Neural correlates of autobiographical memory retrieval in children and adults

Autobiographical memory (AM) is a critically important form of memory for life events that undergoes substantial developmental changes from childhood to adulthood. Relatively little is known regarding the functional neural correlates of AM retrieval in children as assessed with fMRI, and how they may differ from adults. We investigated this question with 14 children ages 8–11 years and 14 adults ages 19–30 years, contrasting AM retrieval with semantic memory (SM) retrieval. During scanning, participants were cued by verbal prompts to retrieve previously selected recent AMs or to verify semantic properties of words. As predicted, both groups showed AM retrieval-related increased activation in regions implicated in prior studies, including bilateral hippocampus, and prefrontal, posterior cingulate, and parietal cortices. Adults showed greater activation in the hippocampal/parahippocampal region as well as prefrontal and parietal cortex, relative to children; age-related differences were most prominent in the first 8?sec versus the second 8?sec of AM retrieval and when AM retrieval was contrasted with semantic retrieval. This study is the first to characterise similarities and differences during AM retrieval in children and adults using fMRI.     

Investigating virtual reality navigation in amnestic mild cognitive impairment using fMRI

Spatial navigation requires a well-established network of brain regions, including the hippocampus, caudate nucleus, and retrosplenial cortex. Amnestic Mild Cognitive Impairment (aMCI) is a condition with predominantly memory impairment, conferring a high predictive risk factor for dementia. aMCI is associated with hippocampal atrophy and subtle deficits in spatial navigation. We present the first use of a functional Magnetic Resonance Imaging (fMRI) navigation task in aMCI, using a virtual reality analog of the Radial Arm Maze. Compared with controls, aMCI patients showed reduced activity in the hippocampus bilaterally, retrosplenial cortex, and left dorsolateral prefrontal cortex. Reduced activation in key areas for successful navigation, as well as additional regions, was found alongside relatively normal task performance. Results also revealed increased activity in the right dorsolateral prefrontal cortex in aMCI patients, which may reflect compensation for reduced activations elsewhere. These data support suggestions that fMRI spatial navigation tasks may be useful for staging of progression in MCI.     

Role of anxiety and brooding in specificity of autobiographical recall

Overgeneral schemas and lack of autobiographical memory (AM) specificity about our past experiences can predict mood disturbance. Rumination, functional avoidance and executive processes are the main explanatory variables of such overgenerality. However, in non‐clinical samples, rumination predicts overgenerality most consistently after the induction of dysphoric mood. Anxiety also activates rumination. Furthermore, anxiety predicts memory performance and has effects on mood which are independent of the effects of rumination. So, what might be the role of anxiety in autobiographical memory performance? A sample of 210 voluntary participants reported measures of autobiographical memory, anxiety, rumination (brooding and reflection), functional avoidance and executive functions (semantic and phonetic verbal fluency task). Autobiographical performance (specificity) was negatively associated with brooding and age and positively with phonetic verbal fluency but not with functional avoidance and anxiety. However, anxiety and brooding were positively correlated even after controlling for depression scores. Moreover, using structural equation modeling, anxiety showed a significant indirect effect on autobiographical specificity through brooding rumination. These results suggest a possible association of anxiety with autobiographical recall through brooding rumination.     

Lateral and medial prefrontal contributions to emotion generation by semantic elaboration during episodic encoding

Memories for emotion-laden stimuli are remembered more accurately than those for neutral stimuli. Although this enhancement reflects stimulus-driven modulation of memory by emotions, functional neuroimaging evidence of the interacting mechanisms between emotions generated by intentional processes, such as semantic elaboration, and memory is scarce. The present fMRI study investigated how encoding-related activation is modulated by emotions generated during the process of semantic elaboration. During encoding with fMRI, healthy young adults viewed neutral (target) pictures either passively or with semantic elaboration. In semantic elaboration, participants imagined background stories related to the pictures. Encoding trials with semantic elaboration were subdivided into conditions in which participants imagined negative, positive, or neutral stories. One week later, memories for target pictures were tested. In behavioral results, memories for target pictures were significantly enhanced by semantic elaboration, compared to passive viewing, and the memory enhancement was more remarkable when negative or positive stories were imagined. fMRI results demonstrated that activations in the left inferior frontal gyrus and dorsal medial prefrontal cortex (dmPFC) were greater during the encoding of target pictures with semantic elaboration than those with passive viewing, and that these activations further increased during encoding with semantic elaboration of emotional stories than of neutral stories. Functional connectivity between the left inferior frontal gyrus and dmPFC/hippocampus during encoding significantly predicted retrieval accuracies of memories encoded with self-generated emotional stories. These findings suggest that networks including the left inferior frontal region, dmPFC, and hippocampus could contribute to the modulation of memories encoded with the emotion generation.     

