Effects of lesion variables and emotion type on the perception of facial emotion

[Alexithymia in Multiple Sclerosis - Narrative Review]

Alexithymia is a multidimensional construct of personality implicating difficulties in identifying and describing another's feelings, and externally oriented thinking. It is broadly reported in psychiatric patients but has gained little attention regarding its occurrence and pathophysiology in multiple sclerosis (MS). This narrative review aims to address prevalence, etiology, neurobiological, and clinical findings of alexithymia. The prevalence of alexithymia in MS ranges from 10 to 53%. There seems to be an association with anxiety, depression, fatigue, and some aspects of social cognition, while the relationship with clinical and classical cognitive variables was rarely evaluated. Only a few studies referred to its pathophysiology assuming an aberrant interhemispheric transfer or regional cerebral abnormalities. The prevalence of alexithymia in MS and the potential negative impact on quality of life and interpersonal communication could severely impact clinical MS management and a screnning for these factors should be mandatory. Thus, further evaluation is needed concerning its relationship with clinical, emotional, and cognitive confounders. Large-scale studies employing neuroimaging techniques are needed for a better understanding of the neural underpinnings of this MS feature.

EEG decoding of multidimensional information from emotional faces

Humans can detect and recognize faces quickly, but there has been little research on the temporal dynamics of the different dimensional face information that is extracted. The present study aimed to investigate the time course of neural responses to the representation of different dimensional face information, such as age, gender, emotion, and identity. We used support vector machine decoding to obtain representational dissimilarity matrices of event-related potential responses to different faces for each subject over time. In addition, we performed representational similarity analysis with the model representational dissimilarity matrices that contained different dimensional face information. Three significant findings were observed. First, the extraction process of facial emotion occurred before that of facial identity and lasted for a long time, which was specific to the right frontal region. Second, arousal was preferentially extracted before valence during the processing of facial emotional information. Third, different dimensional face information exhibited representational stability during different periods. In conclusion, these findings reveal the precise temporal dynamics of multidimensional information processing in faces and provide powerful support for computational models on emotional face perception.

Psychiatric sequelae of stroke affecting the non-dominant cerebral hemisphere

There are a plethora of cognitive sequelae in addition to neglect and extinction that arise with unilateral right hemispheric stroke (RHS). Cognitive deficits following non-dominant (right) hemisphere stroke are common with unilateral neglect and extinction being the most recognized examples. The severity of RHS is usually underestimated by the National Institutes of Health Stroke Scale (NIHSS), which in terms of lateralized right hemisphere cognitive deficits, tests only for visual inattention/extinction. They account for 2 out of 42 total possible points. Additional neuropsychiatric sequelae include but are not limited to deficiencies in affective prosody comprehension and production (aprosodias), understanding and expressing facial emotions, empathy, recognition of familiar faces, anxiety, mania, apathy, and psychosis. These sequelae have a profound impact on patients' quality of life; affecting communication, interpersonal relationships, and the ability to fulfill social roles. They also pose additional challenges to recovery. There is presently a gap in the literature regarding a cohesive overview of the significant cognitive sequelae following RHS. This paper serves as a narrative survey of the current understanding of the subject, with particular emphasis on neuropsychiatric poststroke syndromes not predominantly associated with left hemisphere lesions (LHL), bilateral lesions, hemiplegia, or paralysis. A more comprehensive understanding of the neuropsychological consequences of RHS extending beyond the typical associations of unilateral neglect and extinction may have important implications for clinical practice, including the ways in which clinicians approach diagnostics, treatment, and rehabilitation.

Disorders of facial emotional expression and comprehension

One of the most important means of communicating emotions is by facial expressions. About 30-40 years ago, several studies examined patients with right and left hemisphere strokes for deficits in expressing and comprehending emotional facial expressions. The participants with right- or left-hemispheric strokes attempted to determine if two different actors were displaying the same or different emotions, to name the different emotions being displayed, and to select the face displaying an emotion named by the examiner. Investigators found that the right hemisphere-damaged group was impaired on all these emotional facial tests and that this deficit was not solely related to visuoperceptual processing defects. Further studies revealed that the patients who were impaired at recognizing emotional facial expressions and who had lost these visual representations of emotional faces often had damage to their right parietal lobe and their right somatosensory cortex. Injury to the cerebellum has been reported to impair emotional facial recognition, as have dementing diseases such as Alzheimer's disease and frontotemporal dementia, movement disorders such as Parkinson's disease and Huntington's disease, traumatic brain injuries, and temporal lobe epilepsy. Patients with right hemisphere injury are also more impaired than left-hemisphere-damaged patients when attempting to voluntarily produce facial emotional expressions and in their spontaneous expression of emotions in response to stimuli. This impairment does not appear to be induced by emotional conceptual deficits or an inability to experience emotions. Many of the disorders that cause impairments of comprehension of affective facial expressions also impair facial emotional expression. Treating the underlying disease may help patients with impairments of facial emotion recognition and expression, but unfortunately, there have not been many studies of rehabilitation.

