando na caracterização do processo de tomada de decisão na população com lesão vascular unilateral.

The neural correlates of emotional prosody comprehension: disentangling simple from complex emotion

Background

Emotional prosody comprehension (EPC), the ability to interpret another person's feelings by listening to their tone of voice, is crucial for effective social communication. Previous studies assessing the neural correlates of EPC have found inconsistent results, particularly regarding the involvement of the medial prefrontal cortex (mPFC). It remained unclear whether the involvement of the mPFC is linked to an increased demand in socio-cognitive components of EPC such as mental state attribution and if basic perceptual processing of EPC can be performed without the contribution of this region.

Methods

fMRI was used to delineate neural activity during the perception of prosodic stimuli conveying simple and complex emotion. Emotional trials in general, as compared to neutral ones, activated a network comprising temporal and lateral frontal brain regions, while complex emotion trials specifically showed an additional involvement of the mPFC, premotor cortex, frontal operculum and left insula.

Conclusion

These results indicate that the mPFC and premotor areas might be associated, but are not crucial to EPC. However, the mPFC supports socio-cognitive skills necessary to interpret complex emotion such as inferring mental states. Additionally, the premotor cortex involvement may reflect the participation of the mirror neuron system for prosody processing particularly of complex emotion.

Processing emotion from the eyes: a divided visual field and ERP study

The right cerebral hemisphere is preferentially involved in recognising at least some facial expressions of emotion. We investigated whether there is a laterality effect in judging emotions from the eyes. In one task a pair of emotionally expressive eyes presented in central vision had to be physically matched to a subsequently presented set of eyes in one or other visual hemifield (eyes condition). In the second task a word was presented centrally followed by a set of eyes to left or right hemifield and the participant had to decide whether the word correctly described the emotion portrayed by the laterally presented set of eyes (word condition). Participants were a group of undergraduate students and a group of older volunteers (> 50). There was no visual hemifield difference in accuracy or raw response times in either task for either group, but log-transformed times showed an overall left hemifield advantage. Contrary to the right hemisphere ageing hypothesis, older participants showed no evidence of a relative right hemisphere decline in performance on the tasks. In the younger group mean peak amplitude of the N170 component of the EEG at lateral posterior electrode sites was significantly greater over the right hemisphere (T6/PO2) than the left (T5/PO1) in both the perceptual recognition task and the emotional judgement task. It was significantly greater for the task of judging emotion than in the eyes-matching task. In future it would be useful to combine electrophysiological techniques with lateralised visual input in studying lateralisation of emotion with older as well as younger participants.

Is borderline personality a particularly right hemispheric disorder? A study of P3a using single trial analysis

OBJECTIVE

To test the hypothesis that borderline personality disorder is a manifestation of a particularly right hemispheric disturbance, involving deficient higher order inhibition, and to consider the therapeutic implications of the findings.

METHODS

A cohort of 17 medication free borderline patients were compared with 17 age and sex matched controls by means of a study of p3a, which reflects the activity of one of the two main generators of the P300 (P3) of the event-related-potential. P3b reflects the output of the other generator. P3a, an aspect of the attentional system, depends upon prefrontally connected neurocircuitry. P3b is underpinned by a particularly parietally connected neural system. Using an oddball paradigm, P3a was extracted from the responses to targets using a novel single trial analysis.

RESULTS

In borderline patients, over homologous electrode sites, p3a amplitudes, but not latencies, were significantly larger in the right hemisphere compared with the left. The differences were most marked fronto-centrally. No such difference was shown in the control subjects. P3a at right hemisphere sites was significantly larger in borderline compared with control patients. There was no significant difference between the groups for the left hemisphere sites.

CONCLUSIONS

The abnormally large amplitudes of P3a at right hemisphere sites in borderline patients together with the failure of habituation of P3a, are consistent with deficient inhibitory activity. Discussion of the findings suggest that they may reflect impeded maturation of the fronto-medial processing systems which, it is argued, may be a consequence of the typical early environment of those with the borderline condition. This suggestion leads to a consideration of optimal therapeutic behaviour in this condition, in particular for 'matching' or 'analogical' responsiveness.

Neural bases of the non-conscious perception of emotional signals

Many emotional stimuli are processed without being consciously perceived. Recent evidence indicates that subcortical structures have a substantial role in this processing. These structures are part of a phylogenetically ancient pathway that has specific functional properties and that interacts with cortical processes. There is now increasing evidence that non-consciously perceived emotional stimuli induce distinct neurophysiological changes and influence behaviour towards the consciously perceived world. Understanding the neural bases of the non-conscious perception of emotional signals will clarify the phylogenetic continuity of emotion systems across species and the integration of cortical and subcortical activity in the human brain.

