Affective style, psychopathology, and resilience: Brain mechanisms and plasticity.

The brain circuitry underlying emotion includes several territories of the prefrontal cortex (PFC), the amygdala, hippocampus, anterior cingulate, and related structures. In general, the PFC represents emotion in the absence of immediately present incentives and thus plays a crucial role in the anticipation of the future affective consequences of action, as well as in the persistence of emotion following the offset of an elicitor. The functions of the other structures in this circuit are also considered. Individual differences in this circuitry are reviewed, with an emphasis on asymmetries within the PFC and activation of the amygdala as 2 key components of affective style. These individual differences are related to both behavioral and biological variables associated with affective style and emotion regulation. Plasticity in this circuitry and its implications for transforming emotion and cultivating positive affect and resilience are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A large-scale investigation of lateralization in cortical anatomy and word reading: Are there sex differences?

The authors report findings of a large-scale, multitask investigation of sex differences in both structural asymmetries and lateralization of word reading. Two hundred participants were tested in eight divided visual field lexical tasks, and each received a structural magnetic resonance imaging scan. The authors examined whether there was evidence for sex differences in overall measures of neuroanatomical and behavioral lateralization, in specific language tasks and brain regions, and in variation in asymmetry within and across tasks and brain regions. There was very little evidence for sex differences on any behavioral measure. The few indications of sex differences in the current report accounted for 2% or less of the individual variation in asymmetry and could not be replicated in independent subsamples. No sex differences were observed in the asymmetry of structures in Broca's and Wernicke's areas such as pars triangularis, pars opercularis, the planum temporale, planum parietale, or Heschl's gyrus. There were also no sex differences in the variability of neuroanatomical asymmetries within or between brain regions. However, a significant relationship between planum temporale and behavioral asymmetry was restricted to men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralized response to diazepam predicts temperamental style in rhesus monkeys.

Based on previous findings in humans and rhesus monkeys suggesting that diazepam has asymmetrical effects on frontal lobe activity and other literature supporting a role for the benzodiazepine system in the mediation of individual differences in anxiety and fearfulness, the relation between asymmetrical changes in scalp-recorded regional brain activity in response to diazepam and the temperamental dimension of behavioral inhibition indexed by freezing time in 9 rhesus monkeys was examined. Animals showed greater relative left-sided frontal activation in response to diazepam compared with the preceding baseline. The magnitude of this shift was strongly correlated with an aggregate measure of freezing time (r?=?.82). The implications of these findings for understanding the role of regional differences in the benzodiazepine system in mediating individual differences in fearfulness are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Autonomic feedback in stressful environments: How do individual differences in autonomic feedback relate to burnout, job performance, and job attitudes in salespeople?

Individual differences in autonomic feedback—the dispositional tendency to experience signs and symptoms of autonomic nervous system activity in response to positive and negative emotionally evocative stimuli—were hypothesized to relate to affective and behavioral job outcomes in occupations characterized by job stress because higher autonomic feedback would intensify reactions to emotional evocation. In a cross-sectional study of Dutch salespeople, individual differences in autonomic feedback were independent of role stress and yet were strongly and positively related to burnout and negatively related to extra-role performance and job satisfaction; they were also nonsignificantly and negatively related to in-role job performance. Further, when job stress was higher–high role stress or low managerial support–individual differences in autonomic feedback were more strongly related to burnout, especially emotional exhaustion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of emotion in a dichotic listening task: event-related brain potential and behavioral findings

The lateralization of emotion perception has been examined using stimuli in both auditory and visual modalities. Studies using dichotic stimuli have generally supported the hypothesis of right-hemisphere dominance for emotion perception, whereas studies of facial and verbal emotion perception have provided evidence for the right-hemisphere and valence hypotheses. A dichotic target detection task was developed to enable acquisition of event-related potentials (ERP) from subjects engaged in emotion detection. Nonsense syllables (e.g., ba, pa) stated in seven different emotional intonations were dichotically presented to 24 young adults, in a target detection task during four separate blocks (target emotions: happiness, interest, anger, or sadness). Accuracy and reaction time and ERP measures were also collected. ERPs were recorded from 14 scalp electrodes with a nose reference and quantified for N100, sustained negativity, late positivity, and slow wave. Significantly greater left- than right-ear accuracy was obtained for the identification of target prosodic emotion. Hemispheric asymmetries of N100 and sustained negativity were found, with left-hemisphere amplitudes greater than right-hemisphere amplitudes. These ERP asymmetries were not significantly correlated with the left-ear dichotic advantage and may be related more to early phonetic processing than to emotion perception. Since the behavioral evidence supports the right-hemisphere hypothesis for emotion perception, behavioral and ERP asymmetries evident in this task reflect separable patterns of brain lateralization.     