Neuro-cognitive correlates of alexithymia in patients with circumscribed prefrontal cortex damage

Alexithymia has been extensively reported in studies of psychiatric patients. However, little attention has been paid regarding its occurrence in the context of patients with circumscribed prefrontal cortex lesions. Moreover, the neuro-cognitive impairments that lead to alexithymia remain unclear and limited numbers of studies have addressed these issues. The authors investigated the impact of prefrontal cortex lesions on alexithymia and its neuro-cognitive correlates in a population of 20 patients with focal frontal lesions, 10 patients with parietal lesions and 34 matched control participants. Alexithymia was screened using the Toronto Alexithymia Scale (TAS-20) and executive functions were assessed using a large battery of executive tasks that address inhibition, flexibility and the planning process. Results showed that patients with prefrontal cortex damage showed significantly increased difficulty in facets of identifying feelings (DIF) and externally oriented thinking (EOT) on TAS-20, compared to parietal patients and control participants. Moreover, both correlation and regression analysis revealed that higher alexithymia levels on the three facets of TAS-20 were consistently but differentially associated with impairment in inhibition, flexibility and planning tasks for frontal patients and both control groups. These findings provide clinical evidence of the implication of prefrontal cortex damage and executive control in alexithymia. Our results were also discussed in the light of the cognitive appraisal concept as a mechanism involved in emotion episode processing. This study suggests that increased neuropsychological attention should be directed to the relation between the neuro-cognitive model of executive functions and cognitive appraisal theory in processing emotion.

Impaired Emotion Recognition after Left Hemispheric Stroke: A Case Report and Brief Review of the Literature

Impaired recognition of emotion after stroke can have important implications for social competency, social participation, and consequently quality of life. We describe a case of left hemispheric ischemic stroke with impaired recognition of specifically faces expressing fear. Three months later, the patient's spouse reports that the patient was irritable and slow in communication, which may be caused by the impaired emotion recognition. The case is discussed in relation to the literature concerning emotion recognition and its neural correlates. Our case supports the notion that emotion recognition, including fear recognition, is regulated by a network of interconnected brain regions located in both hemispheres. We conclude that impaired emotion recognition is not uncommon after stroke and can be caused by dysfunction of this emotion-network.

Brain Lateralization of Emotional Processing: Historical Roots and a Future Incorporating “Dominance”

This article provides a review of research on the hemispheric specialization in emotional processing during the past 40 years and the theoretical models derived from the conceptual analysis of these results. The publications reviewed here were collected to better appreciate the cortical lateralization of emotional perception (visual and auditory), expression (facial and prosodic), and experience. Four major models of emotional processing are discussed—the Right Hemisphere, Valence, Approach-Withdrawal, and Behavioral Inhibition System–Behavioral Activation System models. Observing the relative merits and limitations of these models, a new direction for exploration is offered. Specifically, to better appreciate the strength and direction (i.e., approach versus withdrawal) of experienced emotions, it is recommended that state “dominance” be evaluated in the context of asymmetrical activation of left-frontal (dominance) versus right-frontal (submission) brain regions.

Alexithymia in Parkinson's disease: A systematic review of the literature

INTRODUCTION

In this systematic review, we aimed to evaluate the role of alexithymia in Parkinson's disease (PD) and its relationship to neurological, neuropsychiatric, cognitive, and neuroimaging correlates.

METHODS

The database was selected using PubMed Services, Cochrane, PsycNET and Scopus and a number of key words. Further studies were sought by manually searching for secondary sources, including relevant journals and references in primary articles. The search was restricted to articles written in English between January 1980 and August 2015.

RESULTS

Ten studies reported that alexithymia prevalence was about double in PD patients compared to control subjects and that specific dimensions of alexithymia might be related to depression, anxiety, apathy and impulsivity. Some studies investigated the relationship between alexithymia and neuropsychological symptoms and found correlations with frontal and parietal lobe functions. Two studies on neurological features reported a link between alexithymia and disease stage or a specific motor subtype of PD; the remaining studies found that alexithymia was independent from neurological symptoms, dopaminergic therapy and laterality of motor symptom onset. Data on neuroimaging correlates and therapeutic intervention on alexithymia in PD patients are still lacking.

CONCLUSION

Although results suggest that alexithymia is a primary characteristics of PD, further studies with larger patient samples are needed to definitively clarify the impact of alexithymia on the clinical features of PD patients.

Quantitative analysis of Euclidean distance to complement qualitative analysis of facial expression during deception

BACKGROUND

Accurate evaluation of an individuals' veracity is a fundamental aspect of social functioning that allows individuals to act in adaptive ways. The domain of deception detection ability is still young, and many components in this field are yet to be touched which demands more research in this field.

AIMS

The present study aims at deciphering the structural composition of face during felt, posed, and deceived emotions in facial expression unique to Indian culture, using Facial Action Coding System (FACS). Quantitative analysis of Euclidean distance has been done to complement qualitative FACS analysis.

METHODS

In this study, thirty female, young adults with age range of 23-27 years were chosen randomly for portraying their (felt, posed, and deceived) facial expression. All facial expressions were captured through instruction, and videos were converted into static images. The static images were coded on the basis of FACS to decipher the felt, posed, and deceived expressions. Quantitative analysis of the data has been done using MATLAB to meet the objectives of the study and to complement the qualitative analysis.

RESULTS

Felt and posed emotions differ in terms of intensity of the expression and subjective experience. Posed emotional and deceived expressions differ in intent. Facial asymmetry is an important indicator for detecting deception.

Which Cheek did the Resurrected Jesus Turn?

