Corpus callosum damage to account for cognitive, affective, and social-cognitive dysfunctions in multiple sclerosis: A model of callosal disconnection syndrome?

The corpus callosum (CC) is the major commissure interconnecting the two hemispheres and is particularly affected in multiple sclerosis (MS). In the present review, we aimed to investigate the role played by callosal damages in the pathogenesis of MS-related dysfunctions and examine whether a model of callosal disconnection syndrome is a valid model for MS. For this purpose, we will first review structural and functional evidence of callosal pathology in MS. Second, we will account for the potential role of CC abnormalities in MS-related dysfunctions. Finally, we will report data concurring with a "multiple disconnection hypothesis" that has been proposed to explain those dysfunctions, and we will examine evidence pointing toward MS as a "callosal disconnection syndrome." We will end by discussing the contribution of this interpretation to the understanding of MS and MS-related deficits.

Attention orientation to pleasantness and depressive symptomatology predict autonomic reactivity.

Depression is characterised by attentional bias to emotional information and dysregulated autonomic reactivity. Despite its relevance to understanding depressive mechanisms, the association between attentional bias and autonomic reactivity to emotional information remains poorly characterised. This study compared behavioural and autonomic responses to emotional images in 32 participants in whom subclinical depressive symptomatology was quantified using the Beck Depression Inventory. Pairs of emotional and neutral images (unpleasant-neutral, U-N; pleasant-neutral, P-N; neutral-neutral, N-N) were presented while attentional indices (eye movements) and autonomic activity (skin conductance responses, SCRs; heart rate, HR) were recorded. Results showed that all recorded ocular parameters indicated a preferential orientation and maintenance of attention to emotional images. SCRs were associated with a valence effect on fixation latency: lower fixation latency to pleasant stimuli leads to lower SCRs whereas the opposite was observed for unpleasant stimuli. Finally, stepwise linear regression analysis revealed that latency of fixation to pleasant images and scores of depression predicted SCRs of participants. Thus, our research reveals an association between autonomic reactivity and attentional bias to pleasant information, on the one hand, and depressive symptomatology on the other. Present findings therefore suggest that depressive individuals may benefit from attention training towards pleasant information in association with autonomic biofeedback procedures.

How Do Self-Assessment of Alexithymia and Sensitivity to Bodily Sensations Relate to Alcohol Consumption?

BACKGROUND: Alexithymia describes an abnormality of emotional experience that is commonly expressed among individuals with addiction and alcohol abuse disorders. Alexithymic individuals are characterized by difficulties in identifying and describing their emotions. This impairment is linked to the development and maintenance of addiction. Moreover, an emergent theory suggests alexithymia is itself secondary to a failure of interoception (sensitivity to internal bodily signals, including physiological arousal states). METHODS: This study tested for hypothesized contributory roles of alexithymia and dysfunctional interoception in the expression of social drinking. Alexithymia, subjective sensitivity to bodily sensations, and alcohol consumption scores were quantified using the Toronto Alexithymia Scale, the Body Perception Questionnaire, and the Alcohol Use Questionnaire, respectively, in a normative sample (N = 600). Regression and bootstrapping mediation analyses were used to test the hypothesis that alexithymia mediated the association between sensitivity to bodily sensations and alcohol consumption. RESULTS: Alexithymia was positively correlated with sensitivity to bodily sensations and with alcohol consumption. Mediation analysis revealed that alexithymia, and more precisely, difficulty in identifying feelings, mediated the relationship between sensitivity to bodily sensations and alcohol consumption, such that the predictive effect of sensitivity to bodily sensations on alcohol intake became nonsignificant when controlling for alexithymia. CONCLUSIONS: These results indicate that alexithymia is associated with subjective hypersensitivity to bodily sensations. Moreover, our findings support the theoretical proposal that alexithymia is an expression of impaired processing of bodily sensations including physiological arousal, which underpin the development of maladaptive coping strategies, including alcohol use disorders. Our observations extend a growing literature emphasizing the importance of interoception and alexithymia in addiction, which can inform the development of new therapeutic strategies.

Arousal in response to neutral pictures is modified in temporal lobe epilepsy.

