Mood-congruent Memory Bias Research Articles

Sad expressions during encoding enhance facial identity recognition in visual working memory in depression: Behavioural and electrophysiological evidence

Background: Mood-congruent memory biases are prominently featured in cognitive theories of depression. However, how sad expressions during encoding affect facial identity recognition in visual working memory (WM) and the electrophysiological correlates in depressed individuals are unclear.Methods: Event-related potentials (ERPs) were recorded from 30 depressed participants and 31 controls during a delayed face discrimination task.Results: The depressed participants showed lower discrimination power in facial identity recognition than the controls. However, the depressed participants showed higher discrimination power in facial identity recognition for neutral probe faces preceded by sad expressions than for those preceded by happy expressions, while the controls showed no difference. Furthermore, hits (correctly recognizing studied faces) and associated vertex positive potential (VPP), P3b, and late positive potential (LPP) amplitudes were significantly higher for probe faces preceded by sad expressions than for those preceded by happy expressions in the depressed individuals, whereas the controls showed no differences. No such effects were found for correct rejections (correctly rejecting unstudied faces).Limitations: The present study is limited due to the relatively small sample size and homogenous university population.Conclusions: The findings suggest that for depressed individuals, sad expressions during encoding enhanced discrimination power in facial identity recognition, especially correct recognition of studied faces in visual WM, which was associated with an increase in early structural encoding and more late attentional and perceptual resources following facial identity during retrieval, reflecting a mood-congruent memory bias.

Implicit Mood Congruent Memory Bias in Subclinical Depression

Prior literature reports that the activation of conceptual processing is necessary, albeit insufficient, for the detection of implicit mood congruent memory bias. The purpose of this research was to investigate the effects of self-referential processing on this bias in individuals with subclinical depression. Two groups of participants (subclinical depressed vs. non-depressed) were given a perceptive or conceptual implicit memory task involving adjectives that varied in terms of their emotional valence and the manner in which they had been encoded. Our main finding was that those individuals with subclinical depression recorded a bias in the conceptual task, but only when they had encoded the content in a more self-referential manner. The findings are consistent with the activation of cognitive self-schema during the processing of emotional information of a self-referential nature in subclinical depression.

A novel task to assess mood congruent memory bias in non-human animals

BackgroundAssessing the affective state of animals is important for a range of research areas, including neuroscience. The use of cognitive judgement and attention biases to determine affective state has been demonstrated in animals, but approaches to assess mood-congruent biases in memory have yet to become established. New MethodWe describe a novel methodology to investigate memory bias in animals, presenting initial data using the influence of social status to manipulate affective state. The method required laboratory rats to achieve criterion at a working-memory task in an eight-arm radial maze before probing their memory of putative negative, positive or neutral events that occurred in specific arms of the maze. They were tested 2 h and 24 h after experiencing each event to determine how the affective valence of the event influenced task performance. ResultsRegardless of social status, rats avoided arms where they had experienced negative events and preferred arms where they had experienced positive events. However, subordinate rats made errors sooner than dominant rats in tests following exposure to the negative event. Furthermore, whilst subordinate individuals made errors earlier in tests following the negative event relative to the neutral or positive event, dominant rats made errors earlier in tests that followed the positive event. Comparison with existing method(s)Changes in performance thus appeared to reflect social status and associated affective state, confirming a new method for assessing animal affect. ConclusionsThis new memory bias task could potentially be used to determine affective state in a range of non-human animal species.

Relationship between cardiac vagal activity and mood congruent memory bias in major depression

BackgroundPrevious studies suggest that autonomic reactivity during encoding of emotional information could modulate the neural processes mediating mood-congruent memory. In this study, we use a point-process model to determine dynamic autonomic tone in response to negative emotions and its influence on long-term memory of major depressed subjects. MethodsForty-eight patients with major depression and 48 healthy controls were randomly assigned to either neutral or emotionally arousing audiovisual stimuli. An adaptive point-process algorithm was applied to compute instantaneous estimates of the spectral components of heart rate variability [Low frequency (LF), 0.04–0.15Hz; High frequency (HF), 0.15–0.4Hz]. Three days later subjects were submitted to a recall test. ResultsA significant increase in HF power was observed in depressed subjects in response to the emotionally arousing stimulus (p=0.03). The results of a multivariate analysis revealed that the HF power during the emotional segment of the stimulus was independently associated with the score of the recall test in depressed subjects, after adjusting for age, gender and educational level (Coef. 0.003, 95%CI, 0.0009–0.005, p=0.008). LimitationsThese results could only be interpreted as responses to elicitation of specific negative emotions, the relationship between HF changes and encoding/recall of positive stimuli should be further examined. ConclusionsAlterations on parasympathetic response to emotion are involved in the mood-congruent cognitive bias observed in major depression. These findings are clinically relevant because it could constitute the mechanism by which depressed patients maintain maladaptive patterns of negative information processing that trigger and sustain depressed mood.