Secular portraits are likely to show more of the left than right side of the face (hemiface). Prior research has shown that emotions are more strongly expressed by the left hemiface. In addition, the valence theory of emotion proposes that the right hemisphere is dominant for mediating negative emotions, and the left hemisphere for positive emotions. Since religious art depicting a scene such as the Resurrection of Jesus is more likely to be associated with positive emotions, we postulated that there would be a significant smaller percentage number of artistic works of the Resurrection that reveal the left side of the face of Jesus than in those art works portraying the Crucifixion. Thus, we analyzed artistic portrayals of the Resurrection of Jesus and compared them to the artistic scenes of the Crucifixion. This analysis revealed that the left side of the face of Jesus is less commonly depicted in portraits of the Resurrection than the Crucifixion. In addition, both the right hemiface, and forward-facing faces were also more commonly portrayed in painting of the Resurrection than the Crucifixion. Whereas this right-left hemiface, Resurrection-Crucifixion dichotomy may be related to right-left hemispheric difference in the mediation of emotional valence other factors such as agency, action-intention, and biblical text may have influenced these differences.

Impaired fear recognition and attentional set-shifting is associated with brain structural changes in alcoholic patients

Alcoholic patients with multiple detoxifications/relapses show cognitive and emotional deficits. We performed structural magnetic resonance imaging and examined performance on a cognitive flexibility task (intra-extradimensional set shift and reversal; IED). We also presented subjects with fearful, disgust and anger facial emotional expressions. Participants were abstaining, multiply detoxified (MDTx; n = 12) or singly detoxified patients (SDTx; n = 17) and social drinker controls (n = 31). Alcoholic patients were less able than controls to change their behavior in accordance with the changing of the rules in the IED and they were less accurate in recognizing fearful expressions in particular. They also showed lower gray matter volume compared with controls in frontal brain areas, including inferior frontal cortex (IFC) and insula that mediate emotional processing, inferior parietal lobule and medial frontal cortex that mediate attentional and motor planning processes, respectively. Impairments in performance and some of the regional decreases in gray matter were greater in MDTx. Gray matter volume in IFC in patients was negatively correlated with the number of detoxifications, whereas inferior parietal lobule was negatively correlated with the control over drinking score (impaired control over drinking questionnaire). Performance in IED was also negatively correlated with gray matter volume in IFC/BA47, whereas recognition of fearful faces was positively correlated with the IFC gray matter. Repeated episodes of detoxification from alcohol, related to severity of dependency, are coupled with altered brain structure in areas of emotional regulation, attention and motor planning. Such changes may confer increased inability to switch behavior according to environmental demands and social incompetence, contributing to relapse.

Asymmetry of the endogenous opioid system in the human anterior cingulate: a putative molecular basis for lateralization of emotions and pain

Lateralization of the processing of positive and negative emotions and pain suggests an asymmetric distribution of the neurotransmitter systems regulating these functions between the left and right brain hemispheres. By virtue of their ability to selectively mediate euphoria, dysphoria, and pain, the μ-, δ-, and κ-opioid receptors and their endogenous ligands may subserve these lateralized functions. We addressed this hypothesis by comparing the levels of the opioid receptors and peptides in the left and right anterior cingulate cortex (ACC), a key area for emotion and pain processing. Opioid mRNAs and peptides and 5 "classical" neurotransmitters were analyzed in postmortem tissues from 20 human subjects. Leu-enkephalin-Arg (LER) and Met-enkephalin-Arg-Phe, preferential δ-/μ- and κ-/μ-opioid agonists, demonstrated marked lateralization to the left and right ACC, respectively. Dynorphin B (Dyn B) strongly correlated with LER in the left, but not in the right ACC suggesting different mechanisms of the conversion of this κ-opioid agonist to δ-/μ-opioid ligand in the 2 hemispheres; in the right ACC, Dyn B may be cleaved by PACE4, a proprotein convertase regulating left-right asymmetry formation. These findings suggest that region-specific lateralization of neuronal networks expressing opioid peptides underlies in part lateralization of higher functions, including positive and negative emotions and pain in the human brain.

Excitability of motor cortices as a function of emotional sounds

We used transcranial magnetic stimulation (TMS) to clarify how non-verbal emotionally-characterized sounds modulate the excitability of the corticospinal motor tract (CST). While subjects were listening to sounds (monaurally and binaurally), single TMS pulses were delivered to either left or right primary motor cortex (M1), and electromyographic activities were recorded from the contralateral abductor pollicis brevis muscle. We found a significant increase in CST excitability in response to unpleasant as compared to neutral sounds. The increased excitability was lateralized as a function of stimulus valence: Unpleasant stimuli resulted in a significantly higher facilitation of motor potentials evoked in the left hemisphere, while pleasant stimuli yielded a greater CST excitability in the right one. Furthermore, TMS induced higher motor evoked potentials when listening to unpleasant sounds with the left than with the right ear. Taken together, our findings provide compelling evidence for an asymmetric modulation of CST excitability as a function of emotional sounds along with ear laterality.

Hemispheric interaction, task complexity, and emotional valence: evidence from naturalistic images

Two experiments extend the ecological validity of tests of hemispheric interaction in three novel ways. First, we present a broad class of naturalistic stimuli that have not yet been used in tests of hemispheric interaction. Second, we test whether probable differences in complexity within the class of stimuli are supported by outcomes from measures of hemispheric interaction. Third, we use a procedure that presents target stimuli at fixation rather than at a lateralized location in order to more closely approximate normal viewing behavior. Images of positive or negative valence were presented with a lateralized distractor or no distractor at all. Response time and accuracy to determine whether an image was pleasant or unpleasant was measured. Results found that positive images were more quickly and accurately processed by the left hemisphere alone, while negative images were more quickly processed when the hemispheres interacted, and were more accurately processed when the hemispheres interacted than the left hemisphere alone. The findings support the idea that hemispheric interaction costs the performance of a simple task and benefits the performance of a complex task, and that the respective cost or gain is mediated by the pattern of laterality for emotional processing.

