Early Career Award. Clarifying the emotive functions of asymmetrical frontal cortical activity

Positive affect versus reward: emotional and motivational influences on cognitive control

It is becoming increasingly appreciated that affective influences can contribute strongly to goal-oriented cognition and behavior. However, much work is still needed to properly characterize these influences and the mechanisms by which they contribute to cognitive processing. An important question concerns the nature of emotional manipulations (i.e., direct induction of affectively valenced subjective experience) versus motivational manipulations (e.g., delivery of performance-contingent rewards and punishments) and their impact on cognitive control. Empirical evidence suggests that both kinds of manipulations can influence cognitive control in a systematic fashion, but investigations of both have largely been conducted independently of one another. Likewise, some theoretical accounts suggest that emotion and motivation may modulate cognitive control via common neural mechanisms, while others suggest the possibility of dissociable influences. Here, we provide an analysis and synthesis of these various accounts, suggesting potentially fruitful new research directions to test competing hypotheses.

The right side? Under time pressure, approach motivation leads to right-oriented bias

Approach motivation, a focus on achieving positive outcomes, is related to relative left-hemispheric brain activation, which translates to a variety of right-oriented behavioral biases. In two studies, we found that approach-motivated individuals display a right-oriented bias, but only when they are forced to act quickly. In a task in which they had to divide lines into two equal parts, approach-motivated individuals bisected the line at a point farther to the right than avoidance-motivated individuals did, but only when they worked under high time pressure. In our analysis of all Fédération Internationale de Football Association (FIFA) World Cup penalty shoot-outs, we found that goalkeepers were two times more likely to dive to the right than to the left when their team was behind, a situation that we conjecture induces approach motivation. Because penalty takers shot toward the two sides of the goal equally often, the goalkeepers' right-oriented bias was dysfunctional, allowing more goals to be scored. Directional biases may facilitate group coordination but prove maladaptive in individual settings and interpersonal competition.

Cognitive vulnerability and frontal brain asymmetry: common predictors of first prospective depressive episode

The hopelessness theory of depression proposes that individuals with a depressogenic cognitive style are more likely to become hopeless and experience depression following negative life events. Although the neurophysiological underpinnings of cognitive style remain speculative, research indicates that decreased relative left frontal brain electrical activity holds promise as a traitlike marker of depression. This begs the question: Do measures of depressogenic cognitive style and resting frontal brain asymmetry index a common vulnerability? The present study provides preliminary support for this hypothesis. At baseline assessment, increased cognitive vulnerability to depression was associated with decreased relative left frontal brain activity at rest in individuals with no prior history of, or current, depression. Following baseline assessment, participants were followed prospectively an average of 3 years with structured diagnostic interviews at 4-month intervals. Both cognitive vulnerability and asymmetric frontal cortical activity prospectively predicted onset of first depressive episode in separate univariate analyses. Furthermore, multivariate analyses indicated that cognitive vulnerability and frontal asymmetry represented shared, rather than independent, predictors of first depression onset.

Anger and the speed of full-body approach and avoidance reactions

The notion that anger is linked to approach motivation received support from behavioral studies, which measured various motor responses to angering stimuli. However, none of these studies examined full-body motions which characterize many if not most everyday instances of anger. The authors incorporate a novel behavioral motor task that tests motivational direction by measuring the reaction times (RTs) of stepping forward and backward in response to the words “toward” and “away.” The results show that, relative to anxiety and control conditions, anger induction resulted in a steeper approach–avoidance RT gradient which was shifted in favor of approach.

Hemispheric processing of differently valenced and self-relevant attachment words in middle-aged married and separated individuals

The reliance in experimental psychology on testing undergraduate populations with relatively little life experience, and/or ambiguously valenced stimuli with varying degrees of self-relevance, may have contributed to inconsistent findings in the literature on the valence hypothesis. To control for these potential limitations, the current study assessed lateralised lexical decisions for positive and negative attachment words in 40 middle-aged male and female participants. Self-relevance was manipulated in two ways: by testing currently married compared with previously married individuals and by assessing self-relevance ratings individually for each word. Results replicated a left hemisphere advantage for lexical decisions and a processing advantage of emotional over neutral words but did not support the valence hypothesis. Positive attachment words yielded a processing advantage over neutral words in the right hemisphere, while emotional words (irrespective of valence) yielded a processing advantage over neutral words in the left hemisphere. Both self-relevance manipulations were unrelated to lateralised performance. The role of participant sex and age in emotion processing are discussed as potential modulators of the present findings.