The objectives of the present study were to (i) better characterize visual emotional experience in patients with temporal lobe epilepsy (TLE), (ii) identify clinical risk factors that might be predictive of a change in emotional experience, and (iii) study the relationships between emotional experience and psychobehavioral/quality-of-life factors. Fifty patients with TLE and fifty matched controls evaluated the emotional content of unpleasant, pleasant, and neutral pictures with respect to their valence (unpleasant-to-pleasant) and arousal (low-to-high) levels. Demographic, cognitive, and psychobehavioral data were recorded for all participants, and clinical data and factors related to quality of life were also collected for patients with TLE. There were no significant differences between the group with TLE and the control group in terms of valence evaluations. However, arousal scores for neutral pictures were significantly higher in patients with TLE than in controls. There was also a nonsignificant trend towards lower arousal scores for pleasant pictures in patients with TLE than in controls. Although none of the recorded clinical factors were found to be related to emotional experience, the level of apathy was predictive of greater arousal experience for neutral pictures in patients with TLE. In conclusion, emotional experience appears to be modified in TLE and might be related to apathy. Changes in emotional experience should be taken into account in studies in which neutral stimuli are used to establish a baseline level when assessing emotional and cognitive processing.

The impact of attention bias modification training on behavioral and physiological responses.

Attention bias modification training aims to alter attentional deployment to symptom-relevant emotionally salient stimuli. Such training has therapeutic applications in the management of disorders including anxiety, depression, addiction and chronic pain. In emotional reactions, attentional biases interact with autonomically-mediated changes in bodily arousal putatively underpinning affective feeling states. Here we examined the impact of attention bias modification training on behavioral and autonomic reactivity. Fifty-eight participants were divided into two groups. A training group (TR) received attention bias modification training to enhance attention to pleasant visual information, while a control group (CT) performed a procedure that did not modify attentional bias. After training, participants performed an evaluation task in which pairs of emotional and neutral images (unpleasant-neutral, pleasant-neutral, neutral-neutral) were presented, while behavioral (eye movements) and autonomic (skin conductance; heart rate) responses were recorded. At the behavioral level, trained participants were faster to orientate attention to pleasant images, and slower to orientate to unpleasant images. At the autonomic level, trained participants showed attenuated skin conductance responses to unpleasant images, while stronger skin conductance responses were generally associated with higher anxiety. These data argue for the use of attentional training to address both the attentional and the physiological sides of emotional responses, appropriate for anxious and depressive symptomatology, characterized by atypical attentional deployment and autonomic reactivity.

Cooperative behavior in adolescents: a contribution of empathy and emotional regulation?

Aim: This study aims to identify different levels of empathy and emotional regulation along adolescent years and their relationship with cooperative behavior. Methods: Eighty healthy males were divided into four age groups: 20 Early Adolescents, 20 Middle Adolescents, 20 Late Adolescents and 20 Adults. Participants responded to empathic and emotional regulation scales, then were assigned to an unknown partner to perform the prisoner's dilemma paradigm. Results: The statistical analyses allowed to distinguish the groups on the basis of the components making up the two scales: scores on the Perspective Taking component were higher for Adults and Late Adolescents participants than for Middle Adolescents and Early Adolescents groups (p < 0.05); scores on the Personal Distress component were higher for Early Adolescents group than for Late Adolescents and Middle Adolescents groups (p < 0.05); scores on the Difficulties engaging in goal directed behavior component were higher for Middle Adolescents and Early Adolescents groups than for Adults group (p < 0.05). We observed differences between groups (p < 0.001) with higher number of cooperation responses in Adults compared to Middle Adolescents (p < 0.05) and Early Adolescents groups (p < 0.001). Discussion: These findings suggest that the cooperative behavior changes during the different stages of adolescence seem to be related to the development of empathy and emotional regulation components.

Correction: The psychological impact of the COVID-19 pandemic in Portugal: The role of personality traits and emotion regulation strategies.

[This corrects the article DOI: 10.1371/journal.pone.0269496.].

Sex differences in cognitive processing: An integrative review of electrophysiological findings.