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.

Recognition of emotion from facial expression following traumatic brain injury

PRIMARY OBJECTIVE

To assess three domains of emotion recognition in people with traumatic brain injury (TBI).

RESEARCH DESIGN

A between group comparison.

PROCEDURES

Twenty-four participants with severe TBI and 15 matched participants without brain damage were asked to label and match facial expressions with and without context. The participants with TBI were also interviewed regarding changes in subjective experience of emotion.

MAIN OUTCOMES AND RESULTS

Participants with TBI were found to be significantly impaired on expression labelling and matching, but experienced some improvement when provided with context. Negative emotions were particularly affected. Affective semantic knowledge and face perception appeared to be relatively intact in this group. The majority of participants with TBI reported some change in the post-injury experience of everyday emotion, although the pattern of changes differed greatly between individuals. Reduced subjective experience, especially of sadness and fear, was associated with poor emotion matching but not emotion labelling.

Perception and recall of faces and facial expressions following temporal lobectomy

The perception of and memory for faces, with or without emotional content, were studied in 43 patients with temporal lobe epilepsy who had undergone unilateral resection of the hippocampus and the amygdala and in 43 healthy participants for comparison. Each participant performed four tasks from the Florida Affect Battery (Facial Discrimination, Affect Discrimination, Affect Naming, Affect Selection) and two memory tasks (in one case of a face and in the other of a facial expression). Findings indicated that, although patients with unilateral temporal lobectomy (right or left) showed no difficulty in discriminating faces, they were not as good at remembering faces. Also, patients who had had a left temporal lobectomy showed impairment in discriminating facial expressions, in the memory of a facial expression and/or in naming facial expressions.

Cortical activation in alexithymia as a response to emotional stimuli

BACKGROUND

Alexithymia has been shown to be related to many psychiatric and somatic illnesses. Aberrant emotion processing in the brain may underlie several psychiatric disorders. However, little is known about the neurobiological underpinnings of alexithymia.

AIMS

To determine the way in which the brain processes emotion in alexithymia.

METHOD

The participants were 10 healthy women with alexithymia and 11 healthy women without this condition, recruited into the study on the basis of their scores on the 20-item Toronto Alexithymia Scale. Four films were projected on a video screen to induce each of three emotional conditions (neutral, amusement, sadness). The brain areas activated during emotional stimuli in the alexithymia group were compared with those activated in the non-alexithymia group. Scans of the distribution of [(15)O]H(2)O were acquired using a positron emission tomography (PET) scanner operated in three-dimensional mode.

RESULTS

In response to emotional stimuli participants with alexithymia activated more parts of their sensory and motor cortices and insula, especially on the left side, and less of their anterior cingulate, compared with the control group.

CONCLUSIONS

Women with alexithymia seem to over-activate their 'bodily' brain regions, implying a different mode of emotion processing. This may be related to their tendency to experience physical symptoms.

Neuropsychological correlates of alexithymia in Parkinson's disease

There are recent reports that alexithymia may be associated with brain dysfunction involving frontal lobes or right hemisphere regions. However, little is known about the relationship between alexithymia and cognitive deficits in Parkinson's disease (PD). The authors investigated the neuropsychological correlates of alexithymia in a population of 70 nondemented PD patients and 70 controls. Alexithymia was screened using the 20-item version of the Toronto Alexithymia Scale (TAS-20). Standardized scales that measure verbal episodic memory, executive functions, abstract reasoning, and visual-spatial and language abilities were adopted. PD patients with alexithymia performed worse than both PD patients without alexithymia and controls with or without alexithymia on tasks requiring visual-spatial processing. Moreover, regression analyses showed that, in PD patients, but not in controls, poor performance on a constructional praxis task predicted high scores on the TAS-20 subscale, which assesses difficulty in identifying emotions. These data evidence an association between alexithymia and visual-spatial processing alterations in PD patients, supporting the view that the right hemisphere could be specifically involved in the modulation of some facets of alexithymia.

Recognizing emotion from facial expressions: psychological and neurological mechanisms

Recognizing emotion from facial expressions draws on diverse psychological processes implemented in a large array of neural structures. Studies using evoked potentials, lesions, and functional imaging have begun to elucidate some of the mechanisms. Early perceptual processing of faces draws on cortices in occipital and temporal lobes that construct detailed representations from the configuration of facial features. Subsequent recognition requires a set of structures, including amygdala and orbitofrontal cortex, that links perceptual representations of the face to the generation of knowledge about the emotion signaled, a complex set of mechanisms using multiple strategies. Although recent studies have provided a wealth of detail regarding these mechanisms in the adult human brain, investigations are also being extended to nonhuman primates, to infants, and to patients with psychiatric disorders.