Gender differences in emotional risk for self- and other-directed violence among externalizing adults

OBJECTIVE

Women and men generally differ in how frequently they engage in other- and self-directed physical violence and may show distinct emotional risk factors for engagement in these high-impact behaviors. To inform this area, we investigated gender differences in the relationship of emotional tendencies (i.e., anger, hostility, and anhedonic depression) that may represent risk for other-directed violence (i.e., physical fighting, attacking others unprovoked) and self-directed violence (i.e., self-injury, suicide attempts).

METHOD

The ethnically diverse sample consisted of 372 adults (252 men and 120 women age 18-55) with a history of criminal convictions. Facets of emotional risk assessed with the Aggression Questionnaire (Buss & Warren, 2000) and Mood and Anxiety Symptom Questionnaire (Watson et al., 1995) were entered simultaneously as explanatory variables in regression analyses to investigate their unique contributions to other- and self-directed physical violence in men and women.

RESULTS

Analyses revealed that anhedonic depressive tendencies negatively predicted other-directed violence and positively predicted self-directed violence in men and women, consistent with a model of depression in which aggression is turned inward (Henriksson et al., 1993). Gender differences, however, emerged for the differential contributions of anger and hostility to other- and self-directed violence. Trait anger (i.e., difficulty controlling one's temper) was associated with other-directed violence selectively in men, whereas trait hostility (i.e., suspiciousness and alienation) was associated with self- and other-directed violence among women.

CONCLUSIONS

The divergent findings for trait anger and hostility underscore the need to examine gender-specific risk factors for physical violence to avoid excluding potentially useful clinical features of these mental health outcomes.

The sad, the angry, and the asymmetrical brain: dichotic listening studies of negative affect and depression

Dichotic Listening (DL) is a valuable tool to study emotional brain lateralization. Regarding the perception of sadness and anger through affective prosody, the main finding has been a left ear advantage (LEA) for the sad but contradictory data for the anger prosody. Regarding an induced mood in the laboratory, its consequences upon DL were a diminished right ear advantage (REA) for the induction of sadness and an increased REA for the induction of anger. The global results fit with the approach-withdrawal motivational model of emotional processing, pointing to sadness as a right hemisphere emotion but anger processed bilaterally or even in the left hemisphere, depending on the subject's preferred mode of expression. On the other hand, the study of DL in clinically depressed patients found an abnormally larger REA in verbal DL tasks which was predictive of therapeutic pharmacological response. However, the mobilization of the available left hemisphere resources in these responders (reflected in a higher REA) would indicate a remission of the episode but would not assure the absence of new relapses.

Asymmetry in resting intracortical activity as a buffer to social threat

Social rejection can create powerful changes in people's brains and bodies. In the study reported here, we examined brain-based individual differences associated with buffering against cardiovascular threat responses to social rejection. Using EEG source-localization techniques, we examined differences in intracortical asymmetry. We predicted that individuals with greater left relative to right dorsolateral prefrontal activity would show a more approach-motivated response to social rejection. Eighty-four female participants were randomly assigned to one of three stressful situations: social rejection, social evaluation without rejection, or self-evaluation. Among participants assigned to the social-rejection condition, greater left relative to right prefrontal intracortical activity at baseline was associated with more adaptive cardiovascular profiles and more self-reported approach-oriented emotions. Participants in the other conditions did not show these relationships. Our data are the first to show that social context matters when attempting to link individual differences in cortical asymmetry with approach-related cardiovascular and emotional outcomes.

Social status determines how we monitor and evaluate our performance

Since people with low status are more likely to experience social evaluative threat and are therefore more inclined to monitor for these threats and inhibit approach behaviour, we expected that low-status subjects would be more engaged in evaluating their own performance, compared with high-status subjects. We created a highly salient social hierarchy based on the performance of a simple time estimation task. Subjects could achieve high, middle or low status while performing this task simultaneously with other two players who were either higher or lower in status. Subjects received feedback on their own performance, as well as on the performance of the other two players simultaneously. Electroencephalography (EEG) was recorded from all three participants. The results showed that medial frontal negativity (an event-related potential reflecting performance evaluation) was significantly enhanced for low-status subjects. Implications for status-related differences in goal-directed behaviour are discussed.

