Patricia J. Deldin

P300 as an index of attention to self-relevant stimuli

Past work suggests that information related to the self receives ‘preferential access’ to the limited pool of attentional resources. However, these studies have been limited by their reliance on response–time measures, which require overt responding and represent the combined effects of multiple stages of information processing. One aim of the present study was to extend past work by obtaining a response-independent index of attention allocation sensitive to changes in discrete stages of information processing. An additional goal was to explore the potential time course of differential sensitivity to self-relevant cues. We assessed the P300, an ERP component that provides an index of attentional resources, evoked by autobiographical self-relevant stimuli (e.g., one’s own name). As expected, P300 was augmented for self-relevant stimuli relative to control stimuli. In addition, analyses of P300 latency indicate that the effects of self-relevance are present during higher-order stages of cognitive processing related to selective attention. These results complement and extend previous work on the role of self-relevance in the selection of material for further processing.

Depression, rumination and the default network

Major depressive disorder (MDD) has been characterized by excessive default-network activation and connectivity with the subgenual cingulate. These hyper-connectivities are often interpreted as reflecting rumination, where MDDs perseverate on negative, self-referential thoughts. However, the relationship between connectivity and rumination has not been established. Furthermore, previous research has not examined how connectivity with the subgenual cingulate differs when individuals are engaged in a task or not. The purpose of the present study was to examine connectivity of the default network specifically in the subgenual cingulate both on- and off-task, and to examine the relationship between connectivity and rumination. Analyses using a seed-based connectivity approach revealed that MDDs show more neural functional connectivity between the posterior-cingulate cortex and the subgenual-cingulate cortex than healthy individuals during rest periods, but not during task engagement. Importantly, these rest-period connectivities correlated with behavioral measures of rumination and brooding, but not reflection.

Framing effects in judgment tasks with varying amounts of information

Abstract Subjects were asked to make evaluations in each of three tasks—a gambling task, a consumer judgment task, and a student evaluation task. Each task involved two important attributes, but information about one attribute was missing on some trials. Half of the subjects received a version of the task in which a key attribute was presented in positive terms (e.g., probability of winning a gamble) and half received a version in which that same attribute was presented in negative terms (e.g., probability of losing a gamble). Even though the information was objectively equivalent in the two versions of each task, there were two significant framing effects. (1) In all tasks, responses to two-attribute stimuli were more favorable in the positive condition than in the negative condition. (2) When the key attribute was missing, evaluations of one-attribute stimuli relative to evaluations of two-attribute stimuli were lower in the positive condition than in the negative condition. Results were discussed in terms of the constructs of prospect theory and information integration theory.

Right-posterior face processing anomaly in depression.

Evidence of a right-posterior brain anomaly was found in a study of 19 individuals with major depression and 15 controls. Participants performed a recognition-memory task involving positive, neutral, and negative face and word stimuli. Scalp brain wave topography suggested a region-specific anomaly in the depressed group. Individuals with major depression demonstrated a reduction in the N200 component of the event-related brain potential to faces and not words. Furthermore, results indicate that the regional anomaly is specific to positive facial stimuli. Findings are interpreted in light of a model of regional brain specialization in emotion and psychopathology.

Neural and behavioral effects of interference resolution in depression and rumination

Individuals diagnosed with major depressive disorder (MDD) often ruminate about their depression and their life situations, impairing their concentration and performance on daily tasks. We examined whether rumination might be due to a deficit in the ability to expel negative information from short-term memory (STM), and fMRI was used to examine the neural structures involved in this ability. MDD and healthy control (HC) participants were tested using a directed-forgetting procedure in a short-term item recognition task. As predicted, MDD participants had more difficulty than did HCs in expelling negative, but not positive, words from STM. Overall, the neural networks involved in directed forgetting were similar for both groups, but the MDDs exhibited more spatial variability in activation in the left inferior frontal gyrus (a region critical for inhibiting irrelevant information), which may contribute to their relative inability to inhibit negative information.