Neuropsychological correlates of organic alexithymia

Deficits in emotional recognition and perception following traumatic brain injury (TBI) have been associated with alexithymia (Henry et al., 2006; Williams et al., 2001). This study examined the prevalence of alexithymia in a TBI population, and its relationship to injury severity, neuropsychological ability and affective disorder. A total of 121 patients completed the Toronto Alexithymia Scale-20 (TAS-20), a measure that addresses 3 distinct characteristics of the alexithymia concept; difficulty identifying feelings, difficulty describing feelings, and externally oriented thinking. Patients also completed a neuropsychological assessment and measures of depression and anxiety. Results confirm a high prevalence of alexithymia after TBI, relative to the general population and an orthopedic control group. There was no relationship between injury severity and the presence of alexithymia. A negative relationship was found between alexithymia and verbal and sequencing abilities, but there was no relationship with executive dysfunction or any other cognitive domain. Moderate correlations were obtained between alexithymia and affective disorder; regression analyses indicated that alexithymia, depression, and anxiety should be considered distinct, but overlapping constructs. The results of this study suggest that increased neuropsychological attention should be directed towards emotional change after head injury and its relationship with cognition and psychosocial outcome.

Defective comprehension of emotional faces and prosody as a result of right hemisphere stroke: modality versus emotion-type specificity

Studies of patients with brain damage, as well as studies with normal subjects have revealed that the right hemisphere is important for recognizing emotions expressed by faces and prosody. It is unclear, however, if the knowledge needed to perform recognition of emotional stimuli is organized by modality or by the type of emotion. Thus, the purpose of this study is to assess these alternative a priori hypotheses. The participants of this study were 30 stroke patients with right hemisphere damage (RHD) and 31 normal controls (NC). Subjects were assessed with the Polish adaptation of the Right Hemisphere Language Battery of Bryan and the Facial Affect Recognition Test based on work of Ekman and Friesen. RHD participants were significantly impaired on both emotional tasks. Whereas on the visual-faces task the RHD subjects recognized happiness better than anger or sadness, the reverse dissociation was found in the auditory-prosody test. These results confirm prior studies demonstrating the role of the right hemisphere in understanding facial and prosodic emotional expressions. These results also suggest that the representations needed to recognize these emotional stimuli are organized by modality (prosodic-echoic and facial-eidetic) and that some modality specific features are more impaired than others.

The differential effects of thalamus and basal ganglia on facial emotion recognition

This study examined if subcortical stroke was associated with impaired facial emotion recognition. Furthermore, the lateralization of the impairment and the differential profiles of facial emotion recognition deficits with localized thalamic or basal ganglia damage were also studied. Thirty-eight patients with subcortical strokes and 19 matched normal controls volunteered to participate. The participants were individually presented with morphed photographs of facial emotion expressions over multiple trials. They were requested to classify each of these morphed photographs according to Ekman's six basic emotion categories. The findings indicated that the clinical participants had impaired facial emotion recognition, though no clear lateralization pattern of impairment was observed. The patients with localized thalamic damage performed significantly worse in recognizing sadness than the controls. Longitudinal studies on patients with subcortical brain damage should be conducted to examine how cognitive reorganization post-stroke would affect emotion recognition.

Differential effects of lesions of the amygdala and prefrontal cortex on recognizing facial expressions of complex emotions

Humans can detect facial expressions of both simple, basic emotions and expressions reflecting more complex states of mind. The latter includes emotional expressions that regulate social interactions ("social expressions" such as looking hostile or friendly) and expressions that reflect the inner thought state of others ("cognitive expressions" such as looking pensive). To explore the neural substrate of this skill, we examined performance on a test of detection of such complex expressions in patients with lesions of the temporal lobe (n = 54) or frontal lobe (n = 31). Of the temporal group, 18 had unilateral focal lesions of the amygdala and of the frontal group, 14 patients had unilateral lesions of the ventromedial prefrontal cortex-two regions held to be pivotal in mediating social cognitive skills. Damage to either the left or right amygdala was associated with impairment in the recognition of both social and cognitive expressions, despite an intact ability to extract information relating to invariant physical attributes. Lesions to all of the right prefrontal cortex-not just the ventromedial portions-led to a specific deficit in recognizing complex social expressions with a negative valence. The deficit in the group with right prefrontal cortical damage may contribute to the disturbances in social behavior associated with such lesions. The results also suggest that the amygdala has a role in processing a wide range of emotional expressions.

Left hemisphere specialization for response to positive emotional expressions: A divided output methodology

An extensive literature credits the right hemisphere with dominance for processing emotion. Conflicting literature finds left hemisphere dominance for positive emotions. This conflict may be resolved by attending to processing stage. A divided output (bimanual) reaction time paradigm in which response hand was varied for emotion (angry; happy) in Experiments 1 and 2 and for gender (male; female) in Experiment 3 focused on response to emotion rather than perception. In Experiments 1 and 2, reaction time was shorter when right-hand responses indicated a happy face and left-hand responses an angry face, as compared to reversed assignment. This dissociation did not obtain with incidental emotion (Experiment 3). Results support the view that response preparation to positive emotional stimuli is left lateralized.

