Amygdala responses to emotionally valenced stimuli in older and younger adults

Abstract— As they age, adults experience less negative emotion, come to pay less attention to negative than to positive emotional stimuli, and become less likely to remember negative than positive emotional materials. This profile of findings suggests that, with age, the amygdala may show decreased reactivity to negative information while maintaining or increasing its reactivity to positive information. We used event-related functional magnetic resonance imaging to assess whether amygdala activation in response to positive and negative emotional pictures changes with age. Both older and younger adults showed greater activation in the amygdala for emotional than for neutral pictures; however, for older adults, seeing positive pictures led to greater amygdala activation than seeing negative pictures, whereas this was not the case for younger adults.     

Neuroimaging of emotion and personality: scientific evidence and ethical considerations

Affective neuroscience has seen an explosion of research efforts using modern neuroimaging approaches to uncover the neural basis of emotion and personality. The first section of this paper reviews studies from the domains of affective and forensic neuroimaging. These studies illustrate some of the topics likely to be the subject of future ethical debates. The second section relates limitations of the neuroimaging approach to ethical considerations in predicting future psychopathology on the basis of brain state analysis.     

Variance maps as a novel tool for localizing regions of interest in imaging studies of individual differences

Cognitive neuroimaging studies of individual differences seek to reveal brain mechanisms of cognition by associating intersubject variability in brain activation with other variables of interest, such as sex, personality trait, or mood state. The choice of a priori regions of interest (ROIs) raises problems, because the selection criterion is typically consistent activation across prior studies, suggesting little intersubject variability. Here, we introduce a novel approach for selecting regions that are defined on the basis of their variance characteristics, rather than on the basis of their location or because of theoretical expectations. These regions of variance (ROVs) constitute the search space with which to assess how much of the observed variance can be ascribed to specific variables of interest. We compare the ROI and ROV approaches by applying each to the same data set and suggest that the conjunction of both methods may yield the greatest likelihood of capturing the rich relation between brain and behavior, while limiting the search space for statistical analyses and minimizing false positive errors.     

Emotion regulation and amygdala-precuneus connectivity: Focusing on attentional deployment

Attentional deployment is an emotion regulation strategy that involves shifting attentional focus. Deploying attention to non-arousing, compared to arousing, regions of unpleasant images has been associated with reduced negative affect, reduced amygdala activation, and increased activity in fronto-parietal control networks. The current study examined neural correlates and functional connectivity associated with using attentional deployment to increase negative affect (deploying attention towards arousing unpleasant information) or to decrease negative affect (deploying attention away from arousing unpleasant information), compared to naturally viewing unpleasant images, in 42 individuals while concurrently monitoring eye movements. Directing attention to both arousing and non-arousing regions resulted in enhanced fronto-parietal activation compared to natural viewing, but only directing attention to non-arousing regions was associated with changes in amygdala activation. There were no significant differences in connectivity between naturally viewing unpleasant images and focusing on arousing regions. However, naturally viewing unpleasant images, relative to focusing on non-arousing regions, was associated with increased connectivity between the amygdala and visual cortex, while focusing on non-arousing regions of unpleasant images, compared to natural viewing, was associated with increased connectivity between the amygdala and the precuneus. Amygdala-precuneus connectivity correlated positively with eye-tracking measures of attentional deployment success and with trait reappraisal. Deploying attention away from arousing unpleasant information, then, may depend upon functional relationships between the amygdala and parietal regions implicated in attentional control. Furthermore, these relationships might relate to the ability to successfully implement attentional deployment, and the predisposition to utilize adaptive emotion regulation strategies.     

Catechol-O-methyltransferase Val158Met genotype affects neural correlates of aversive stimuli processing

It was previously shown that variation of the catechol-O-methyltransferase (COMT) gene modulates brain activity during the processing of stimuli with negative valence, but not for pleasant stimuli. Here, we tested whether the COMT genotype also modulates the electrophysiological correlates of emotional processing and explored whether the environmental factor of life stress influences this effect. Using the early posterior negativity (EPN) paradigm, event-related brain potentials were measured in 81 healthy individuals during the processing of pictures that evoked emotions of positive and negative valence. As was hypothesized, the COMT genotype affected the EPN amplitudes for unpleasant stimuli, but not for pleasant ones. Specifically, Met/Met carriers respond more sensitively to unpleasant stimuli, as compared with Val/Val carriers. We did not find evidence that life stress moderates the effect of the COMT genotype on emotional stimuli processing.     

Interference produced by emotional conflict associated with anterior cingulate activation

The anterior cingulate cortex (ACC) is involved in cognition and emotion. In the classic Stroop task, presentation of stimuli that are in response conflict with one another produces activation in the caudal ACC. In the emotional Stroop task, presentation of emotionally salient stimuli produces activation in the rostral ACC. Presentation of stimuli that are emotionally conflicting should activate the caudal ACC; stimuli that are emotionally salient should activate the rostral ACC. We tested this prediction using functional magnetic resonance imaging while subjects made emotional valence judgments of words overlaid on emotional faces (word-face Stroop task). Emotionally incongruent pairs were responded to more slowly than emotionally congruent pairs. Emotionally incongruent trials were associated with increased activation within the caudal ACC, whereas no ACC activation was found in response to emotional saliency. These results support the conflict-monitoring model of caudal ACC and extend this function to conflict within the domain of emotional stimuli.     

A Neurogenetic Approach to Impulsivity

ABSTRACT Impulsivity is a complex and multidimensional trait that is of interest to both personality psychologists and to clinicians. For investigators seeking the biological basis of personality traits, the use of neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) revolutionized personality psychology in less than a decade. Now, another revolution is under way, and it originates from molecular biology. Specifically, new findings in molecular genetics, the detailed mapping and the study of the function of genes, have shown that individual differences in personality traits can be related to individual differences within specific genes. In this article, we will review the current state of the field with respect to the neural and genetic basis of trait impulsivity.