The Effect of Commitment on Relative Left Frontal Cortical Activity: Tests of the Action-Based Model of Dissonance

The action-based model of dissonance and recent advances in neuroscience suggest that commitment to action should cause greater relative left frontal cortical activity. Two experiments were conducted in which electroencephalographic activity was recorded following commitment to action, operationalized with a perceived choice manipulation. Perceived high as compared to low choice to engage in the action, regardless of whether it was counterattitudinal or proattitudinal, caused greater relative left frontal cortical activity. Moreover, perceived high as compared to low choice caused attitudes to be more consistent with the action. These results broaden the theoretical reach of the action-based model by suggesting that similar neural and motivational processes are involved in attitudinal responses to counterattitudinal and proattitudinal commitments.

Individualized alpha activity and frontal asymmetry in major depression

Lateralized differences in frontal alpha power in individuals with major depressive disorder (MDD) are thought to reflect an aberrant affective processing style. However research into anterior alpha asymmetry and MDD has often produced conflicting results. The current study aimed to investigate whether individualized alpha bandwidths provide a more sensitive measure of anterior alpha asymmetry in MDD than the traditional fixed 8-13 Hz alpha band. Resting EEG was recorded from 34 right-handed female participants (18 controls, 16 MDD). Each participant's Individual Alpha Frequency was used to delineate a broad individualized alpha band and three individualized narrow alpha sub-bands: lower alpha1, lower alpha 2 and upper alpha. Activity within the broad and narrow individualized bandwidths and within the traditional fixed alpha band were used to compare a) controls and acutely depressed individuals and b) medicated and unmedicated MDD participants. Individualizing and subdividing the alpha bandwidth did not add appreciably to the sensitivity of anterior alpha asymmetry in MDD as no significant differences in lateralized alpha power between controls and MDD participants were observed in any alpha bandwidth. This finding was consistent under two reference schemes and across multiple scalp locations. Within the MDD group, antidepressant use was associated with significantly greater right than left hemispheric power in the lower alpha 1 band. The relevance of this finding is discussed in relation to the electrophysiological correlates of antidepressant medication use, lateralized differences in affective processing and treatment resistant MDD.

Coordinated Roles of Motivation and Perception in the Regulation of Intergroup Responses: Frontal Cortical Asymmetry Effects on the P2 Event-related Potential and Behavior

Self-regulation is believed to involve changes in motivation and perception that function to promote goal-driven behavior. However, little is known about the way these processes interact during the on-line engagement of self-regulation. The present study examined the coordination of motivation, perception, and action control in White American participants as they regulated responses on a racial stereotyping task. Electroencephalographic indices of approach motivation (left frontal cortical asymmetry) and perceptual attention to Black versus White faces (the P2 event-related potential) were assessed during task performance. Action control was modeled from task behavior using the process-dissociation procedure. A pattern of moderated mediation emerged, such that stronger left frontal activity predicted larger P2 responses to race, which in turn predicted better action control, especially for participants holding positive racial attitudes. Results supported the hypothesis that motivation tunes perception to facilitate goal-directed action. Implications for theoretical models of intergroup response regulation, the P2 component, and the relation between motivation and perception are discussed.

Quantitative review of the efficacy of slow-frequency magnetic brain stimulation in major depressive disorder

BACKGROUND

Slow-frequency repetitive transcranial magnetic stimulation (rTMS) to the frontal cortex has been suggested as a safer and better tolerable alternative to fast-frequency rTMS in the treatment of major depressive disorder (MDD). The aim of the present study was to examine the efficacy of slow-frequency rTMS to the frontal cortex in MDD.

METHOD

A literature search was carried out in the databases PubMed and Web of Science in the period between January 1994 and July 2009 with the search terms 'depression' and 'transcranial magnetic stimulation'. Nine double-blind sham-controlled parallel intention-to-treat studies (252 patients) fulfilled inclusion criteria and were entered in a random-effects meta-analysis.

RESULTS

The test for heterogeneity was not significant (QT=9.63, p=0.38). An overall weighted moderate mean effect size (d=0.63, 95% confidence interval=0.03-1.24) for active treatment was observed.

CONCLUSIONS

The findings suggest that slow-frequency rTMS to the frontal cortex is more effective than sham treatment and may be equally effective as fast-frequency rTMS in the treatment of MDD.