Functional MRI of facial emotion recognition deficits in schizophrenia and their electrophysiological correlates

Empirical evidence suggests impaired facial emotion recognition in schizophrenia. However, the nature of this deficit is the subject of ongoing research. The current study tested the hypothesis that a generalized deficit at an early stage of face-specific processing (i.e. putatively subserved by the fusiform gyrus) accounts for impaired facial emotion recognition in schizophrenia as opposed to the Negative Emotion-specific Deficit Model, which suggests impaired facial information processing at subsequent stages. Event-related potentials (ERPs) were recorded from 11 schizophrenia patients and 15 matched controls while performing a gender discrimination and a facial emotion recognition task. Significant reduction of the face-specific vertex positive potential (VPP) at a peak latency of 165 ms was confirmed in schizophrenia subjects whereas their early visual processing, as indexed by P1, was found to be intact. Attenuated VPP was found to correlate with subsequent P3 amplitude reduction and to predict accuracy when performing a facial emotion discrimination task. A subset of ten schizophrenia patients and ten matched healthy control subjects also performed similar tasks in the magnetic resonance imaging scanner. Patients showed reduced blood oxygenation level-dependent (BOLD) activation in the fusiform, inferior frontal, middle temporal and middle occipital gyrus as well as in the amygdala. Correlation analyses revealed that VPP and the subsequent P 3a ERP components predict fusiform gyrus BOLD activation. These results suggest that problems in facial affect recognition in schizophrenia may represent flow-on effects of a generalized deficit in early visual processing.

What is said or how it is said makes a difference: role of the right fronto-parietal operculum in emotional prosody as revealed by repetitive TMS

Emotional signals in spoken language can be conveyed by semantic as well as prosodic cues. We investigated the role of the fronto-parietal operculum, a somatosensory area where the lips, tongue and jaw are represented, in the right hemisphere to detection of emotion in prosody vs. semantics. A total of 14 healthy volunteers participated in the present experiment, which involved transcranial magnetic stimulation (TMS) in combination with frameless stereotaxy. As predicted, compared with sham stimulation, TMS over the right fronto-parietal operculum differentially affected the reaction times for detection of emotional prosody vs. emotional semantics, showing that there is a dissociation at a neuroanatomical level. Detection of withdrawal emotions (fear and sadness) in prosody was delayed significantly by TMS. No effects of TMS were observed for approach emotions (happiness and anger). We propose that the right fronto-parietal operculum is not globally involved in emotion evaluation, but sensitive to specific forms of emotional discrimination and emotion types.

Emotion recognition in stroke patients with left and right hemispheric lesion: Results with a new instrument—the FEEL Test

The aim of this study was to investigate the effect of a stroke event on people's ability to recognize basic emotions. In particular, the hypothesis that right brain-damaged (RBD) patients would show less of emotion recognition ability compared with left brain-damaged (LBD) patients and healthy controls, was tested. To investigate this the FEEL Test (Facially Expressed Emotion Labeling) was used, a computer based psychometric test that assesses one's ability to recognize facially displayed basic emotions via a forced-choice paradigm. We examined 24 patients after a stroke event (13 RBD, 11 LBD) and compared them with a matched group of healthy controls (HC, n=29). Results showed that the stroke patients performed significantly worse in the FEEL Test than did HC (p<.001). This deficit was especially evident for negative emotions (fear, anger, sadness, and disgust). In contrast to other studies we did not find any significant differences between RBD and LBD patients in their ability to recognize emotions. These results indicate that a stroke event has a negative effect on the recognition of facially displayed emotions but suggest that this effect is apparently not dependent on the side of the brain damage.

Neural substrates of emotion as revealed by functional magnetic resonance imaging

OBJECTIVES

To examine the brain circuitry involved in emotional experience and determine whether the cerebral hemispheres are specialized for positive and negative emotional experience.

BACKGROUND

Recent research has provided a preliminary sketch of the neurologic underpinnings of emotional processing involving specialized contributions of limbic and cortical brain regions. Electrophysiologic, functional imaging, and Wada test data have suggested positive, approach-related emotions are associated with left cerebral hemisphere regions, whereas negative, withdrawal-related emotions appear to be more aligned with right hemisphere mechanisms.

METHOD

These emotional-neural associations were investigated using functional magnetic resonance imaging in 10 healthy controls with 20 positively and 20 negatively valenced pictures from the International Affective Picture System in a counterbalanced order. Pictures were viewed within a 1.5 Telsa scanner through computerized video goggles.

RESULTS

Emotional pictures resulted in significantly increased blood flow bilaterally in the mesial frontal lobe/anterior cingulate gyrus, dorsolateral frontal lobe, amygdala/anterior temporal regions, and cerebellum. Negative emotional pictures resulted in greater activation of the right hemisphere, and positive pictures caused greater activation of the left hemisphere.

CONCLUSIONS

Results are consistent with theories emphasizing the importance of circuitry linking subcortical structures with mesial temporal, anterior cingulate, and frontal lobe regions in emotion and with the valence model of emotion that posits lateralized cerebral specialization for positive and negative emotional experience.

The peculiarity of the right-hemisphere function in depression: solving the paradoxes

Depression is characterized by functional insufficiency of the right hemisphere combined with its physiological overactivation. This paradox can be solved in the frame of the general concept of brain laterality. According to the present assumption, the left hemisphere organizes any information in an unambiguous monosemantic context, and this process requires an additional activation of the brain cortex in order to restrict natural relationships between objects and events. On the contrary, the right hemisphere organizes any information in the polysemantic context based on the simultaneous capture of the numerous natural relationships between elements of information. In healthy creative subjects this process does not require additional physiological activation of the cortex. In depression the physiological overactivation of the right hemisphere reflects the unsuccessful effort to overcome its functional insufficiency.