Short-Term Duloxetine Administration Affects Neural Correlates of Mood-Congruent Memory

It is unknown how antidepressants reverse mood-congruent memory bias, a cognitive core factor causing and maintaining depression. Using a double-blind, placebo-controlled, cross-over design, we investigated the effect of a short-term treatment (14 days) with the dual reuptake inhibitor duloxetine on neural correlates of mood-congruent and mood-incongruent memory formation and retrieval in healthy volunteers who underwent a sad mood induction procedure. Duloxetine did not affect acute mood state or memory performance, but interacted with brain processes mediating mood-congruent memory. It decreased activity related to successful memory formation for mood-congruent and -incongruent items in a set of brain regions comprising the putamen and the middle frontal gyrus, as well as the middle and the anterior cingulate cortex. Duloxetine specifically increased amygdala activity related to successful memory retrieval for mood-incongruent items. Here we show that short-term administration of duloxetine affects the neural correlates of emotional memory formation and retrieval in a set of brain regions whose processing is related to affective state and its regulation. While duloxetine suppressed the neural correlates of emotional memory formation in general, it specifically enhanced amygdala processes associated with mood-incongruent memory retrieval. This pattern of results shows how an antidepressant may reduce emotional memory formation and reverse mood-congruent processing biases at retrieval.

How mood challenges emotional memory formation: An fMRI investigation

Experimental mood manipulations and functional magnetic resonance imaging (fMRI) provide a unique opportunity for examining the neural correlates of mood-congruent memory formation. While prior studies in mood-disorder patients point to the medial temporal lobe in the genesis of mood-congruent memory (MCM) bias, the interaction between mood and emotional memory formation has not been investigated in healthy participants. In particular it remains unclear how regulatory structures in the pre-frontal cortex may be involved in mediating this phenomenon. In this study, event-related fMRI was performed on 20 healthy participants using a full-factorial, within-subjects repeated-measures design to examine how happy and sad moods impact memory for valenced stimuli (positive, negative and neutral words). Main effects of mood, stimulus valence and memory were examined as was activity related to successful memory formation during congruent and in-congruent moods. Behavioral results confirm an MCM bias while imaging results show amygdala and hippocampal engagement in a global mood and successful recall, respectively. MCM formation was characterized by increased activity during mood-congruent encoding of negative words in the orbito-frontal cortex (OFC) and for mood-incongruent processing of negative words in medial- and inferior-frontal gyri (MFG/IFG). These findings indicate that different pre-frontal regions facilitate mood-congruent and incongruent encoding of successfully recalled negative words at the time of learning, with OFC enhancing congruency and the left IFG and MFG helping overcome semantic incongruities between mood and stimulus valence.

Attentional biases in dysphoria: An eye-tracking study of the allocation and disengagement of attention

This study looked for evidence of biases in the allocation and disengagement of attention in dysphoric individuals. Participants studied images for a recognition memory test while their eye fixations were tracked and recorded. Four image types were presented (depression-related, anxiety-related, positive, neutral) in each of two study conditions. For the simultaneous study condition, four images (one of each type) were presented simultaneously for 10 seconds, and the number of fixations and the total fixation time to each image was measured, similar to the procedure used by Eizenman et al. (2003) and Kellough, Beevers, Ellis, and Wells (2008). For the sequential study condition, four images (one of each type) were presented consecutively, each for 4 seconds; to measure disengagement of attention an endogenous cuing procedure was used (Posner, 1980). Dysphoric individuals spent significantly less time attending to positive images than non-dysphoric individuals, but there were no group differences in attention to depression-related images. There was also no evidence of a dysphoria-related bias in initial shifts of attention. With respect to the disengagement of attention, dysphoric individuals were slower to disengage their attention from depression-related images. The recognition memory data showed that dysphoric individuals had poorer memory for emotional images, but there was no evidence of a conventional mood-congruent memory bias. Differences in the attentional and memory biases observed in depressed and dysphoric individuals are discussed.

PATHOPHYSIOLOGY OF DEPRESSION: DO WE HAVE ANY SOLID EVIDENCE OF INTEREST TO CLINICIANS?

Due to the clinical and etiological heterogeneity of major depressive disorder, it has been difficult to elucidate its pathophysiology. Current neurobiological theories with the most valid empirical foundation and the highest clinical relevance are reviewed with respect to their strengths and weaknesses. The selected theories are based on studies investigating psychosocial stress and stress hormones, neurotransmitters such as serotonin, norepinephrine, dopamine, glutamate and gamma-aminobutyric acid (GABA), neurocircuitry, neurotrophic factors, and circadian rhythms. Because all theories of depression apply to only some types of depressed patients but not others, and because depressive pathophysiology may vary considerably across the course of illness, the current extant knowledge argues against a unified hypothesis of depression. As a consequence, antidepressant treatments, including psychological and biological approaches, should be tailored for individual patients and disease states. Individual depression hypotheses based on neurobiological knowledge are discussed in terms of their interest to both clinicians in daily practice and clinical researchers developing novel therapies.