Sex differences in cognition and their underlying brain mechanisms have attracted increasing attention. Brain electrical activity (EEG) represents a reliable, high-temporal resolution approach to assessing the neural correlates of ongoing cognitive activity. The aim of the present work was to provide a comprehensive review of the literature regarding sex differences in brain electrical activity during cognitive processing, and their potential relation to behavioral performance. The cognitive domains addressed are perception, attention, language, visuospatial reasoning, and the executive functions. Overall, the literature reviewed shows sex differences in brain electrical activity during cognitive processing. Differences were observed in such EEG characteristics as hemispheric specialization, scalp topography, amplitudes of event-related potential components, temporal dynamics, and connectivity patterns. While these between-sex differences varied across the cognitive domains analyzed, there were consistent results for visuospatial reasoning and language. Regarding the relationships between behavioral manifestations of cognitive functions and underlying brain dynamics, further research is required to draw reasonable conclusions, since many of the EEG studies reviewed did not assess behavioral differences. Future research must contemplate several confounding factors, such as the precise characteristics of the experimental tasks employed, the phases of the menstrual cycle, individual traits, subjective stimuli saliency, and the interaction of brain development with educational and sociocultural factors. Despite these concerns, the present review contributes to supporting a broad debate that aims to optimize cognitive and behavioral abilities in order to improve teaching strategies and learning skills and thus expand the potentialities of each sex.

The psychological impact of the COVID-19 pandemic in Portugal: The role of personality traits and emotion regulation strategies.

Recent evidence suggests that both personality traits (PT) and emotion regulation (ER) strategies play an important role in the way people cope with the COVID-19 pandemic. The aim of this study was two folded. First, to longitudinally investigate the psychological distress (depression, anxiety, and stress levels) taking in consideration PT and ER strategies in 3 different moments: during the first lockdown period (April/20), at the first deconfinement (May/20) and 1-month after the first deconfinement (Jun/20)-Experiment I. Second, to cross-sectionally evaluate the impact of the pandemic in psychological distress and the correlates with PT and ER 6-months after the first deconfinement November/20 to February/21 -Experiment II. A total of 722 volunteers (Experiment I = 180; Experiment II = 542) aged 18 years or older participated in this online survey. The findings from Experiment I show that psychological distress decreased after the lockdown period, however, neuroticism traits predicted higher levels of depression, anxiety and stress symptoms, while difficulties in ER strategies were identified as a risk factor for depression and stress. For experiment II, neuroticism traits and being infected with COVID-19 were associated to higher levels of symptomatology, while unemployment and the use of emotional suppression strategies to cope with emotional situations were associated to depressive and anxiety symptoms. Although the psychological impact of the COVID-19 outbreak decreased over time in our sample, the current findings suggest that difficulties in emotional regulation and high levels of neuroticism traits might be potential risk factors for psychiatric symptomatology during the COVID-19 pandemic. Thus, people with difficulties in ER and neuroticism traits would benefit from psychological interventions that provide personality-appropriate support and promote emotion regulation skills during stressful events, such as the case of the global pandemic.

Telling functional networks apart using ranked network features stability.

Over the past few years, it has become standard to describe brain anatomical and functional organisation in terms of complex networks, wherein single brain regions or modules and their connections are respectively identified with network nodes and the links connecting them. Often, the goal of a given study is not that of modelling brain activity but, more basically, to discriminate between experimental conditions or populations, thus to find a way to compute differences between them. This in turn involves two important aspects: defining discriminative features and quantifying differences between them. Here we show that the ranked dynamical stability of network features, from links or nodes to higher-level network properties, discriminates well between healthy brain activity and various pathological conditions. These easily computable properties, which constitute local but topographically aspecific aspects of brain activity, greatly simplify inter-network comparisons and spare the need for network pruning. Our results are discussed in terms of microstate stability. Some implications for functional brain activity are discussed.

Autonomic reactivity to emotion: A marker of sub-clinical anxiety and depression symptoms?