Frontal electroencephalographic correlates of individual differences in emotion expression in infants: a brain systems perspective on emotion

Emotion expressions can be characterized by both the type of emotion displayed and the intensity with which the emotion is expressed. Individual differences in these two aspects of emotion appear to vary independently and may perhaps account for distinct dimensions of temperament, personality, and vulnerability to psychopathology. We reviewed several sets of data gathered in our laboratory that indicate that these two dimensions of emotion expression are associated with distinct and independent patterns of frontal EEG activity in infants. Specifically, whereas the type of emotion expression was found to be associated with asymmetries in frontal EEG activity, the intensity of emotion expression was found to be associated with generalized activation of both the right and the left frontal regions. Moreover, we reviewed and provided evidence that measures of asymmetrical frontal activity are better predictors of individual differences in the tendency to express certain emotions, such as distress and sadness, whereas measures of generalized frontal activity are better predictors of individual differences in emotional reactivity and emotion intensity. The neuroanatomical bases of emotion were discussed with special reference to the role of the frontal lobe in emotion regulation. It was hypothesized that the frontal activation asymmetries that have been found to accompany emotion expressions reflect specific regulation strategies. The left frontal region is specialized for regulation strategies involving action schemes that serve to maintain continuity and stability of the organism-environment relation and of ongoing motor schemes, such as those involved in language and the expression of happiness and interest. In contrast, the right frontal region appears to be specialized for regulation strategies that involve processing novel stimuli that disrupt ongoing activity, such as might occur during the expression of fear, disgust, and distress. Furthermore, it was proposed that individual differences in patterns of frontal EEG asymmetries during emotion may be related to socialization influences rather than solely innate factors. It was speculated that the pattern of generalized frontal lobe activation that accompanies the experience of intense emotions may reflect, in part, the relatively diffuse influence of subcortical structures on the cortex and may serve to increase the infant's general readiness to receive and respond to significant external stimuli.     

Postresuscitation changes in brain free radical-mediated processes and nitric oxide synthase activity in rats: effects of individual behavior in "emotional resonance" test

Effects of 7-min cardiac arrest and individual behavior on free radical-mediated processes and nitric oxide synthase (NOS) activity was evaluated in brains of male Wistar rats one hour and one week after resuscitation. "Emotional resonance" test was used for the behavioral selection of rats. The test includes factors of significance for rats: the choice between large and lighted or small and dark space as well as signals of pain of another rat. Free radical generation (using chemiluminescence method), superoxide scavenging/generating activity, substances reacting with 2-thiobarbituric acid and NOS activity (by measuring mononitrosyl iron complex of NO with diethyl dithiocarbamate and endogenous brain Fe2+ by electron spin resonance spectroscopy) were determined in cerebral cortex, cerebellum and hippocampus. Cardiac arrest induced oxidative stress accompanied by the loss of NOS activity, as well as compensatory changes of free radical-mediated processes in cerebral cortex. Oxidative stress was also evident in cerebellum and, to a lesser extent, in hippocampus. Most of neurochemical differences between behavioral groups were induced by cardiac arrest. These differences were global, related to a specific brain region or became apparent in cerebral lateralization of biochemical indices.     

Parsing affective space: Perspectives from neuropsychology and psychophysiology.

Reviews selective behavioral, psychophysiological, and neuropsychological research bearing on how affective space should be parsed. Neither facial expression nor autonomic nervous system activity is found to provide unique markers for particular discrete emotions. The dimensions of approach and withdrawal are introduced as fundamental systems relevant to differentiating affective space. The role of frontal and anterior temporal asymmetries in mediating approach- and withdrawal-related emotion is considered. Individual differences in tonic anterior activation asymmetry are present and are relatively stable over time. Such differences are associated with an individual's propensity to display different types of emotion, mood, and psychopathology. The conceptual and methodological implications of this perspective are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental regulation of the brain polyamine-stress-response

A transient increase in brain polyamine metabolism, termed the polyamine-stress-response is a common response to stressful stimuli. Previous studies have implicated an over-reactive polyamine response as a component of the maladaptive brain response to stressful events, and as a novel molecular mechanism involved in the pathophysiology of affective disorders. Ample evidence indicates that stressful experiences during early life can alter normal developmental processes and may result in pathophysiological and behavioral changes in the adult. Additionally, an important characteristic of affective disorders is their age dependency, a phenomenon that may be correlated with a maladaptive regulation of the hypothalamic-pituitary-adrenocortical (HPA) neuroendocrine system. In the present study we measured the activities of the enzymes ornithine decarboxylase and S-adenosylmethionine decarboxylase as markers of polyamine synthesis and found that unlike adults, immature rats do not show the characteristic brain polyamine-stress-response. Instead of the characteristic increase observed in adults, ornithine decarboxylase activity in immature animals was reduced or remained unchanged (for up to 16 days of age) after a dexamethasone injection or restraint stress application. The ontogenesis of this ornithine decarboxylase response was brain region-specific, indicating its dependence on the stage of neuronal maturation. Animals treated with dexamethasone at 7 days of age, showed increased behavioral reactivity in the open-field test as adults and an attenuated increase in ornithine decarboxylase activity after a re-challenge with dexamethasone at age 60 days. The results indicate that: (1) the brain polyamine-stress-response is developmentally regulated and its ontogenesis is brain region-specific, indicating dependence on the stage of neuronal maturation; (2) the switch to a mature polyamine-stress-response pattern coincides with the cessation of the stress hyporesponsive period in the HPA system: (3) activation of the polyamine-stress-response, as in the mature brain, appears to be a constructive reaction, while its down-regulation, as in the developing brain, may be implicated in neuronal cell death; (4) an attenuated dexamethasone-induced increase in ornithine decarboxylase activity implicates an altered polyamine-stress-response in the maladaptive response of the brain to stressful events.     

