Progress in the study of emotion and emotion regulation has increasingly been informed by neuroscientific methods. This article focuses on two components of the event-related potential (ERP)--the P300 and the late positive potential (LPP)--and how they can be used to understand the interaction between the more automatic and controlled processing of emotional stimuli. Research is reviewed exploring: the dynamics of emotional response as indexed at early and late latencies; neurobiological correlates of emotional response; individual and developmental differences; ways in which the LPP can be utilized as a measure of emotion regulation. Future directions for the application of ERP/electroencephalogram (EEG) in achieving a more complete understanding of emotional processing and its regulation are presented.
Emotional pictures elicit enhanced parietal positivities beginning around 300 ms following stimulus presentation. The magnitude of these responses, however, depends on both intrinsic (stimulus-driven) and extrinsic (context-driven) factors. In the present study, event-related potentials were recorded while participants viewed unpleasant and neutral pictures that were described either more neutrally or more negatively prior to presentation; temporospatial principal components analysis identified early and late positivities: Both emotional images and descriptions had independent and additive effects on early (334 ms) and midlatency (1,066 ms) positivities, whereas the latest positivity (1,688 ms) was sensitive only to description type. Results are discussed with regard to the time course of automatic and controlled processing of emotional stimuli.
Threatening stimuli have been shown to preferentially capture attention using a range of tasks and measures. However, attentional bias to threat has not typically been found in unselected individuals using behavioral measures in the dot-probe task, one of the most common ways of examining attention to threat. The present study leveraged event-related potentials (ERPs) in conjunction with behavioral measures in the dot-probe task to examine whether more direct measures of attention might reveal an attentional bias to threat in unselected individuals. As in previous dot-probe studies, we found no evidence of an attentional bias to threat using reaction time; additionally, this measure exhibited poor internal reliability. In contrast, ERPs revealed an initial shift of attention to threat-related stimuli, reflected by the N2pc, which showed moderate internal reliability. However, there was no evidence of sustained engagement with the threat-related stimuli, as measured by the late positive potential (LPP). Together, these results demonstrate that unselected individuals do initially allocate attention to threat in the dot-probe task, and further, that this bias is better characterized by neural measures of attention than traditional behavioral measures. These results have implications for the study of attention to threat in both unselected and anxious populations.
Emotion regulation decreases the processing of arousing stimuli, as indexed by the late positive potential (LPP), an electrocortical component that varies in amplitude with emotional arousal. Emotion regulation increases activity in the prefrontal areas associated with cognitive control, including the dosolateral prefrontal cortex (DLPFC). The present study manipulated working memory load, known to activate the DLPFC, and recorded the LPP elicited by aversive and neutral IAPS pictures presented during the retention interval. The LPP was larger on low-load compared to high-load trials, and on trials with aversive compared to neutral pictures. These LPP data suggest that emotional content and working memory load have opposing effects on attention to distracting stimuli. State anxiety was associated with reduced modulation of the LPP by working memory load. Results are discussed in terms of competition for attention between emotion and cognition and suggest a relationship between DLPFC activation and the allocation of attentional resources to distracting visual stimuli-a relationship that may be disrupted with increasing anxiety.
To examine whether reappraisal modifies responses to subsequent encounters with stimuli, participants viewed neutral and unpleasant pictures that were preceded by negative or neutral descriptions which served as reappraisal frames. A half an hour later, the same pictures were presented, without preceding frames; EEG was recorded and participants rated each picture on arousal and valence. In line with previous work, unpleasant compared to neutral pictures elicited more positive early- (359 ms), mid- (1074 ms) and late-latency (2436 ms) centrally-distributed ERP components. Pictures previously preceded by negative compared to neutral reappraisal frames were rated as more unpleasant and more emotionally arousing; these pictures elicited a larger mid-latency (1074 ms) occipital positivity. Together, the data suggest that reappraisal exerts an enduring effect on both subjective and neural responses to stimuli.
Background
Collectively, functional neuroimaging studies implicate frontal-limbic dysfunction in the pathophysiology of posttraumatic stress disorder (PTSD), as reflected by altered amygdala reactivity and deficient prefrontal responses. These neural patterns are often elicited by social signals of threat (fearful/angry faces) and traumatic reminders (combat sounds, script-driven imagery). Although PTSD can be conceptualized as a disorder of emotion dysregulation, few studies to-date have directly investigated the neural correlates of volitional attempts at regulating negative affect in PTSD.
Methods
Using functional magnetic resonance imaging and a well-validated task involving cognitive regulation of negative affect via reappraisal and known to engage prefrontal cortical regions, the authors compared brain activation in veterans with PTSD (n=21) and without PTSD (n=21, combat-exposed controls/CEC), following military combat trauma experience during deployments in Afghanistan or Iraq. The primary outcome measure was brain activation during cognitive reappraisal (i.e., decrease negative affect) as compared to passive viewing (i.e., maintain negative affect) of emotionally-evocative aversive images.
Results
The subjects in both groups reported similar successful reduction in negative affect following reappraisal. The PTSD group engaged the dorsolateral prefrontal cortex during cognitive reappraisal, albeit to a lesser extent than the CEC group. Although the amygdala was engaged in both groups during passive viewing of aversive images, neither group exhibited attenuation of amygdala activation during cognitive reappraisal.
Conclusions
Veterans with combat-related PTSD showed less recruitment of the dorsolateral prefrontal cortex involved in cognitive reappraisal, suggesting focal and aberrant neural activation during volitional, self-regulation of negative affective states.
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