The detection of communicative signals directed at the self in infant prefrontal cortex

A precondition for successful communication between people is the detection of signals indicating the intention to communicate, such as eye contact or calling a person's name. In adults, establishing communication by eye contact or calling a person's name results in overlapping activity in right prefrontal cortex, suggesting that, regardless of modality, the intention to communicate is detected by the same brain region. We measured prefrontal cortex responses in 5-month-olds using near-infrared spectroscopy (NIRS) to examine the neural basis of detecting communicative signals across modalities in early development. Infants watched human faces that either signaled eye contact or directed their gaze away from the infant, and they also listened to voices that addressed them with their own name or another name. The results revealed that infants recruit adjacent but non-overlapping regions in the left dorsal prefrontal cortex when they process eye contact and own name. Moreover, infants that responded sensitively to eye contact in the one prefrontal region were also more likely to respond sensitively to their own name in the adjacent prefrontal region as revealed in a correlation analysis, suggesting that responding to communicative signals in these two regions might be functionally related. These NIRS results suggest that infants selectively process and attend to communicative signals directed at them. However, unlike adults, infants do not seem to recruit a common prefrontal region when processing communicative signals of different modalities. The implications of these findings for our understanding of infants’ developing communicative abilities are discussed.

Valence specific laterality effects in free viewing conditions: the role of expectancy and gender of image

Recent research has looked at whether the expectancy of an emotion can account for subsequent valence specific laterality effects of prosodic emotion, though no research has examined this effect for facial emotion. In the study here (n=58), we investigated this issue using two tasks; an emotional face perception task and a novel word task that involved categorising positive and negative words. In the face perception task a valence specific laterality effect was found for surprise (positive) and anger (negative) faces in the control but not expectancy condition. Interestingly, lateralisation differed for face gender, revealing a left hemisphere advantage for male faces and a right hemisphere advantage for female faces. In the word task, an affective priming effect was found, with higher accuracy when valence of picture prime and word target were congruent. Target words were also responded to faster when presented to the LVF versus RVF in the expectancy but not control condition. These findings suggest that expecting an emotion influences laterality processing but that this differs in terms of the perceptual/experience dimension of the task. Further, that hemispheric processing of emotional expressions appear to differ in the gender of the image.

Approach motivational body postures lean toward left frontal brain activity

The present experiment examined the effect of different approach motivational body postures on relative left frontal cortical activity, which has been linked with approach motivation. Three body postures were manipulated to create three levels of approach motivation. Consistent with the motivational direction model, results indicated that leaning forward with arms extended (high approach) caused greater left frontal cortical activation as compared to reclining backwards (low approach). This is the first experiment to demonstrate this effect, and it suggests that leaning forward as compared to reclining backward increases approach motivation. These results provide important implications for the motivational direction model and embodiment research.

Trait Approach Motivation Relates to Dissonance Reduction

Over 50 years of work on cognitive dissonance theory has suggested that dissonance reduction is a motivated process. However, no research has unambiguously demonstrated the direction of this motivation—whether it is approach or avoidance oriented. The action-based model of dissonance proposes that dissonance reduction is an approach-related process that assists in the implementation of decisions. It follows from the action-based model that approach-related personality traits should be related to greater dissonance reduction. The current research tested this idea. Study 1 found that trait behavioral approach sensitivity (BAS) related to more spreading of alternatives (more liking for the chosen over the rejected decision alternative) following a difficult decision. Study 2 found that BAS related to attitudes being more consistent with recent induced compliance behavior. This research therefore suggests that dissonance reduction is an approach-motivated process.

Socially explosive minds: the triple imbalance hypothesis of reactive aggression

The psychobiological basis of reactive aggression, a condition characterized by uncontrolled outbursts of socially violent behavior, is unclear. Nonetheless, several theoretical models have been proposed that may have complementary views about the psychobiological mechanisms involved. In this review, we attempt to unite these models and theorize further on the basis of recent data from psychological and neuroscientific research to propose a comprehensive neuro-evolutionary framework: The Triple Imbalance Hypothesis (TIH) of reactive aggression. According to this model, reactive aggression is essentially subcortically motivated by an imbalance in the levels of the steroid hormones cortisol and testosterone (Subcortical Imbalance Hypothesis). This imbalance not only sets a primal predisposition for social aggression, but also down-regulates cortical-subcortical communication (Cortical-Subcortical Imbalance Hypothesis), hence diminishing control by cortical regions that regulate socially aggressive inclinations. However, these bottom-up hormonally mediated imbalances can drive both instrumental and reactive social aggression. The TIH suggests that reactive aggression is differentiated from proactive aggression by low brain serotonergic function and that reactive aggression is associated with left-sided frontal brain asymmetry (Cortical Imbalance Hypothesis), especially observed when the individual is socially threatened or provoked. This triple biobehavioral imbalance mirrors an evolutionary relapse into violently aggressive motivational drives that are adaptive among many reptilian and mammalian species, but may have become socially maladaptive in modern humans.