Memory for emotional faces in major depression following judgement of physical facial characteristics at encoding

The aim of the present study was to establish if patients with major depression (MD) exhibit a memory bias for sad faces, relative to happy and neutral, when the affective element of the faces is not explicitly processed at encoding. To this end, 16 psychiatric out-patients with MD and 18 healthy, never-depressed controls (HC) were presented with a series of emotional faces and were required to identify the gender of the individuals featured in the photographs. Participants were subsequently given a recognition memory test for these faces. At encoding, patients with MD exhibited a non-significant tendency towards slower gender identification (GI) times, relative to HC, for happy faces. However, the GI times of the two groups did not differ for sad or neutral faces. At memory testing, patients with MD did not exhibit the expected memory bias for sad faces. Similarly, HC did not demonstrate enhanced memory for happy faces. Overall, patients with MD were impaired in their memory for the faces relative to the HC. The current findings are consistent with the proposal that mood-congruent memory biases are contingent upon explicit processing of the emotional element of the to-be-remembered material at encoding.

When the half-full glass is appraised as half empty and memorised as completely empty: Mood-congruent true and false recognition in depression is modulated by salience

Since the 1980s a large body of empirical effort has been devoted to mood-congruent memory (MCM) biases in clinical depression. Whereas there is broad, albeit not unequivocal, evidence that depressive patients retain negative-valenced memory items better than neutral material, few studies have investigated false memories in depression. In a pilot study we gathered support for both enhanced true and false memory for emotional material in depression. The present study aimed to extend these preliminary findings. In view of investigations suggesting that arousing and meaningful stimuli have facilitated access to memory, personal salience was considered a moderator for MCM. In the present study 21 depressed and 22 healthy participants were presented six false memory lists dealing with neutral, negative, and positive themes. At recognition, each item had to be appraised for its degree of valence subsequent to an old–new judgement. Pre-categorised and subjective valence did not discriminate groups. However, relative to controls depressed patients showed both more veridical as well as false recognition for items that concurrently elicited higher salience ratings in patients. In contrast, group differences in recognition performance did not significantly affect salience ratings. Results indicate that salience modulates MCM and may account for discrepancies in the literature.

Recollective Experience During Recognition of Emotional Words in Clinical Depression

Earlier work has shown that free recall tasks produce a robust mood-congruent memory effect in depression, whereas recognition tasks produce heterogeneous results. This study aimed to further investigate recognition memory for positive, negative and neutral words in depressed patients and matched comparison participants with the Remember/Know/Guess procedure for assessing recollection and familiarity. No mood-congruent memory bias effect was detected in discrimination abilities. However, depressed patients recollected (more Remember responses) more negative than positive or neutral words, whereas comparison participants recollected more positive than neutral words. No mood-congruent pattern was evidenced for Know responses. However, the depressed patients responded to fewer words overall with Know responses than the comparison participants. These results suggest that the mood-congruent memory pattern in depressed patients is related to conscious recollection rather than to familiarity. Attentional biases toward negative words and elaboration processes and/or encoding in reference to the self may contribute to these findings.

Investigation of mood-congruent false and true memory recognition in depression

The present study investigated the extent of mood-congruent false and true memory recognition in depression. A group of 25 patients with depression and 28 healthy controls completed a variant of the Deese-Roediger McDermott task. Four lists were read to participants in sequence, followed by a recognition task. The words in each list were associated with a central but unmentioned theme word that was either depression-relevant (i.e., loneliness), delusion-relevant (betrayal), positive (holidays), or neutral (window). Whereas it was expected to replicate the conventional mood-congruent effect in depression (better recognition of depression-relevant items), the available literature did not allow strong predictions to be made on the extent of mood-congruent false recognition in depression. Results showed that depressed patients learned emotionally charged material equally well as healthy participants but forgot significantly more neutral material. A conventional mood-congruent memory bias was not found, but relative to healthy controls, patients with depression committed more false recognition errors for emotionally charged words, particularly for depression-relevant items. The results confirm that depressed patients are biased toward emotional material. Reasons for the absence of the expected mood-congruent memory bias are discussed. It is suggested that researchers as well as clinicians should pay more attention to mood-congruent false recollection, because it may undermine the validity of autobiographic reports in depressive patients and may represent a maintenance factor for the disorder.