Functional brain organization of working memory in adolescents varies in relation to family income and academic achievement

Working memory (WM) capacity reflects executive functions associated with performance on a wide range of cognitive tasks and education outcomes, including mathematics achievement, and is associated with dorsolateral prefrontal and parietal cortices. Here we asked if family income is associated with variation in the functional brain organization of WM capacity among adolescents, and whether that variation is associated with performance on a statewide test of academic achievement in mathematics. Participants were classified into higher‐income and lower‐income groups based on family income, and performed a WM task with a parametric manipulation of WM load (N‐back task) during functional magnetic resonance imaging (fMRI). Behaviorally, the higher‐income group had greater WM capacity and higher mathematics achievement scores. Neurally, the higher‐income group showed greater activation as a function of WM load in bilateral prefrontal, parietal, and other regions, although the lower‐income group exhibited greater activation at the lowest load. Both groups exhibited positive correlations between parietal activations and mathematics achievement scores, but only the higher‐income group exhibited a positive correlation between prefrontal activations and mathematics scores. Most of these findings were maintained when higher‐ and lower‐income groups were matched on WM task performance or nonverbal IQ. Findings indicate that the functional neural architecture of WM varies with family income and is associated with education measures of mathematics achievement.     

Field perspective deficit for positive memories characterizes autobiographical memory in euthymic depressed patients

Research on autobiographical memory (AM) and the ability to retrieve specific autobiographical events in euthymic depressed patients yielded divergent results. The main goal of the present study was to further explore episodic specificity of AM among fully remitted depressed patients. Twenty euthymic depressed patients and 20 matched healthy controls were given a semi-structured interview, which assesses episodic specificity of positive and negative autobiographical memories regarding event and details' specificity, autonoetic consciousness (remember/know procedure) and visual perspective (field/observer procedure). Results showed an impairment of episodic specificity of AM in euthymic depressed patients. This impairment was explained by a field perspective deficit for positive memories only. These results suggest that euthymic patients continue to exhibit discrepancy between their current self and their self for positive past behaviors, which maintains an unfavorable view of their current self. Specific cognitive interventions may improve the self-relevance of their positive memories.     

The effects of mindfulness on executive processes and autobiographical memory specificity

Previous studies have found that mindfulness training reduces overgeneral memories and increases autobiographical memory specificity (e.g., [Williams, J. M. G., Teasdale, J. D., Segal, Z. V., & Soulsby, J. (2000). Mindfulness-based cognitive therapy reduces overgeneral autobiographical memory in formerly depressed patients. Journal of Abnormal Psychology, 109, 150-155]). However, little work has investigated the mechanisms underlying this effect. The present study explored the role of executive processes as a mediator of MBCT effects in an unselected sample. An autobiographical memory task, a cognitive inhibition task, a motor inhibition task, a cognitive flexibility task and a motor flexibility task were administered before and after intervention. Compared to matched controls, MBCT participants showed increased autobiographical memory specificity, decreased overgenerality, and improved cognitive flexibility capacity and capacity to inhibit cognitive prepotent responses. Mediational analyses indicated that changes in cognitive flexibility partially mediate the impact of MBCT on overgeneral memories. Results are discussed in terms of Conway's [2005. Memory and the self. Journal of Memory and Language, 53, 594-628] autobiographical memory model.     