Reduced white matter integrity as a neural correlate of social cognition deficits in schizophrenia

BACKGROUND

The pathology of schizophrenia is thought to involve multiple gray and white matter regions. A number of studies have revealed impaired social cognition in schizophrenia. Some evidence suggests an association of this social cognition deficit with gray matter reductions in 'social brain' areas. However, no study has yet revealed the association between social cognition abilities and white matter abnormalities in schizophrenia patients.

METHODS

Twenty-six schizophrenia patients and 27 healthy controls underwent the Perception of Affect Task (PAT), which consisted of four subtasks measuring different aspects of emotion attribution. Voxelwise group comparison of white matter fractional anisotropy (FA) was performed using tract-based spatial statistics (TBSS). The relation between impaired social cognition ability and FA reduction was examined in patients for each subtask, using simple regression analysis within brain areas that showed a significant FA reduction in patients compared with controls. The same correlational analysis was also performed for healthy controls in the whole brain.

RESULTS

Schizophrenia patients showed reduced emotion attribution ability compared with controls in all four subtasks. The facial emotion perception subtask showed a significant correlation with FA reductions in the left occipital white matter region and left posterior callosal region. The correlational analyses in healthy controls revealed no significant correlation of FA with any of the PAT subtasks.

CONCLUSIONS

Our voxelwise correlational analysis of white matter provided a potential neural basis for the social cognition impairments in schizophrenia, in support of the disconnection hypothesis.

Selective feeding in birds depends on combined processing in the left and right brain hemisphere

During visually guided foraging birds tend to select certain types of food from a mixed diet. This selectivity is ecologically relevant. During scanning for food birds spot the surroundings mainly with the monocular lateral visual field of the one or other eye and then control pecking with their small binocular frontal visual field. As the visual systems of the avian left and right brain hemisphere are supposed to work largely independently in the short term, the problem arises of how the avian brain handles a task that requires coordinated activity of the left and right brain hemisphere for efficient processing. Here we report that chicks exhibit strong selective feeding when both of the brain hemispheres are involved. With the left or right hemisphere alone selectivity is reduced or completely absent. Our findings reveal a marked qualitative difference between unilateral and bilateral processing. They highlight an important but so far unexplored selection pressure for the evolution of hemispheric cooperation.

Fast recognition of social emotions takes the whole brain: Interhemispheric cooperation in the absence of cerebral asymmetry

Hemispheric asymmetry in emotional perception has been traditionally studied for basic emotions and very little is known about laterality for more complex social emotions. Here, we used the "redundant target paradigm" to investigate interhemispheric asymmetry and cooperation for two social emotions in healthy subjects. Facial expressions of flirtatiousness or arrogance were briefly presented either unilaterally in the left (LVF) or right visual field (RVF), or simultaneously to both visual fields (BVF) while participants responded to the target expression (flirtatious or arrogant, counterbalanced between blocks). In bilateral conditions the faces could show the same emotion (congruent condition) or two different expressions (incongruent condition). No difference between unilateral presentations was found, suggesting that the perception of social emotions is not hemispherically lateralized. Responses were faster and more accurate in bilateral displays with two emotionally congruent but physically different faces (i.e., a male and a female expressing the same emotion) than in unilateral conditions. This "redundant target effect" was consistent with a neural summation model, thereby showing that interhemispheric cooperation may occur for social emotions despite major perceptual differences between faces posing the same expression.

Chapter 3 Beyond the face: exploring rapid influences of context on face processing

Humans optimize behavior by deriving context-based expectations. Contextual data that are important for survival are extracted rapidly, using coarse information, adaptive decision strategies, and dedicated neural infrastructure. In the field of object perception, the influence of a surrounding context has been a major research theme, and it has generated a large literature. That visual context, as typically provided by natural scenes, facilitates object recognition as has been convincingly demonstrated (Bar, M. (2004) Nat. Rev. Neurosci., 5: 617-629). Just like objects, faces are generally encountered as part of a natural scene. Thus far, the facial expression literature has neglected such context and treats facial expressions as if they stand on their own. This constitutes a major gap in our knowledge. Facial expressions tend to appear in a context of head and body orientations, body movements, posture changes, and other object-related actions with a similar or at least a closely related meaning. For instance, one would expect a frightened face when confronted to an external danger to be at least accompanied by withdrawal movements of head and shoulders. Furthermore, some cues provided by the environment or the context in which a facial expression appears may have a direct relation with the emotion displayed by the face. The brain may even fill in the natural scene context typically associated with the facial expression. Recognition of the facial expression may also profit from processing the vocal emotion as well as the emotional body language that normally accompany it. Here we review the emerging evidence on how the immediate visual and auditory contexts influence the recognition of facial expressions.