Anxiety and depression are both characterized by dysregulated autonomic reactivity to emotion. However, most experiments until now have focused on autonomic reactivity to stimuli presented in central vision (CV) even if affective saliency is also observed in peripheral vision (PV). We compared autonomic reactivity to CV and PV emotional stimulation in 58 participants with high anxious (HA) or low anxious (LA) and high depressive (HD) or low depressive (LD) symptomatology, based on STAI-B and BDI scores, respectively. Unpleasant (U), pleasant (P), and neutral (N) pictures from IAPS were presented at three eccentricities (0°: CV; -12 and 12°: PV). Skin conductance (SC), skin temperature, pupillary diameter, and heart rate (HR) were recorded. First, HA participants showed greater pupil dilation to emotional than to neutral stimuli in PV than in CV. Second, in contrast to HD, the valence effect indexed by SC and emotional arousal effect indexed by skin temperature were observed in LD. Third, both anxiety and depression lead to a valence effect indexed by pupillary light reflex and heart rate. These results suggest a hyperreactivity to emotion and hypervigilance to PV in anxiety. Depression is associated with an attenuation of positive effect and a global blunted autonomic reactivity to emotion. Moreover, anxiety mostly modulates the early processes of autonomic reactivity whereas depression mainly affects the later processes. The differential impact of emotional information over the visual field suggests the use of new stimulation strategies in order to attenuate anxious and depressive symptoms.

The Influence of Empathy Trait and Gender on Empathic Responses. A Study With Dynamic Emotional Stimulus and Eye Movement Recordings.

Previous studies have suggested that empathic process involve several components such as cognitive empathy, affective empathy, and prosocial concern. It has also been reported that gender and empathy trait can influence empathic responses such as emotional recognition, which requires an appropriate scanning of faces. However, the degree to which these factors influence the empathic responses, which include emotion recognition, affective empathy, and cognitive empathy, has not yet been specified. Aim: The aim of the present study was to identify the differences between individuals with high and low level of empathy trait, as well as differences between men and women, in an explicit task in order to evaluate the empathic responses. Methods: With this goal in mind, we recorded eye movements during the presentation of dynamic emotional stimuli (joy, anger, fear, and neutral videos). After watching each video, participants had to rate the valence and arousal dimensions of emotional content and explicit empathy responses were assessed. Thirty participants (15 women) were included in a High Empathy group (HE; mean age = 21.0) and 30 participants (16 women) in the Low Empathy group (LE; mean age = 21.2), according to their scores in the Interpersonal Reactivity Index (IRI) scale. Results: As expected, the HE group showed higher scores than the LE group in the explicit empathy responses. These differences, based on global scores, were mainly explained by affective empathy and cognitive empathy responses but not by emotional recognition one. No differences were observed by gender in these measures. Regarding eye movements in the dynamic emotional stimuli, HE group had longer fixation duration on the eyes area than LE group. In addition, women spent more time on the eyes area in comparison to men. Discussion: Our findings suggest that both men and women with high empathy trait are more accurate to empathizing but not on the basis of the emotional recognition response. The fact that women spent more time on the eyes area did not seem to affect the empathic responses to the dynamic emotional stimulus. Overall, empathic responses of both men and women are modulated by their empathic trait. In addition, empathic trait and gender seem to impact strategies to deal with emotional facial information.

Depression restricts visual capture and promotes the perception of negative information.

Emotional deficits in major depressive disorder lead to changes in the distribution of attention in the visual field. We investigate the impact of unpleasant and neutral pictures, presented in central (0°) and peripheral vision (12°; 24°), in 15 depression patients (DP) and 15 matched healthy controls (HC). Heart rate, skin conductance responses (SCRs) and electroencephalogram (EEG) were recorded. A spatiotemporal principal component analysis (PCA) was applied to the EEG, and ANCOVAs controlling for participants' state- and trait-anxiety and patients' medication were performed to assess the effects of visual eccentricity and emotion. Unlike HC, DP showed for CV stimulation 1/ greater sensitivity with a response bias toward unpleasant pictures, 2/ larger SCRs, especially to unpleasant pictures, and 3/ deeper cardiac deceleration. Furthermore, eccentricity and emotion modulated cerebral components. Finally, results bring a new vista on visual capture of negative information and support methods to enlarge the attentional span of depressed patients.

Electrical autonomic correlates of emotion.

This paper focussed on how electrophysiological autonomic data may contribute to better understand neural substrates of emotional processing. The utility of autonomic electrophysiological markers for assessing emotional and cognitive processes is presented in the context of an important bodily arousal interface. Components of general autonomic control are reviewed and relevant neural modulations of specific autonomic variables were discussed. The role of autonomic feedback on central processes is emphasized and neural influences on autonomic activities as an index of arousal dimension, the electrodermal activity (EDA), are outlined. An overview of brain mechanisms governing generation and control of EDA is presented, and the contribution of electrodermal parameters as indices of emotional activation illustrated by data related to diurnal emotional reactivity and to non consciously subjective emotionality. Conclusions highlight the role of electrical autonomic expressions as tools to explore emotional components of mind-body-mind relationships.