Cultural Variations in Motivational Responses to Felt Misunderstanding

Three studies examined cultural variations in the motivational consequences of being misunderstood by others. Study 1 found that European American students who felt misunderstood by others performed progressively better academically, whereas Asian and Asian American students who felt misunderstood by others performed progressively worse. In Studies 2 and 3, felt misunderstanding was experimentally manipulated, and motivational responses were measured with a handgrip task (Study 2) and prefrontal electroencephalography (EEG) asymmetry (Study 3). Across the two studies, Asians and Asian Americans showed more withdrawal-related responses but European Americans showed either no difference (Study 2) or more motivated responses (Study 3) after being misunderstood versus being understood. Together, these studies demonstrate systematic cultural variations in motivational responses to felt misunderstanding.

Asymmetric frontal cortical activity and negative affective responses to ostracism

Ostracism arouses negative affect. However, little is known about variables that influence the intensity of these negative affective responses. Two studies fill this void by incorporating work on approach- and withdrawal-related emotional states and their associated cortical activations. Study 1 found that following ostracism anger related directly to relative left frontal cortical activation. Study 2 used unilateral hand contractions to manipulate frontal cortical activity prior to an ostracizing event. Right-hand contractions, compared to left-hand contractions, caused greater relative left frontal cortical activation during the hand contractions as well as ostracism. Also, right-hand contractions caused more self-reported anger in response to being ostracized. Within-condition correlations revealed patterns of associations between ostracism-induced frontal asymmetry and emotive responses to ostracism consistent with Study 1. Taken together, these results suggest that asymmetrical frontal cortical activity is related to angry responses to ostracism, with greater relative left frontal cortical activity being associated with increased anger.

Prodromal symptoms and atypical affectivity as predictors of major depression in juveniles: implications for prevention

BACKGROUND

Given the long-term morbidity of juvenile-onset major depressive disorder (MDD), it is timely to consider whether more effort should be dedicated to its primary and secondary prevention.

METHODS

We reviewed studies of prodromal symptoms that may herald a first episode pediatric MDD and considered whether that literature has made an impact on secondary prevention (efforts to prevent progression from symptoms to full disorder). We also reviewed studies of children at familial risk for MDD that addressed atypical affectivity and the regulation of sad, dysphoric affect (mood repair) and related physiological systems, and considered whether research in those areas has made an impact on primary prevention of pediatric MDD (efforts to prevent the disorder).

RESULTS

A compelling body of literature indicates that depressive symptoms in youngsters predict subsequent MDD across the juvenile (and early adult) years and that any combination of several symptoms for at least one week is informative in that regard. These findings are echoed in the case selection criteria used by many secondary prevention programs. Convergent findings also indicate that (compared to typical peers) young offspring at familial risk for depression manifest low positive affectivity and compromised mood repair, along with signs of dysfunction in three intertwined physiological systems that contribute to affectivity and mood repair (the hypothalamic-pituitary-adrenal (HPA) axis, cerebral hemispheric asymmetry, and cardiac vagal control). While all these affect-related parameters are suitable for case selection and as intervention targets, they have not yet made an impact on primary prevention programs.

CONCLUSIONS

According to recent meta-analyses, attempts to prevent pediatric depression have not lived up to expectations. Based on our review, possible reasons for this include: (a) the use of case selection criteria that yield samples heterogeneous with regard to whether the symptoms are truly prodromal to an episode of MDD or are trait-like (which could affect response to the intervention), (b) failure to fully capitalize on the broad-ranging literature on vulnerability to pediatric MDD, as evidenced by the infrequent use of family history of depression (a robust index of vulnerability) or combined indices of vulnerability for case selection, and (c) lack of synchrony between dimensions of vulnerability and the content of the prevention program, as indicated by the overwhelming use of cognitive-behavioral interventions, irrespective of subjects' age, developmental readiness, and whether or not they evidenced the relevant cognitive vulnerability. Prevention trials of pediatric MDD could benefit from new approaches to case selection that combine various indices of vulnerability, more effective use of existing findings, and new or modified interventions that are developmentally sensitive.

