Wendy Heller

Patterns of regional brain activity differentiate types of anxiety.

Previous studies have reported hemispheric asymmetries in brain activity in anxiety, but the direction of asymmetry has been inconsistent. A distinction between anxious apprehension (e.g., worry) and anxious arousal (e.g., panic), as types of anxiety, may account for some of the discrepancies. To test this proposition, the authors selected participants with self-reported anxious apprehension and experimentally manipulated anxious arousal. Regional brain activity was examined by recording electroencephalograms during rest and during an emotional narrative task designed to elicit anxious arousal. Overall, anxious participants showed a larger asymmetry in favor of the left hemisphere than did controls. In contrast, during the task, anxious participants showed a selective increase in right parietal activity. The results support the hypothesis that anxious apprehension and anxious arousal are associated with different patterns of regional brain activity.

Paying attention to emotion: An fMRI investigation of cognitive and emotional Stroop tasks

In this research, we investigated the degree to which brain systems involved in ignoring emotionally salient information differ from those involved in ignoring nonemotional information. The design allowed examination of regional brain activity, using fMRI during color-word and emotional Stroop tasks. Twelve participants indicated the color of words while ignoring word meaning in conditions in which neutral words were contrasted to emotionally negative, emotionally positive, and incongruent color words. Dorsolateral frontal lobe activity was increased by both negative and incongruent color words, indicating a common system for maintaining an attentional set in the presence of salient distractors. In posterior regions of the brain, activity depended on the nature of the information to be ignored. Ignoring color-incongruent words increased left parietal activity and decreased parahippocampal gyrus activity, whereas ignoring negative emotional words increased bilateral occipito-temporal activity and decreased amygdala activity. The results indicate that emotion and attention are intimately related via a network of regions that monitor for salient information, maintain attention on the task, suppress irrelevant information, and select appropriate responses.

The Puzzle of Regional Brain Activity in Depression and Anxiety: The Importance of Subtypes and Comorbidity

The literature on brain activity in depression and anxiety is reviewed with an on highlighting discrepancies and inconsistencies. In particular, and posterior asymmetries have been reported for both depression anxiety, but the magnitude and direction of these asymmetries has been We propose that by identifying subtypes of depression and anxiety of these inconsistencies can be explained. In addition, we review suggesting that issues of comorbidity are important to consider in to account for regional brain activity in depression and anxiety.

Are variations among right-handed individuals in perceptual asymmetries caused by characteristic arousal differences between hemispheres?

We propose that much of the variance among right-handed subjects in perceptual asymmetries on standard behavioral measures of laterality arises from individual differences in characteristic patterns of asymmetric hemispheric arousal. Dextrals with large right-visual-field (RVF) advantages on a tachistoscopic syllable-identification task (assumed to reflect characteristically higher left-hemisphere than right-hemisphere arousal) outperformed those having weak or no visual-field asymmetries (assumed to reflect characteristically higher right-hemisphere than left-hemisphere arousal). The two groups were equal, however, in asymmetries of error patterns that are thought to indicate linguistic or nonlinguistic encoding strategies. For both groups, relations between visual fields in the ability to discriminate the accuracy of performance followed the pattern of syllable identification itself, suggesting that linguistic and metalinguistic processes are based on the same laterally specialized functions. Subjects with strong RVF advantages had a pessimistic bias for rating performance, and those with weak or no asymmetries had an optimistic bias, particularly for the left visual field (LVF). This is concordant with evidence that the arousal level of the right hemisphere is closely related to affective mood. Finally, consistent with the arousal model, leftward asymmetries on a free-vision face-processing task became larger as RVF advantages on the syllable task diminished and as optimistic biases for the LVF, relative to the RVF, increased.

Cognitive control mechanisms, emotion and memory: A neural perspective with implications for psychopathology

In this paper we provide a focused review of the literature examining neural mechanisms involved in cognitive control over memory processes that can influence, and in turn are influenced by, emotional processes. The review is divided into two parts, the first focusing on working memory and the second on long-term memory. With regard to working memory, we discuss the neural bases of (1) control mechanisms that can select against distracting emotional information, (2) mechanisms that can regulate emotional reactions or responses, (3) how mood state influences cognitive control, and (4) individual differences in control mechanisms. For long-term memory, we briefly review (1) the neural substrates of emotional memory, (2) the cognitive and neural mechanisms that are involved in controlling emotional memories and (3) how these systems are altered in post-traumatic stress disorder. Finally, we consider tentative generalizations that can be drawn from this relatively unexplored conjunction of research endeavors.