Signatures of alcohol use in the structure and neurochemistry of insular cortex: a correlational study.

RATIONALE: Insular cortex supports the representation of motivational feelings through the integration of interoceptive information concerning bodily physiology. Compromised insular integrity is implicated in alcohol and drug use disorders. Alcohol-associated insular dysfunction may arise through aberrant glutamatergic neurotransmission associated with selective neuronal death and atrophy. OBJECTIVE: In a sample of alcohol users, we combined magnetic resonance spectroscopy (MRS) with voxel and surface-based morphometry (VBM, SBM) to test the hypothesis that the neurochemical and structural properties of the insula relate to alcohol use. METHODS: Twenty-three healthy individuals were characterized by measures of alcohol use and subjective craving. Right mid-insula glutamate/glutamine (Glx) and total N-acetylaspartate/N-acetyl-aspartylglutamate (TNAA) concentrations were measured using MRS. Right insular structure was quantified using VBM and SBM parameters. We tested for predictive associations between these neuroimaging and behavioral/psychometric measures using Bayesian statistics. RESULTS: Reduced insular Glx concentration was associated with increased alcohol compulsions and, to a lesser extent, with greater alcohol use severity. Anecdotal evidence for a negative relationship between alcohol use severity and levels of insular gyrification was also observed. CONCLUSIONS: This study is, to date, the first characterization of the neurochemical and morphological integrity of insular cortex in alcohol users. Our data seem to reveal a negative relationship between alcohol use and the neurochemical and structural integrity of the insula, a critical substrate for motivational behavior. These neurobiological characteristics might contribute to loss of control toward compulsive drinking with prolonged and excessive alcohol use.

Affective picture processing: an integrative review of ERP findings.

The review summarizes and integrates findings from 40 years of event-related potential (ERP) studies using pictures that differ in valence (unpleasant-to-pleasant) and arousal (low-to-high) and that are used to elicit emotional processing. Affective stimulus factors primarily modulate ERP component amplitude, with little change in peak latency observed. Arousal effects are consistently obtained, and generally occur at longer latencies. Valence effects are inconsistently reported at several latency ranges, including very early components. Some affective ERP modulations vary with recording methodology, stimulus factors, as well as task-relevance and emotional state. Affective ERPs have been linked theoretically to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced stimulus processing has been associated with memory encoding for arousing pictures of assumed intrinsic motivational relevance, with task-induced differences contributing to emotional reactivity at later components (>300 ms). Theoretical issues, stimulus factors, task demands, and individual differences are discussed.

Impact of intranasal oxytocin on interoceptive accuracy in alcohol users: an attentional mechanism?

Interoception, i.e. the perception and appraisal of internal bodily signals, is related to the phenomenon of craving, and is reportedly disrupted in alcohol use disorders. The hormone oxytocin influences afferent transmission of bodily signals and, through its potential modulation of craving, is proposed as a possible treatment for alcohol use disorders. However, oxytocin's impact on interoception in alcohol users remains unknown. Healthy alcohol users (n = 32) attended two laboratory sessions to perform tests of interoceptive ability (heartbeat tracking: attending to internal signals and, heartbeat discrimination: integrating internal and external signals) after intranasal administration of oxytocin or placebo. Effects of interoceptive accuracy, oxytocin administration and alcohol intake, were tested using mixed-effects models. On the tracking task, oxytocin reduced interoceptive accuracy, but did not interact with alcohol consumption. On the discrimination task, we found an interaction between oxytocin administration and alcohol intake: Oxytocin, compared with placebo, increased interoceptive accuracy in heavy drinkers, but not in light social drinkers. Our study does not suggest a pure interoceptive impairment in alcohol users but instead potentially highlights reduced flexibility of internal and external attentional resource allocation. Importantly, this impairment seems to be mitigated by oxytocin. This attentional hypothesis needs to be explicitly tested in future research.

Autonomic Reactivity to Arousing Stimuli with Social and Non-social Relevance in Alexithymia.