Line bisection as a neural marker of approach motivation

Approach motivation has been reliably associated with relative left prefrontal brain activity as measured with electroencephalography (EEG). Motivation researchers have increasingly used the line bisection task, a behavioral measure of relative cerebral asymmetry, as a neural index of approach motivation-related processes. Despite its wide adoption, however, the line bisection task has not been confirmed as a valid measure of the precise pattern of activity linked to approach motivation. In two studies, we demonstrate that line bisection bias is specifically related to baseline, approach-related, prefrontal EEG alpha asymmetry (Study 1) and is heightened by the same situational factors that heighten the same approach-related prefrontal EEG alpha asymmetry (Study 2). Results support the line bisection task as an efficient and unobtrusive behavioral neuroscience measure of approach motivation.

Neuromarketing: the hope and hype of neuroimaging in business

The application of neuroimaging methods to product marketing - neuromarketing - has recently gained considerable popularity. We propose that there are two main reasons for this trend. First, the possibility that neuroimaging will become cheaper and faster than other marketing methods; and second, the hope that neuroimaging will provide marketers with information that is not obtainable through conventional marketing methods. Although neuroimaging is unlikely to be cheaper than other tools in the near future, there is growing evidence that it may provide hidden information about the consumer experience. The most promising application of neuroimaging methods to marketing may come before a product is even released - when it is just an idea being developed.

What happens when we get angry? Hormonal, cardiovascular and asymmetrical brain responses

This study aimed to evaluate neuroendocrine and cardiovascular responses together with changes in brain asymmetry following an anger mood induction laboratory task. Previous research has shown an increase in heart rate and blood pressure when anger is experienced. Increased testosterone and decreased cortisol in response to anger and aggressive behavior have also been reported. With regard to asymmetrical frontal brain activity and emotion, the valence model links negative affect (as anger) to the right hemisphere while the motivational direction model links approach-related emotions (as anger) to the left hemisphere. From the subjective perception and from the neuroendocrine and cardiovascular response of the subjects, we can conclude that the self-referent statement anger induction method by Engebretson et al. (1999) was able to generate an experience of an anger affect in 30 healthy men. Another question was to analyze the consequences of that experience upon perceptual asymmetry when measured with a non-emotional laterality task. Regarding dichotic listening, an enhanced REA (right ear advantage) was observed after anger which indicates greater left hemisphere activity, supporting the motivational direction model.

Frontal brain electrical asymmetry and cardiac vagal tone predict biased attention to social threat

Individual differences in attention biases for motivationally significant stimuli have been reported in clinical and normative populations. Few studies, however, have attempted to examine potential biological mechanisms underlying differences in the cognitive processing of emotional stimuli. The present study examined the extent to which two well-validated psychophysiological vulnerability markers of affective style [i.e., frontal electroencephalogram (EEG) asymmetry and cardiac vagal tone] predicted biased attention toward rapid presentations (approximately 250 ms) of angry and happy facial expressions. We found that right frontal EEG asymmetry and low cardiac vagal tone, taken together, predicted approximately 37% of the variability in attentional vigilance for angry faces. Frontal EEG asymmetry and cardiac vagal tone did not predict attention for happy faces, independently of each other. Our results provide preliminary evidence that two well established psychophysiological indicators of affective style bias early processing of motivationally salient stimuli.

Emotional MMN: Anxiety and heart rate correlate with the ERP signature for auditory change detection

OBJECTIVE

Previous work established the mismatch negativity (MMN) as a correlate of pre-attentive auditory change detection. The present study aimed at investigating the relationship between the MMN and emotional processes associated with the detection of change.

METHODS

To this end, we assessed state anxiety with a questionnaire and subsequently recorded the electroencephalogram (EEG) and heart rate while participants watched a silent movie and listened to a task-irrelevant auditory oddball sequence. The oddball sequence comprised meaningless syllables of which some were deviants spoken with an angry or neutral voice.