Cognitive operations associated with individual differences in affect intensity.

There are individual differences in the characteristic intensity of affective response to the same emotion-evoking event. The processes whereby individuals come to experience strong or mild emotional responses when exposed to the same affect-provoking stimuli are still unclear. In these studies, we propose that individual differences in affect intensity are associated with certain cognitive operations that involve personalizing, generalizing, and selective abstraction were hypothesized to discriminate subjects high and low in affect intensity. Two studies replicated support for the hypothesis that subjects high on affect-intensity dimension engage in more personalizing/empathic and more generalizing/elaborative cognitive operations than do subjects low on the affect-intensity dimension. The same cognitive operations discriminated groups high and low in affect intensity in response to both positive and negative emotional stimuli. Also, the cognitions that discriminated subjects high and low in affect intensity occurred only in response to affective stimuli; neutral stimuli did not evoke divergent cognitive operations for these groups. Finally, a high degree of consistency was found in the use of emotion-relevant cognitive operations across positive and negative stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral activation sensitivity and resting frontal EEG asymmetry: Covariation of putative indicators related to risk for mood disorders.

Dispositional tendencies toward appetitive motivation have been hypothesized to be related to the development of psychopathology. Moreover, decreased left-frontal cortical activity has been reported in depression and has been related to low-trait positive affect and high-trait negative affect. The present study tested the hypothesis that relatively greater left- than right-frontal cortical activity would be related to heightened approach related dispositional tendencies. Resting frontal cortical asymmetrical activity, as measured by electroencephalographic activity in the alpha band, was examined in relation to the motivational response tendencies of a behavioral activation system (BAS) and a behavioral inhibition system (BIS), as measured by C. S. Carver and T. L. White's (see record 1995-00067-001) BIS-BAS self-report questionnaire. Results supported the hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuroticism and brain responses to anticipatory fear.

Personality is known to influence cognitive and affective functioning as well as the risk of psychiatric disorders. Exploration of the neurobiological correlates of personality traits has the potential to enhance understanding of their significance in development of related psychopathological states. The authors examined the association between individual differences in neuroticism and brain activity in response to threat of electric shocks. Fourteen right-handed healthy men underwent functional MRI during a 5-min experiment that involved repeated presentations of two 30-s alternating conditions. In 1 of these conditions, subjects were told to expect mild but painful electric shocks; there was no possibility of receiving shocks in the other condition. The results revealed that neuroticism correlated positively with the ratings of fear of shock and negatively (indicating suppression) with brain activity from safe to shock conditions in the anterior and posterior cingulate, superior/middle temporal gyrus extending to the hippocampus, precuneus, putamen, thalamus, and middle occipital gyrus. The observations support recent psychophysiological research that has demonstrated reduced processing of pain in subjects with higher levels of neuroticism, especially the anxiety component of this trait. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetrical distribution of hippocampal mineralocorticoid receptors depends on lateralization in mice

Previous experiments showed that the activation of the hypothalamic-pituitary-adrenal (HPA) axis during stress was associated with behavioral lateralization used as a marker of population heterogeneity in mice. Furthermore, brain asymmetries have been demonstrated in neurotransmitter metabolism and neuroendocrine modulation. As the hippocampus modulates the activity of the HPA axis in stress and basal conditions, we postulated that hippocampal corticoid receptors may be asymmetrically distributed and that asymmetry may differ according to behavioral lateralization of animals. In order to answer these questions, binding capacity of mineralocorticoid (MR) and glucocorticoid (GR) receptors was determined in right and left hippocampi of mice previously selected for paw preference. The results show that regardless of behavioral lateralization, there was a tendency for a right dominance in MR binding capacity in the hippocampus but interestingly, the percentage of right/ total MR binding capacity was inversely correlated with individual paw preference scores. The affinity of MRs did not depend on behavioral lateralization. GR binding capacity was similar in each hemisphere and no relationship was found between GR binding capacity and paw preference scores. These results suggest that hippocampal receptors for corticoids may play an important role in the asymmetrical brain control of immune reactivity.     