Contrasting patterns of brain activity in anxious apprehension and anxious arousal

Evidence suggests that a distinction between anxious apprehension (worry) and anxious arousal (somatic anxiety) might account for some discrepancies in the literature examining brain activity in anxiety. In the current study, we compared the regional brain activity of groups of anxious apprehension and anxious arousal participants, selected on the basis of self-report measures previously shown to be psychometrically distinct from each other and from a specific measure of depression. Patterns of hemispheric asymmetry in electroencephalogram alpha distinguished the two types of anxiety, with the anxious arousal group showing more right than left activity. No significant asymmetry was found for the anxious apprehension group. The results provide further support for contrasting patterns of brain activity in distinct types of anxiety. Research is needed to specify further the topography and functional significance of this distinction.

Patterns of Perceptual Asymmetry in Depression and Anxiety: Implications for Neuropsychological Models of Emotion and Psychopathology

More than 1,000 university undergraduates were simultaneously classified as either high or low depressed and high or low anxious and given a face-processing task that typically elicits a left hemispatial bias. Depression and anxiety were associated with opposing biases in perceptual asymmetry scores. In particular, high-depressed students had smaller left hemispatial biases than low-depressed students, whereas high-anxious students had larger left hemispatial biases than low-anxious students. The results suggest that depression and anxiety may be associated with different patterns of asymmetric hemispheric function. Because the rate of comorbidity of depression and anxiety in the population is high, these findings confirm the importance of separating anxiety and depression when examining the relationship among patterns of brain activity, emotion, and psychopathology.

Distinguishing Dimensions of Anxiety and Depression

Symptom covariation and lack of symptom specificity have proven to be complicating factors in research on the emotional, cognitive, and physiologic characteristics of anxiety and depression. Numerous attempts have been made to investigate the unique and overlapping features of anxiety and depression. Of interest in the present study were potential distinctions among proposed types of anxiety and depression. A variety of self-report measures were administered to 783 college students. Correlational analyses and confirmatory factor analyses converged in suggesting that anxious arousal (somatic anxiety) and anxious apprehension (worry) represent distinct affective dimensions that can be distinguished from depression and negative affect.

The time course of activity in dorsolateral prefrontal cortex and anterior cingulate cortex during top-down attentional control

A network of brain regions has been implicated in top-down attentional control, including left dorsolateral prefrontal cortex (LDLPFC) and dorsal anterior cingulate cortex (dACC). The present experiment evaluated predictions of the cascade-of-control model (Banich, 2009), which predicts that during attentionally-demanding tasks, LDLPFC imposes a top-down attentional set which precedes late-stage selection performed by dACC. Furthermore, the cascade-of-control model argues that dACC must increase its activity to compensate when top-down control by LDLPFC is poor. The present study tested these hypotheses using fMRI and dense-array ERP data collected from the same 80 participants in separate sessions. fMRI results guided ERP source modeling to characterize the time course of activity in LDLPFC and dACC. As predicted, dACC activity subsequent to LDLPFC activity distinguished congruent and incongruent conditions on the Stroop task. Furthermore, when LDLPFC activity was low, the level of dACC activity was related to performance outcome. These results demonstrate that dACC responds to attentional demand in a flexible manner that is dependent on the level of LDLPFC activity earlier in a trial. Overall, results were consistent with the temporal course of regional brain function proposed by the cascade-of-control model.

Cognitive deficits in depression and functional specificity of regional brain activity

The growing literature on cognitive deficits in depression is considered in light of regional brain activity as well as comorbid anxiety and life stressors. Cognitive impairments associated with depression are reviewed, with an emphasis on various aspects of executive function such as memory, attention, and problem-solving. These deficits are related to patterns of brain activity observed in prefrontal, anterior cingulate, and parietal cortices, as well as in subcortical regions. Evidence for the largely unexplored role of environmental stressors in depression and their impact on cognition and brain function is also examined, and promising avenues of additional research are noted. In addition to promoting interdisciplinary research, systematically assessing variables such as cognitive performance, comorbid anxiety, and relevant stressors may elucidate distinct patterns of brain function and cognition that could inform prevention and intervention.