RESULTS

The MMN to angry voice deviants was larger than that to neutral deviants and correlated positively with ensuing heart rate acceleration. Additionally, both the MMN and heart rate acceleration to angry voice deviants were increased with increasing state anxiety. A similar effect for neutral voice deviants was non-significant.

CONCLUSION

Taken together, these results suggest that the pre-attentive processing of threat, as reflected by the MMN, is linked to an activation of the sympathetic nervous system. Moreover, this link is more strongly activated in individuals with high state anxiety.

SIGNIFICANCE

Thus, the MMN may be used as a marker for an individual's state dependent sensitivity to unattended, emotionally relevant change.

Regional brain activation and affective response to physical activity among healthy adolescents

Research has shown that frontal brain activation, assessed via electroencephalographic (EEG) asymmetry, predicts the post-exercise affective response to exercise among adults. Building on this evidence, the present study investigates the utility of resting cortical asymmetry for explaining variance in the affective response both during and after exercise at two different intensities among healthy adolescents. Resting EEG was obtained from 98 adolescents (55% male), who also completed two 30-min exercise tasks on a cycle ergometer at a moderate and hard intensity. Affect (as measured by the Feeling Scale) was assessed prior to exercise, every 10min during exercise, immediately post-exercise, and 10min post-exercise. When moderate exercise was performed first, resting frontal cortical asymmetry was related to the affective response to moderate exercise, such that left-dominant adolescents reported more positive affect compared to right-dominant adolescents. When hard exercise was performed first, the association was not significant. The results are interpreted in light of current theory related to affect in response to exercise.

The testosterone-cortisol ratio: A hormonal marker for proneness to social aggression

Social aggression is an escalating hazard for individuals and society. It is most frequently observed as impulsive-reactive aggression in antisocial personality disorder (APD), but in psychopathic aggressive personalities instrumental social aggression is more prominent. However, the psychobiological mechanisms underlying human social aggression are still poorly understood. Here we propose a psychobiological mechanism that may explain human social aggression wherein the steroid hormones cortisol and testosterone play a critical role. High levels of testosterone and low levels of cortisol have been associated with social aggression in several species but it seems that in those individuals wherein these hormonal markers combine social aggression is most violent. In this review we discuss fundamental and clinical research which underscores the potential of the testosterone-cortisol ratio as a possible marker for criminal aggressive tendencies.

Asymmetric prefrontal cortex activation in relation to markers of overeating in obese humans

Dietary restraint is heavily influenced by affect, which has been independently related to asymmetrical activation in the prefrontal cortex (prefrontal asymmetry) in electroencephalograph (EEG) studies. In normal weight individuals, dietary restraint has been related to prefrontal asymmetry; however, this relationship was not mediated by affect. This study was designed to test the hypotheses that, in an overweight and obese sample, dietary restraint as well as binge eating, disinhibition, hunger, and appetitive responsivity would be related to prefrontal asymmetry independent of affect at the time of assessment. Resting EEG recordings and self-report measures of overeating and affect were collected in 28 overweight and obese adults. Linear regression analyses were used to predict prefrontal asymmetry from appetitive measures while controlling for affect. Cognitive restraint and binge eating were not associated with prefrontal asymmetry. However, disinhibition, hunger, and appetitive responsivity predicted left-, greater than right-, sided prefrontal cortex activation independent of affect. Findings in this study add to a growing literature implicating the prefrontal cortex in the cognitive control of dietary intake. Further research to specify the precise role of prefrontal asymmetry in the motivation toward, and cessation of, feeding in obese individuals is encouraged.

Assessment of preschoolers' positive empathy: concurrent and longitudinal relations with positive emotion, social competence, and sympathy

The purpose of this study was to examine a new measure of children's dispositional positive empathy (i.e., reactions to others' positive emotions) and its concurrent and longitudinal relations with positive emotion, social competence, and empathy/sympathy with negative emotions. At Time 1, 192 3.5-year-olds (88 girls) participated; at Time 2, 1 year later, 168 4.5-year-olds (79 girls) participated. Children's positive empathy was reported by mothers and observed in the laboratory at Time 2. Additionally, mothers, fathers, and non-parental caregivers completed questionnaires at Time 1 and Time 2 regarding children's positive emotion, empathy/sympathy, and social competence. Children's positive emotion was observed at both assessments. There was evidence of reliability of the new reported measure of positive empathy. Additionally, there were numerous positive relations between positive empathy and social competence and between positive empathy and empathy/sympathy with negative emotions. This study provides unique insight into children's positive empathy and relations to socio-emotional functioning.