Frontal brain asymmetry predicts infants' response to maternal separation.

Examined whether certain features of infant temperament might be related to individual differences in the asymmetry of resting frontal activation. EEG was recorded from the left and right frontal and parietal scalp regions of 13 normal 10-month-old infants. Infant behavior was then observed during a brief period of maternal separation. Those infants who cried in response to maternal separation showed greater right frontal activation during the preceding baseline period compared with infants who did not cry. Frontal activation asymmetry may be a state-independent marker for individual differences in threshold of reactivity to stressful events and vulnerability to particular emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiotherapy in the SIOP (International Society of Pediatric Oncology) nephroblastoma studies: a review

It has been proposed that certain adverse early experiences may play a role in determining subsequent susceptibility to adult anxiety and affective disorders and this relationship may be the result of altered neurodevelopment of the noradrenergic and/or serotonergic systems. In this study of nonhuman primates, the predictability of foraging requirements for mothers during an early period of their infants' lives was manipulated. When the offspring were young adults, these early manipulations were related to differences in behavioral response to acute administration of two putative anxiety-provoking agents: the noradrenergic probe, yohimbine, and the serotonergic probe, mCPP. These long-term effects of the developmental environment on subsequent pharmacological responsivity suggest that both neuronal systems may be permanently altered by early experiential factors.     

Individual differences and their relation to social structure in domestic cats.

Two groups of domesticated cats with established social structures were tested for their response to novel stimuli in a variety of test situations. Clear individual differences in responses were consistent over a series of test sessions and remained stable despite regular environmental changes. Individual differences in behavioral response were not related to object dominance (food competition) or social dominance (freedom of movement in social encounters) unlike similar studies with social animals. No relationship was found in either group between a cat's rank in object dominance and its rank in social dominance. Significant correlations were demonstrated in the individual cat's latency to approach a novel stimulus, behavioral rank in test situations, and attention span in both groups of cats. Comparisons were made between similar studies with wolves, and inferences were drawn about the relationship between individual differences and social structure in social and nonsocial species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Situation selection as a moderator of response consistency and stability.

Addressed the viability of introducing into the moderator variable literature a distinction between chosen and imposed situations in 2 studies with 62 undergraduates. In Study 1, the relation between recreational activity choices and selected personality traits and the stability of these choices over time was examined. In Study 2, the cross-situational consistency of affective and behavioral responses within self-rated chosen and imposed situations in Ss' everyday lives was examined. Situational choices were found to be relatively stable over a period of 9 mo and to be related in predictable ways to personality dispositions. Distinguishing between chosen and imposed situations produced differences in average cross-situational consistency coefficients, and differences between affective and behavioral responses were also found. Behavior was found to be more consistent within imposed situations. It is concluded that there is support for the claim that self-selection of individuals to situations moderates response consistency and stability. (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classifying multidimensional stimuli: Stimulus, task, and observer factors.

When observers decide how to classify stimuli, they often employ 1 of 2 types of information: identity along one particular dimension or overall similarity. The present 6 experiments, with 439 undergraduates, examined interrelations among the factors which determine the use of these types of information. Ss' classifications of certain types of materials (e.g., size and brightness, length and density) revealed strong individual differences, were related to the S's response tempo and selective processing ability, and were influenced by task demands. Classifications of other materials (e.g., saturation and brightness) did not reveal individual differences, were not affected by response tempo and selective processing ability, and were unaffected by changes in task demands. The former, but not the latter, types of materials have also been found to be influenced by developmental differences. Findings are consistent with the idea that differences in response tempo and selective processing ability underlie observer differences (both individual and developmental) and that certain types of stimuli that are not susceptible to such influences set boundary conditions for observer differences. The results are discussed within an integral-to-separable model of processing. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in skilled reaching for food related to increased number of gestures: Evidence for goal and habit learning of skilled reaching.

Skilled reaching in rodents and primate is motorically similar, but success in reaching by rodents is distinctively variable. The source of this variability has not been examined previously. Long–Evans rats were videotaped as they reached for food in 2 different reaching tasks, and endpoint measures of performance were examined in relation to variables previously associated with individual differences, including testing procedures, rehabilitation, movement ability, general locomotor activity, and cortical anatomy. There were individual differences in performance, but these were not related to the dependent measures related to training, movement ability, locomotor activity, or anatomy (e.g., brain with cortical thickness, acetylcholinesterase and neuron density, pyramidal tract size). Success was negatively related to numbers of gestures (non–weight-bearing movements of the reaching limb) used on a reach, however. The results are discussed in relation to the idea that individual differences in response strategy bias some rats to use a more successful goal strategy and others to use a less successful habit strategy for skilled reaching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)