Depression and Implicit Memory: Understanding Mood Congruent Memory Bias

The present paper reviews the depression and implicit memory literature, emphasizing studies addressing possible mood congruent implicit memory biases in depression. Although some of these studies seem to indicate the presence of mood congruent biases in implicit memory, others fail to show this effect. Although the studies differ on a variety of dimensions (participant population, sample size, implicit memory task, depressive status, etc.), a thorough review of the literature suggests that these are not the most important considerations in understanding the presence or absence of mood congruent memory biases in depression. Rather, the cognitive framework of Transfer Appropriate Processing is used as a tool to organize and explain these findings. In particular, the role of perceptual and conceptual cognitive processes by depressed participants performing implicit memory tasks are examined in the context of perceptual and conceptual task demands. Examining unconscious influences on emotion could have important implications for understanding and treating depression.

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.

Selective memory and memory deficits in depressed inpatients.

We investigated memory impairment and mood-congruent memory bias in depression, using an explicit memory test and an implicit one. Thirty-six severely depressed inpatients that fulfilled DSM-IV criteria for major depressive disorder and 36 healthy controls matched for sex, age, and educational level participated in the study. Explicit memory was assessed with a free recall task and implicit memory with an anagram solution task. Results showed that depressed and controls differed in explicit memory performance, depending on the amount of cognitive distraction between incidental learning and testing. Implicit memory was not affected. In addition, severely depressed patients showed a mood-congruent memory bias in implicit memory but not in explicit memory. The complex pattern of results is discussed with regard to relevant theories of depression.

Implicit memory bias in depression

In this review I describe research conducted in my laboratory concerning implicit mood-congruent memory (MCM) bias in clinical depression. MCM is the tendency for depressed individuals to retrieve more unpleasant information from memory than nondepressed controls, and may be an important maintenance mechanism in depression. MCM has been studied frequently with explicit memory tests, but relatively few studies have investigated MCM using implicit memory tests. I describe several implicit memory studies which show that: (a) an implicit MCM bias does not appear to exist when perceptually driven tests are used; (b) implicit memory bias can be found when conceptually driven tests are used, but (c) not all conceptually driven tests show implicit MCM bias. I conclude that conceptual processing is necessary, but is not sufficient for demonstrating implicit memory bias in depression. Future studies should investigate specific components of conceptual elaboration that support implicit memory bias in depression.

Explicit and implicit memory biases in depression and panic disorder

The purpose of the present study was to investigate the presence of a bias for emotional information (panic-related, depression-related, positive and neutral) in explicit memory and implicit memory (by means of free recall and word-stem completion tasks, respectively) among depressed ( N=20) and panic ( N=20) patients. Three different encoding conditions (graphemic, semantic and self-reference) were used. The results of this study failed to show the existence of a mood-congruent memory bias for both implicit and explicit memory in these emotional disorders. According to the correlational analyses performed, differences among categories of emotional words meant less than the difference among various types of encoding and memory bias in order to differentiate among groups.

Unconscious memory bias in depression: Perceptual and conceptual processes.

Mood-congruent memory (MCM) bias in depression was investigated using 4 different implicit memory tests. Two of the implicit tests were perceptually driven, and 2 were conceptually driven. Depressed participants and nondepressed controls were assigned to 1 of 4 implicit memory tests after studying positive and negative adjectives. Results showed no MCM bias in the perceptually driven tests. MCM was demonstrated in 1 of the conceptually driven tests, but only for adjectives that were conceptually encoded. Results support the theory that mood-congruent processes in depression are limited to conceptual processing. However, activation of conceptual processes may not be sufficient for demonstrating mood congruency.

On the Status of Implicit Memory Bias in Anxiety

The present study evaluated the status of mood-congruent memory bias in implicit memory tasks for threat-related information. A literature review complemented by three experiments on high and low trait anxiety participants found no implicit memory bias for threat-related information in anxious individuals on either word fragment completion or tachistoscopic word identification tasks. The theoretical implications of these results are discussed.

Anxiety and Mood-congruent Autobiographical Memory: A Conceptual Failure to Replicate

This study further explored whether highly anxious participants exhibit a mood-congruent autobiographical memory bias, as was found in two previous studies (Burke & Mathews, 1992; Richards & Whittaker, 1990). The 74 high and low trait anxious participants retrieved personal memories to anxiety-related, neutral, and positive cue words, and were then asked to recall the original cue words. The study also explored how expression of emotional versus factual responses might affect a memory bias. On most dependent measures, no differences were found between anxiety groups. However, low anxious participants recalled more memories overall than high anxious participants. In addition, the emotions groups recalled more words at free recall than the facts groups. Findings fail to support previous studies that found an autobiographical memory bias to be associated with high anxiety, and cast more support for the mounting evidence against a mood-congruent memory bias in anxiety.