Framing effects in decisions with completely and incompletely described alternatives

Earlier research has shown that a variety of judgments depend upon how key sources of information are framed. Framing effects have been extended to include relative evaluations of stimuli with complete and incomplete information. The present study was designed to see if these effects are predictive of discrete choices and to isolate the locus of the framing effect. In Experiment 1 subjects were asked to indicate whether they would take each of a series of gambles described by payoff and probability information or by only one of these values. As predicted, subjects in the positive condition were more apt than subjects in the negative condition to take gambles when probability information was included, but not when it was missing. Subjects in Experiment 2 chose between gambles with complete and incomplete information. Consistent with the earlier findings, subjects in the positive condition were less apt than subjects in the negative condition to choose the gamble with missing probability information. Experiment 3 replicated the results of Experiment 2 while eliminating various psychophysical factors as causes of the framing effect. The way stimuli are framed appears to affect their subjective scale values and this determines both how they are responded to in an absolute sense and how they are compared to other stimuli.

Reduced sustained brain activity during processing of positive emotional stimuli in major depression.

BACKGROUND This study examines the directionality and temporal specificity of brain activity during sustained processing of emotional stimuli in individuals with current major depressive disorder (MDD) and nondepressed control participants. METHODS Slow wave (SW) components of the event-related brain potential (ERP) were recorded from 16 control participants and 15 participants with MDD during a working memory task. During the task, individuals were shown a positive, neutral, or negative word and were asked to maintain it in memory for 5 sec. Participants then saw a letter and had to decide whether it was a part of the previously presented word. The ERP components were measured from nine scalp sites (F3, Fz, F4, C3, Cz, C4, P3, Pz, P4) during the encoding of emotional words. RESULTS Compared with control individuals, MDD participants exhibited decreased brain responses to positive relative to negative or neutral stimuli. This decrease in brain activity during processing of positive information was evident across all sites and SW components. CONCLUSIONS Our findings suggest that cognitive deficits in MDD may stem from diminished brain responses during processing of positive information and may not be associated with an augmented response to negative stimuli.

Cognitive bias and emotion in neuropsychological models of depression

Neuropsychological models of depression were tested by examining encoding and recognition biases elicited by emotional stimuli manifested in regional brain wave activity. Participants were pre-exposed to emotional stimuli. These stimuli were presented again embedded in new stimuli, and event-related brain potentials (ERPs) were recorded while participants judged whether they had viewed each stimulus previously. Controls showed an enhanced P300 during encoding and reduced P300 during recognition of positive stimuli, indicating a response bias for positive information. In contrast, participants diagnosed with major depression showed no valence difference during encoding of new stimuli or recognition of old stimuli. These results suggest positive cognitive biases in controls and a lack of such a biases in depressed individuals. Additionally, regression analyses demonstrated that a substantial proportion of P300 variance was related to clinical scale

A preliminary investigation of cognitive flexibility for emotional information in major depressive disorder and non-psychiatric controls.

Clinical research suggests that individuals with major depressive disorder (MDD) are cognitively inflexible, exhibiting ruminative, rigid, and automatic thoughts within a negative schema. However, existing neuropsychological research on cognitive flexibility in this population has not employed emotional stimuli. Because research suggests that the performance of individuals with MDD is modulated when emotional stimuli are used, this study investigates the impact of emotional stimuli on cognitive flexibility performance through a novel emotional modification of the Wisconsin Card Sorting Test. Controls were less flexible when stimuli were positive and individuals with MDD were less flexible when stimuli were negative relative to the controls. These divergent styles of responding to emotional information may contribute to the relative risk or protection from depressed mood.

Memory of Faces: A Slow Wave ERP Study of Major Depression

This study examined slow wave (SW) event-related brain potential (ERP) amplitudes in response to happy, neutral, and sad faces during a working memory task to further identify the associated component processes and physiological changes of mood-congruent memory biases in individuals with and without major depression. The results suggest that individuals with and without a diagnosis of major depressive disorder (MDD) differentially maintain valenced facial information in their working memory. Specifically, the nondepressed individuals displayed a marked reduction in SW amplitude to the negative faces. Individuals with MDD exhibited equivalent SW amplitudes for positive and negative facial stimuli. Results are discussed in terms of avoidance coping, previous ERP studies of working memory, and facial recognition deficits in individuals with MDD.