Autobiographical memory (AM) refers to memory for events from our own personal past. Functional neuroimaging studies of AM are important because they can investigate the neural correlates of processes that are difficult to study using laboratory stimuli, including: complex constructive processes, subjective qualities of memory retrieval, and remote memory. Three functional magnetic resonance imaging (fMRI) studies are presented to examine these important contributions of AM. The first study investigates the neural correlates of temporal-order memory for autobiographical events using a novel photo paradigm. Participants took photographs at many campus locations over a period of several hours, and the following day they were scanned while making temporal-order judgments to pairs of photographs from different locations. It was found that temporal-order decisions associated with recollection recruited left prefrontal (PFC) and left posterior parahippocampal cortex, whereas temporal-order decisions relying on familiarity recruited greater activity in the right PFC.The second study examines self-projection, the capacity to re-experience the personal past and to mentally infer another person's perspective. A novel camera technology was used to examine self-projection by prospectively generating dynamic visuospatial images taken from a first-person perspective. Participants were literally asked to self-project into the personal past or into the life of another person. Selfv projection of one's own past self recruited greater ventral medial PFC (mPFC), and selfprojection of another individual recruited dorsal mPFC. Activity in ventral vs. dorsal mPFC was also sensitive to the ability to relive or understand the perspective taken on each trial. Further, task-related functional connectivity analysis revealed that ventral mPFC contributed to the medial temporal lobe network linked to memory processes, whereas dorsal mPFC contributed to the frontoparietal network linked to controlled processes.The third study focuses on the neural correlates underlying age-related differences in the recall of episodically rich AMs. Age-related attenuation in the episodic richness of AM was linked to reductions in activity elicited during elaboration.Age effects on AM were more pronounced during elaboration than search, with older adults showing less sustained recruitment of the hippocampus and ventrolateral PFC for less episodically rich AMs. Further, there was an age-related reduction in the top-down modulation of the PFC on the hippocampus by episodic richness, possibly reflecting fewer controlled processes operating on the recovery of information in the hippocampus.Ultimately, the goal of all memory research is to understand how memory operates in the real-world; the present research highlights the important contribution of functional neuroimaging studies of AM in attaining this goal.vi
Memory is prone to distortions that can have serious consequences in everyday life. Here we integrate emerging evidence that several types of memory distortions – imagination inflation, gist-based and associative memory errors, and post-event misinformation – reflect adaptive cognitive processes that contribute to the efficient functioning of memory, but produce distortions as a consequence of doing so. We consider recent cognitive and neuroimaging studies that link these distortions with adaptive processes, including simulation of future events, semantic and contextual encoding, creativity, and memory updating. We also discuss new evidence concerning factors that can influence the occurrence of memory distortions, such as sleep and retrieval conditions, as well as conceptual issues related to the development of an adaptive perspective.
Previous evidence has suggested both preserved emotional function in aging and age-related differences in emotional processing, but the neural networks underlying such processing alterations in the context of preserved affective function are not clear. Using event-related fMRI, we scanned young and older adults while they made valence ratings for emotional pictures. Behavioral results showed a similar pattern of emotional evaluation, but older adults experienced negatively valenced pictures as being less negative. Consistent with behavioral findings, we identified common activity in the right amygdala, but age-related differences in the functional connectivity of this region with the rest of the brain. Compared to young adults, older adults had greater functional connectivity between the right amygdala and ventral anterior cingulate cortex, possibly reflecting increased emotional regulation. Conversely, older adults showed decreased functional connectivity with posterior brain regions, likely reflecting decreased perceptual processing. Thus, age-related differences in evaluating negatively valenced stimuli might reflect decreased perceptual processing of these stimuli, as well as the engagement of control processes that inhibit the response to negative emotion.
We investigated age-related effects in recall of emotional and neutral autobiographical memories. Protocols were scored according to episodic and non-episodic detail categories using the Autobiographical Interview. Young adults recalled a greater number of episodic details compared to older adults, whereas older adults recalled more semantic details, replicating previous findings. Both young and older adults' emotional memories contained more overall detail than neutral ones, with the enhancement from emotion-specific to episodic details, but this did not alter the effect of age group on the pattern of episodic and semantic details. However, the age effect on episodic details was attenuated for neutral autobiographical memories. The findings suggest that age differences for emotional autobiographical recollection might reflect a more general pattern of age-related changes in memory, with impaired recall of episodic components and relative sparing of semantic aspects of autobiographical memory in older adults when compared to young adults.
How do separate neural networks interact to support complex cognitive processes such as remembrance of the personal past? Autobiographical memory (AM) retrieval recruits a consistent pattern of activation that potentially comprises multiple neural networks. However, it is unclear how such large-scale neural networks interact and are modulated by properties of the memory retrieval process. In the present functional MRI (fMRI) study, we combined independent component analysis (ICA) and dynamic causal modeling (DCM) to understand the neural networks supporting AM retrieval. ICA revealed four task-related components consistent with the previous literature: 1) Medial Prefrontal Cortex (PFC) Network, associated with self-referential processes, 2) Medial Temporal Lobe (MTL) Network, associated with memory, 3) Frontoparietal Network, associated with strategic search, and 4) Cingulooperculum Network, associated with goal maintenance. DCM analysis revealed that the medial PFC network drove activation within the system, consistent with the importance of this network to AM retrieval. Additionally, memory accessibility and recollection uniquely altered connectivity between these neural networks. Recollection modulated the influence of the medial PFC on the MTL network during elaboration, suggesting that greater connectivity among subsystems of the default network supports greater re-experience. In contrast, memory accessibility modulated the influence of frontoparietal and MTL networks on the medial PFC network, suggesting that ease of retrieval involves greater fluency among the multiple networks contributing to AM. These results show the integration between neural networks supporting AM retrieval and the modulation of network connectivity by behavior.
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