When frustration is repeated: behavioral and emotion responses during extinction over time

Persistence of instrumental responding and negative facial expressions in response to repeated goal blockage was studied in 53 4-month-old infants. All participants experienced 2 sessions comprising baseline (no stimulation), contingency (stimulation resulting from infant action), and extinction (no stimulation) on consecutive days. Performance criteria identified 2 groups of infants, those who learned in Session 1 (Learning Group 1) and those who learned in Session 2 (Learning Group 2). Individual differences in instrumental responses and facial expression during extinction were compared as a function of learning group. Across sessions, the repetition of extinction for Learning Group 1 was associated with both a persistent instrumental response and anger expressions. The level of instrumental response and anger expression was equivalent to that observed for Learning Group 2 but only in Session 2, the day on which that group learned. Sadness and anger/sadness blended expressions were initially more common in Learning Group 2, but these expressions were attenuated given another exposure to the contingency in Session 2. Implications for the relations among infant emotion, cognition, and behavior are discussed.

Neural correlates of individual differences related to appetite

Using neuroimaging technologies to compare normal weight and obese individuals can reveal much about the pathophysiological state of obesity but such comparisons tell us little about what makes some normal weight individuals susceptible to obesity or about important individual differences amongst obese individuals. The current review therefore reviews neuroimaging research on individual difference measures that can illuminate these important topics. After introducing three neuropsychological models of the nature of motivation to approach rewarding stimuli, neuroimaging research on measures of impulsivity, craving, binge eating, restrained eating and disinhibited eating is reviewed. Although neuroimaging research on individual differences measures of brain activity related to appetite is in its infancy, existing studies suggest that such research could enrich the understanding, prevention and treatment of disordered eating and obesity.

Social power and approach-related neural activity

It has been argued that power activates a general tendency to approach whereas powerlessness activates a tendency to inhibit. The assumption is that elevated power involves reward-rich environments, freedom and, as a consequence, triggers an approach-related motivational orientation and attention to rewards. In contrast, reduced power is associated with increased threat, punishment and social constraint and thereby activates inhibition-related motivation. Moreover, approach motivation has been found to be associated with increased relative left-sided frontal brain activity, while withdrawal motivation has been associated with increased right sided activations. We measured EEG activity while subjects engaged in a task priming either high or low social power. Results show that high social power is indeed associated with greater left-frontal brain activity compared to low social power, providing the first neural evidence for the theory that high power is associated with approach-related motivation. We propose a framework accounting for differences in both approach motivation and goal-directed behaviour associated with different levels of power.

Neural activity underlying the effect of approach-motivated positive affect on narrowed attention

Positive affects high in approach motivational intensity narrow attention. The present study extended this recent finding by testing whether a neural activation associated with approach-motivation intensity--relative left frontal-central activity--would underlie the effect of appetitive stimuli on narrowed attention (as measured by local attentional bias). It also tested whether individual differences in approach motivation relate to this attentional narrowing. Results supported predictions, suggesting a common association of relative left frontal hemispheric processing for approach-motivational processes and narrowed attention.

Dynamic variation in pleasure in children predicts nonlinear change in lateral frontal brain electrical activity

Individual variation in the experience and expression of pleasure may relate to differential patterns of lateral frontal activity. Brain electrical measures have been used to study the asymmetric involvement of lateral frontal cortex in positive emotion, but the excellent time resolution of these measures has not been used to capture second-by-second changes in ongoing emotion until now. The relationship between pleasure and second-by-second lateral frontal activity was examined with the use of hierarchical linear modeling in a sample of 128 children ages 6-10 years. Electroencephalographic activity was recorded during "pop-out toy," a standardized task that elicits pleasure. The task consisted of 3 epochs: an anticipation period sandwiched between 2 play periods. The amount of pleasure expressed during the task predicted the pattern of nonlinear change in lateral frontal activity. Children who expressed increasing amounts of pleasure during the task exhibited increasing left lateral frontal activity during the task, whereas children who expressed contentment exhibited increasing right/decreasing left activity. These findings indicate that task-dependent changes in pleasure relate to dynamic, nonlinear changes in lateral frontal activity as the task unfolds.