Bi-hemispheric engagement in the retrieval of autobiographical episodes

Functional magnetic resonance imaging (fMRI) was used to study the neural correlates of neutral, stressful, negative and positive autobiographical memories. The brain activity produced by these different kinds of episodic memory did not differ significantly, but a common pattern of activation for different kinds of autobiographical memory was revealed that included (1) largely bilateral portions of the medial and superior temporal lobes, hippocampus and parahippocampus, (2) portions of the ventral, medial, superior and dorsolateral prefrontal cortex, (3) the anterior and posterior cingulate, including the retrosplenial, cortex, (4) the parietal cortex, and (5) portions of the cerebellum. The brain regions that were mainly activated constituted an interactive network of temporal and prefrontal areas associated with structures of the extended limbic system. The main bilateral activations with left-sided preponderance probably reflected reactivation of complex semantic and episodic self-related information representations that included previously experienced contexts. In conclusion, the earlier view of a strict left versus right prefrontal laterality in the retrieval of semantic as opposed to episodic autobiographical memory, may have to be modified by considering contextual variables such as task demands and subject variables. Consequently, autobiographical memory integration should be viewed as based on distributed bi-hemispheric neural networks supporting multi-modal, emotionally coloured components of personal episodes.     

Target-related autobiographical memories affect dietary intake intentions*

ABSTRACT

Although there is evidence that autobiographical memory (AM) recall impacts behaviour in multiple domains, the mechanisms for this effect are unclear. Two experiments examined how AM Frame and Relatedness to target behaviour affect intention to control future dietary intake. Participants completed an AM task where they recalled success or fail-framed memories of behaviour in the target domain (dietary intake), a related domain (exercise), and an unrelated domain (work). Next they completed questionnaires about attitudes, self-efficacy, and behavioural intention for controlling dietary intake. In Experiment 1, Frame and Relatedness of AMs recalled did not affect attitudes or self-efficacy ratings of controlling dietary intake. However, Related AMs resulted in higher intention ratings to control future dietary intake compared to Unrelated AMs. Experiment 2 replicated these results for attitude and self-efficacy, but showed no effect on behavioural intention. A mini-meta analysis was conducted to clarify the effect of AM recall on intention. This analysis confirmed a significant effect of AM Relatedness on intention ratings (meta-analysis Cohen’s d?=?.25, Z?=?2.54, p?=?.011). These results provide evidence that recalling related AM can affect dietary behaviour intentions directly, without changes attitudes or ratings of personal control regarding dietary intake.     

Differentiating core and co-opted mechanisms in calculation: The neuroimaging of calculation in aphasia

The role of language in exact calculation is the subject of debate. Some behavioral and functional neuroimaging investigations of healthy participants suggest that calculation requires language resources. However, there are also reports of individuals with severe aphasic language impairment who retain calculation ability. One possibility in resolving these discordant findings is that the neural basis of calculation has undergone significant reorganization in aphasic calculators. Using fMRI, we examined brain activations associated with exact addition and subtraction in two patients with severe agrammatic aphasia and retained calculation ability. Behavior and brain activations during two-digit addition and subtraction were compared to those of a group of 11 healthy, age-matched controls. Behavioral results confirmed that both patients retained calculation ability. Imaging findings revealed individual differences in processing, but also a similar activation pattern across patients and controls in bilateral parietal cortices. Patients differed from controls in small areas of increased activation in peri-lesional regions, a shift from left fronto-temporal activation to the contralateral region, and increased activations in bilateral superior parietal regions. Our results suggest that bilateral parietal cortex represents the core of the calculation network and, while healthy controls may recruit language resources to support calculation, these mechanisms are not mandatory in adult cognition.     

Alterations in working memory networks in amnestic mild cognitive impairment

Patients with amnestic mild cognitive impairment (aMCI) show preserved or mildly impaired working memory, despite their deficits in episodic memory. We aimed to identify performance and/or neural differences between aMCI patients and matched controls on a standard working memory fMRI task. Neuropsychological assessment demonstrated aMCI impairments in verbal and visual episodic long-term memory, with intact IQ and executive function. Participants completed a standard three-level N-back task where patients were unimpaired. Functional activations in the control group were found in expected areas, including the inferior parietal lobule and dorsolateral prefrontal cortex. Group differences were found in the insula and lingual gyrus and, in a region of interest analysis, in the hippocampus. In all cases, these were caused by an absence of task-related deactivations in the aMCI group. The results are consistent with reports of failure in task-related deacivations in aMCI and could be early indications of pathology.     