Emotional difficulties in alexithymia and their social consequences have been linked to alterations in autonomic nervous system. However, most of previous studies did not take into account the distinction between the affective and the cognitive dimensions of the alexithymia, leading to inconsistent results. Aim: In this study, we compared the effects of both dimensions of alexithymia on the autonomic arousal to emotional and social visual stimulations. Methods: Skin conductance responses (SCRs) to items of the International Affective Pictures System characterized by emotional (unpleasant, neutral, and pleasant), social (with humans) or non-social (without humans) content were recorded in non-alexithymic (NA), affective (AA) and cognitive alexithymic (CA) participants, selected on the basis of the Toronto Alexithymia Scale and the Bermond-Vorst Alexithymia Questionnaire. All participants responded to questionnaires of empathy, social phobia, depression, and anxiety before the experiment and evaluated the arousal of the pictures after it. Results: Cognitive alexithymic group showed lower amplitudes of SCRs to pictures with social than without social relevance whereas the opposite pattern was observed for the NA group. Arousal emotional effects of the pictures on SCRs did not differ among groups. In addition, CA participants showed lower scores than NA in the Personal Taking sub-scale of the empathy questionnaire, while AA showed lower scores than NA in the fantasy sub-scale. The CA group showed higher social phobia, depression and anxiety scores, than the other two groups. Conclusion: This work has two original outcomes: first, affective alexithymics expressed lower empathic affective scores than other groups; second, alexithymia modulated the impact of the social relevance of the stimuli on the autonomic reactivity, this impact vanishing in affective alexithymics and reversing in cognitive alexithymics. Thus, though the groups could not be distinguished on the basis of emotional effect on SCRs, they clearly differed when the empathic characteristics and the autonomic impact of social relevance were considered. Finally, the described autonomic signature to social relevant information could contribute to elucidate the difficulty of alexithymics to deal with emotions during social transactions.

Facial thermal variations: A new marker of emotional arousal.

Functional infrared thermal imaging (fITI) is considered a promising method to measure emotional autonomic responses through facial cutaneous thermal variations. However, the facial thermal response to emotions still needs to be investigated within the framework of the dimensional approach to emotions. The main aim of this study was to assess how the facial thermal variations index the emotional arousal and valence dimensions of visual stimuli. Twenty-four participants were presented with three groups of standardized emotional pictures (unpleasant, neutral and pleasant) from the International Affective Picture System. Facial temperature was recorded at the nose tip, an important region of interest for facial thermal variations, and compared to electrodermal responses, a robust index of emotional arousal. Both types of responses were also compared to subjective ratings of pictures. An emotional arousal effect was found on the amplitude and latency of thermal responses and on the amplitude and frequency of electrodermal responses. The participants showed greater thermal and dermal responses to emotional than to neutral pictures with no difference between pleasant and unpleasant ones. Thermal responses correlated and the dermal ones tended to correlate with subjective ratings. Finally, in the emotional conditions compared to the neutral one, the frequency of simultaneous thermal and dermal responses increased while both thermal or dermal isolated responses decreased. Overall, this study brings convergent arguments to consider fITI as a promising method reflecting the arousal dimension of emotional stimulation and, consequently, as a credible alternative to the classical recording of electrodermal activity. The present research provides an original way to unveil autonomic implication in emotional processes and opens new perspectives to measure them in touchless conditions.

An ERP investigation of emotional processing in European and Japanese individuals.

This article examined neural time course differences in the processing of emotional pictures in European and Asian individuals. Event-related potentials (ERPs) were recorded in 15 French and 15 Japanese volunteers during the presentation of neutral and emotional pictures in their own country. ERPs were analyzed by means of spatio-temporal Principal Component Analysis (PCA) and allow to evaluate cultural influences on emotional processing along three temporal windows: 105 to 140 ms, 176 to 230 ms and 255 to 455 ms. Main results highlight that (1) early ERP components coded emotional charge but were not modulated by cultural background, (2) later components showed a significant decrease of amplitudes at parieto-occipital areas for Japanese participants compared to French ones in emotional condition. These findings suggest that, in both populations, similar neurocognitive processes are involved in the early stage of the emotional stimuli processing and effects observed on later components may reflect a poorer engagement of parietal areas, known to be involved in emotional arousal dimension. Considering that cognitive judgments were similar in both populations, electrophysiological findings suggest that cultural influences on later stage of emotional processing could be related to the known lower level of emotionally expressive behavior in Japanese than in Caucasians.