Perception of emotions from faces and voices following unilateral brain damage

The importance of the right hemisphere in emotion perception in general has been well documented but its precise role is disputed. We compared the performance of 30 right hemisphere damaged (RHD) patients, 30 left hemisphere damaged (LHD) patients, and 50 healthy controls on both facial and vocal affect perception tasks of specific emotions. Brain damaged subjects had a single episode cerebrovascular accident localised to one hemisphere. The results showed that right hemisphere patients were markedly impaired relative to left hemisphere and healthy controls on test performance: labelling and recognition of facial expressions and recognition of emotions conveyed by prosody. This pertained at the level of individual basic emotions, positive versus negative, and emotional expressions in general. The impairment remained highly significant despite covarying for the group's poorer accuracy on a neutral facial perception test and identification of neutral vocal expressions. The LHD group were only impaired relative to controls on facial emotion tasks when their performance was summed over all the emotion categories and before age and other cognitive factors were taken into account. However, on the prosody test the LHD patients showed significant impairment, performing mid-way between the right hemisphere patients and healthy comparison group. Recognition of positive emotional expressions was better than negative in all subjects, and was not relatively poorer in the LHD patients. Recognition of individual emotions in one modality correlated weakly with recognition in another, in all three groups. These data confirm the primacy of the right hemisphere in processing all emotional expressions across modalities--both positive and negative--but suggest that left hemisphere emotion processing is modality specific. It is possible that the left hemisphere has a particular role in the perception of emotion conveyed through meaningful speech.

Cognitive and emotional characteristics of alexithymia: a review of neurobiological studies

OBJECTIVE

To review neurobiological studies of alexithymia in order to achieve a better understanding of the relationship between alexithymia and psychosomatic diseases and psychiatric illnesses.

METHODS

Neurobiological studies of alexithymia were reviewed with a special focus on how emotional and cognitive elements of alexithymia are reflected in earlier research.

RESULTS

Studies that have correlated alexithymia to corpus callosum dysfunctioning have mainly found impairments in cognitive characteristics of alexithymia, whereas from studies of right hemisphere and frontal lobe deficits, it may be concluded that both cognitive and emotional characteristics of alexithymia are impaired.

CONCLUSION

The fact that there is no general agreement on how to define alexithymia seems to have hampered theoretical and empirical progress on the neurobiology of alexithymia and related psychosomatic diseases and psychiatric illnesses. Alexithymia should no longer be approached as one distinct categorical phenomenon and follow-up studies should monitor subjects according to both the cognitive and emotional characteristics of alexithymia.

Differential susceptibility to performance degradation across categories of facial emotion--a model confirmation

Patients with a number of psychiatric and neuropathological conditions demonstrate problems in recognising facial expressions of emotion. Research indicating that patients with schizophrenia perform more poorly in the recognition of negative valence facial stimuli than positive valence stimuli has been interpreted as evidence of a negative emotion specific deficit. An alternate explanation rests in the psychometric properties of the stimulus materials. This model suggests that the pattern of impairment observed in schizophrenia may reflect initial discrepancies in task difficulty between stimulus categories, which are not apparent in healthy subjects because of ceiling effects. This hypothesis is tested, by examining the performance of healthy subjects in a facial emotion categorisation task with three levels of stimulus resolution. Results confirm the predictions of the model, showing that performance degrades differentially across emotion categories, with the greatest deterioration to negative valence stimuli. In the light of these results, a possible methodology for detecting emotion specific deficits in clinical samples is discussed.

Emotional processing deficits in individuals with unilateral brain damage

This article presents a review of the neural mechanisms underlying emotional processing deficits (EPDs) in individuals with unilateral brain damage. First, key theoretical issues pertaining to the neuropsychology of emotion are presented. These include parameters of emotional processing, the componential approach, emotional domains, and hypotheses regarding hemispheric specialization for emotion. Second, the literature on hemispheric asymmetries for emotion is reviewed in terms of processing mode (perception and expression) and communication channel (facial, prosodic-intonational, and lexical-verbal). Studies involving normal adults and individuals with right- or left-sided brain damage are reviewed. Third, recent findings identifying the role of the right hemisphere in emotional processing are described. The article is concluded by aligning these new data with findings from the general literature, providing added support for the right-hemisphere emotion hypothesis.

Perception of happy and sad facial expressions in chronic schizophrenia: evidence for two evaluative systems

BACKGROUND

Persons suffering from schizophrenia have impaired perception of emotional expressions, but it is not clear whether this is part of a generalized deficit in cognitive function.

AIM

To test for existence of emotion-specific deficits by studying the effects of valence on recognition of facial emotional expressions.

METHODS

24 male subjects suffering from chronic schizophrenia were examined with two tests of perception of emotion: the Penn Emotion Acuity Test (PEAT 40) and the Emotion Differentiation Task (EMODIFF). Clinical state was assessed with the Scale for the Assessment of Negative Symptoms (SANS) and Scale for the Assessment of Positive Symptoms (SAPS), visual memory with the Benton Visual Retention Test (BVRT) and motor function with the finger tapping test.

RESULTS

Identification of happy facial expressions showed significant negative correlation with age, cumulated time in hospital and length of current hospitalization; positive correlations were found with visual retention and finger tapping scores. Identification of sad facial expressions showed significant correlation only with cumulated time in hospital while identification of neutral facial expressions showed no significant correlations. Discrimination between degrees of happy but not sad facial expression showed a positive correlation with negative symptoms.