The BOLD response during Stroop task-like inhibition paradigms: Effects of task difficulty and task-relevant modality

Previous studies of the Stroop task propose two key mediators: the prefrontal and cingulate cortices but hints exist of functional specialization within these regions. This study aimed to examine the effect of task modality upon the prefrontal and cingulate response by examining the response to colour, number, and shape Stroop tasks whilst BOLD fMRI images were acquired on a Siemens 3T MRI scanner. Behavioural analyses indicated facilitation and interference effects and a noticeable effect of task difficulty. Some modular effects of modality were observed in the prefrontal cortex that survived exclusion of task difficulty related activations. No effect of task-relevant information was observed in the anterior cingulate. Future comparisons of the mediation of selective attention need to consider the effects of task context and task difficulty.     

Interactions between the dorsal and the ventral pathways in mental rotation: An fMRI study

In this fMRI study, we examined the relationship between activations in the inferotemporal region (ventral pathway) and the parietal region (dorsal pathway), as well as in the prefrontal cortex (associated with working memory), in a modified mental rotation task. We manipulated figural complexity (simple vs. complex) to affect the figure recognition process (associated with the ventral pathway) and the amount of rotation (0° vs. 90°), typically associated with the dorsal pathway. The pattern of activation not only showed that both streams are affected by both manipulations, but also showed an overadditive interaction. The effect of figural complexity was greater for 90° rotation than for 0° in multiple regions, including the ventral, dorsal, and prefrontal regions. In addition, functional connectivity analyses on the correlations across the time courses of activation between regions of interest showed increased synchronization among multiple brain areas as task demand increased. The results indicate that both the dorsal and the ventral pathways show interactive effects of object and spatial processing, and they suggest that multiple regions interact to perform mental rotation.     

Functional Mobility in a Divided Attention Task in Older Adults With Cognitive Impairment

ABSTRACT. Motor disorders may occur in mild cognitive impairment (MCI) and at early stages of Alzheimer's disease (AD), particularly under divided attention conditions. We examined functional mobility in 104 older adults (42 with MCI, 26 with mild AD, and 36 cognitively healthy) using the Timed Up and Go test (TUG) under 4 experimental conditions: TUG single task, TUG plus a cognitive task, TUG plus a manual task, and TUG plus a cognitive and a manual task. Statistically significant differences in mean time of execution were found in all four experimental conditions when comparing MCI and controls (p < .001), and when comparing MCI and AD patients (p < .05). Receiver-operating characteristic curve analyses showed that all four testing conditions could differentiate the three groups (area under the curve > .8, p < .001 for MCI vs. controls; area under the curve > .7, p < .001 for MCI vs. AD). The authors conclude that functional motor deficits occurring in MCI can be assessed by the TUG test, in single or dual task modality.     

自传体记忆的情绪对其相关信息内隐提取的影响

本研究主要考察自传体记忆本身的情绪是否影响该记忆相关信息的内隐提取过程。取大学生15人完成实验, 实验分为两部分：记忆提取和词汇判断。首先在记忆提取阶段, 要求被试根据词对(形容词-中性名词)提取积极、消极和中性情绪色彩的自传体记忆事件。接着在词汇判断任务中, 要求被试对包含提取过记忆的中性名词的词语进行词和非词的判断, 并且记录相应的脑电波。结果发现：(1)被试按要求成功提取了积极、消极和中性三类自传体记忆事件。词汇判断任务中, 内隐提取三类自传体记忆信息的反应时和正确率均无显著差异。(2)相比于积极、中性自传体记忆信息, 消极自传体记忆信息提取的过程中的ERP波幅更大, 更偏向于正向。这表明自传体记忆信息的内隐提取受到记忆本身情绪的影响, 消极自传体记忆信息提取需要付出更多资源。     

The biology of visual perspective and depression: A reply to Sutin

A recent meta-analysis by Munafò, Durrant, Lewis, and Flint (2009) [Munafò, M. R., Durrant, C., Lewis, G., & Flint, J. (2009). Gene × environment interactions at the serotonin transporter locus. Biological Psychiatry, 65, 211–219] questioned the meaning of studies searching for endophenotypes associated with the serotonin-transporter-linked promoter region (5-HTTLPR) polymorphism, including our study on visual perspective during autobiographical memory retrieval. However, the association of 3rd person perspective with vulnerability for depression does not rely only on genetics. External consistency is provided by the influence of the 5-HTTLPR polymorphism on brain regions involved in emotion regulation and autobiographical memory retrieval (e.g. the medial prefrontal cortex). Internal consistency is provided by the increased prevalence of 3rd person perspective in both currently and previously depressed patients, as well as in depression-prone individuals. Further studies should examine therapeutic opportunities.     

Neural correlates of stimulus response and stimulus outcome shifting in healthy participants and MS patients

Introduction

Adaptation to changing situations can be mediated by two strategies: (1) Evaluation of a response and (2) Evaluation of outcome values in relation to objects. Previous studies indicate that response shifting is associated with a network comprising the left frontal cortex and parietal cortex connected by the superior longitudinal fascicle, whereas outcome evaluation is associated with a network consisting of the orbitofrontal cortex, amygdala and uncinate fascicle. However, these studies rarely compared both kinds of adaptation directly and existing fMRI studies with healthy subjects are not informative about the role of the two fiber systems.

Methods

We analyzed stimulus response shifting and stimulus outcome shifting in two studies, one fMRI-study on healthy participants and one study on patients with MS involving structural MRI (Diffusion Tensor Imaging, Voxel Based Morphometry, Ventricular volumetry). Two tasks were used, identical in presentation but different in instruction, controlling for effects of lower level processing. In the SRS task, participants had to perform a “Go” or “NoGo” response depending on a stimulus change: if the stimulus remained the same, they had to continue with the former type of response, if it changed they had to adapt their response pattern. In the SOS task they had to perform a “Go” response only if the presented stimulus corresponded to that of an internal alternating series.

Results

fMRI findings showed that SRS is related to a bilateral parietal-premotor network. In the left hemisphere the prefrontal cortex was also involved. SOS was lateralized to the right hemisphere, particularly to the anterior temporal pole and amygdala, and the inferior parietal cortex. MS patients impaired on this task suffered from lesions in the right uncinate fascicle and showed an enlarged right frontal lateral ventricle.

Conclusion

With physically identical tasks, a functional neuronal segregation can be demonstrated for stimulus response shifting (bilateral activations with a focus in the left prefrontal cortex) and stimulus outcome shifting (right anterior temporal lobe and right supramarginal gyrus).     

Attachment and autobiographical memory retrieval: Event-related potential evidence from strategic information processing

This article presents two studies using event-related potentials combined with an autobiographical memory (AM) retrieval task and a lexical judge task to explore differences in AM retrieval among differently attached individuals and to further explore whether the source of these differences is the schematic information processing mode or strategic information processing mode. The effectiveness of the information processing mode is also studied. The results revealed that differences in the AM extraction of different attachment styles were due to the strategic information processing mode, while no differences were found in the schematic information processing used by individuals with different attachment styles. Further, the strategic information processing used by the securely attached group was more flexible and efficient than that used by the insecurely attached group; moreover, the strategic information processing mode used by the avoidantly attached group was more stable and consistent than that used by the anxiously attached group.     

The effect of the order in which episodic autobiographical memories versus autobiographical knowledge are shared on feelings of closeness

Autobiographical memories (AMs) can be used to create and maintain closeness with others [Alea, N., &; Bluck, S. (2003). Why are you telling me that? A conceptual model of the social function of autobiographical memory. Memory, 11(2), 165–178]. However, the differential effects of memory specificity are not well established. Two studies with 148 participants tested whether the order in which autobiographical knowledge (AK) and specific episodic AM (EAM) are shared affects feelings of closeness. Participants read two memories hypothetically shared by each of four strangers. The strangers first shared either AK or an EAM, and then shared either AK or an EAM. Participants were randomly assigned to read either positive or negative AMs from the strangers. Findings suggest that people feel closer to those who share positive AMs in the same way they construct memories: starting with general and moving to specific.     

Identifying distinct sets of predictors of specific functions of autobiographical memory

ABSTRACT

Grounded in the ecological approach, research has charted several adaptive functions of autobiographical remembering. Each represents a rather different psychosocial domain (i.e., self, social, directive). The goal of this research was to determine the contributions of each of a set of variables, controlling for all others, in predicting use of autobiographical memory to serve each specific function. In two studies, participants (N?=?100; N?=?195) rated frequency of functional use of specific event memories and completed a brief battery of memory-related measures. Most Study One results were replicated in Study Two. Self-relevance of memories was related to their functional use regardless of domain. Each function was also, however, predicted by a unique set of variables consistent with its use in a given psychosocial domain. Findings emphasise how a combination of factors come into play to allow humans to use autobiographical memory to serve various different functions in navigating daily life.