CONCLUSION

Perception of happy and sad emotion relates differently to significant illness parameters. This differentiability supports the existence of an emotion-specific deficit in perception of emotions in schizophrenia and of separate channels for processing positive and negative emotions.

A generalised deficit can account for problems in facial emotion recognition in schizophrenia

Neuroimaging research has shown localised brain activation to different facial expressions. This, along with the finding that schizophrenia patients perform poorly in their recognition of negative emotions, has raised the suggestion that patients display an emotion specific impairment. We propose that this asymmetry in performance reflects task difficulty gradations, rather than aberrant processing in neural pathways subserving recognition of specific emotions. A neural network model is presented, which classifies facial expressions on the basis of measurements derived from human faces. After training, the network showed an accuracy pattern closely resembling that of healthy subjects. Lesioning of the network led to an overall decrease in the network's discriminant capacity, with the greatest accuracy decrease to fear, disgust and anger stimuli. This implies that the differential pattern of impairment in schizophrenia patients can be explained without having to postulate impairment of specific processing modules for negative emotion recognition.

Perception of facial emotions in chronic schizophrenia does not correlate with negative symptoms but correlates with cognitive and motor dysfunction

BACKGROUND

Appropriate expression of emotions and correct perception of emotional expression in others are important social skills which may be impaired in schizophrenia and contribute to poor social adjustment. We examined the relationship between expression of emotions as measured by affective flattening and other negative symptoms and their perception. We compared performance on tests of perception of facial emotions with that in other cognitive areas.

METHODS

36 chronic schizophrenic patients on stable doses of atypical antipsychotics were assessed using tests of identification (FID) and discrimination (FDIS) of facial emotional expressions, visual retention (BVRT) and general cognitive function (Mini Mental State Examination, MMSE). Clinical symptoms were assessed with scales for the assessment of negative symptoms (SANS) and positive symptoms (SAPS). Motor symptoms were assessed with side effects (SA) and AIMS scales and Finger Tapping Test.

RESULTS

Negative symptoms showed no relation to FID or FDIS. FID showed significant correlation with Visual Retention and Finger Tapping but not MMSE.

CONCLUSION

The ability to identify facial emotional expressions is not related to negative symptoms in chronic schizophrenia and shares common mechanisms with visual reproduction and ability to make rapid motor movements. This suggests common defects in perceptual, timed processes consistent with postulated dysfunction of cortico-subcortical circuits.

Alexithymic features in stroke: effects of laterality and gender

OBJECTIVE

Stroke patients suffer from a high rate of behavioral disorders, and the laterality of the lesion may affect the expression of emotional disturbances. This study tested the hypothesis that stroke patients with a lesion in the right hemisphere are at high risk of developing alexithymic features.

METHODS

Forty-eight patients were interviewed with the Structured Clinical Interview for DSM-IV (patient edition), the Mini-Mental State Examination, the State-Trait Anxiety Inventory (state form), the Beck Depression Inventory, and the Toronto Alexithymia Scale (20-item version). Alexithymic differences between stroke patients with a lesion in the right hemisphere and those with a lesion in the left hemisphere were computed by analysis of covariance, using scores on the Mini-Mental State Examination, Beck Depression Inventory (psychic subscore), and State-Trait Anxiety Inventory as covariates and the score on the Toronto Alexithymia Scale as the dependent variable. A multivariate analysis of covariance and a series of follow-up analyses of covariance with the same covariates were used to discriminate differences in subscores on the Toronto Alexithymia Scale. An exploratory analysis of covariance was also performed to determine the effect of gender on alexithymic features in both groups of stroke patients.

RESULTS

The 21 stroke patients with a lesion in the right hemisphere were more alexithymic than the 27 patients with a lesion in the left hemisphere. This evidence was strengthened by the categorical analysis: 48% of the patients with a right-hemisphere lesion had alexithymia, compared with 22% of patients with a left-hemisphere lesion. Univariate analyses of covariance showed significant differences between the two groups in difficulty identifying feelings and difficulty describing feelings, but not in externally oriented thinking. The last exploratory analysis of covariance suggested that gender may influence alexithymic features.

CONCLUSIONS

This study provides direct evidence that alexithymia, and more specifically difficulty identifying feelings and difficulty describing feelings, is more common in stroke patients with a right-hemisphere lesion than in those with a left-hemisphere lesion. It also provides preliminary evidence that gender may affect alexithymic expression.

Sex-related differences in event-related potentials, face recognition, and facial affect processing in prepubertal children

Thirty-five prepubertal children, 17 boys and 18 girls, between the ages of 8 and 11 years, were studied to examine electrophysiological and cognitive sex differences during a face-recognition-memory (FRM) task and a facial-affect-identification task (FAIT). All participants were prepubertal, as determined by J. M. Tanner's (1962) staging and endocrine evaluation. Sex-dependent event-related potential (ERP) amplitude asymmetries were found during FRM. Boys displayed greater right versus left ERP amplitude to auditory tone probes during the task, whereas girls displayed the opposite pattern. In addition, positive correlations were obtained between ERP amplitude during FRM and FAIT accuracy scores for boys, but not for girls. Results suggest that girls and boys may use different neuronal systems in the processing of faces and facial affect. Findings are consistent with developmental theories regarding sex differences in visuospatial processing.