Lifespan differences in hippocampal subregion connectivity patterns during movie watching.

Age-related episodic memory decline is attributed to functional alternations in the hippocampus. Less clear is how aging affects the functional connections of the hippocampus to the rest of the brain during episodic memory processing. We examined fMRI data from the CamCAN dataset, in which a large cohort of participants watched a movie (N = 643; 18-88 years), a proxy for naturalistic episodic memory encoding. We examined connectivity profiles across the lifespan both within the hippocampus (anterior, posterior), and between the hippocampal subregions and cortical networks. Aging was associated with reductions in contralateral (left, right) but not ipsilateral (anterior, posterior) hippocampal subregion connectivity. Aging was primarily associated with increased coupling between the anterior hippocampus and regions affiliated with Control, Dorsal Attention and Default Mode networks, yet decreased coupling between the posterior hippocampus and a selection of these regions. Differences in age-related hippocampal-cortical, but not within-hippocampus circuitry selectively predicted worse memory performance. Our findings comprehensively characterize hippocampal functional topography in relation to cognition in older age, suggesting that shifts in cortico-hippocampal connectivity may be sensitive markers of age-related episodic memory decline.

Shift happens: aging alters the content but not the organization of memory for complex events.

While cognitive aging research has compared episodic memory accuracy between younger and older adults, less work has described differences in how memories are encoded and recalled. This is important for memories of real-world experiences, since there is immense variability in which details can be accessed and organized into narratives. We investigated age effects on the organization and content of memory for complex events. In two independent samples (N = 45; 60), young and older adults encoded and recalled the same short-movie. We applied a novel scoring on the recollections to quantify recall accuracy, temporal organization (temporal contiguity, forward asymmetry), and content (perceptual, conceptual). No age-effects on recall accuracy nor on metrics of temporal organization emerged. Older adults provided more conceptual and non-episodic content, whereas younger adults reported a higher proportion of event-specific information. Our results indicate that age-related differences in episodic recall reflect distinctions in what details are assembled from the past.

Remembering what we imagine: the role of event schemas in shaping how imagined autobiographical events are recalled.

Much like recalling autobiographical memories, constructing imagined autobiographical events depends on episodic memory processes. The ability to imagine events contributes to several future-oriented behaviors (e.g., decision-making, problem solving), which relies, in part, on the ability to remember the imagined events. A factor affecting the memorability of such events is their adherence to event schemas-conceptualizations of how events generally unfold. In the current study, we examined how two aspects of event schemas-event expectancy and familiarity-affect the ability to recall imagined events. Participants first imagined and described in detail autobiographical events that either aligned with or deviated from an event, expected to occur in a context (e.g., a kitchen) that was either familiar or unfamiliar. This resulted in imaginations ranging from maximally schema-congruent (expected events in a familiar context) to maximally novel (unexpected events in an unfamiliar context). Twenty-four hours later, participants recalled these imagined events. Recollections were scored for the number of reinstated details from the imaginations and the number of newly added details. We found greater reinstatement of details for both the maximally congruent and maximally novel events, while maximally novel events were recalled more precisely than other events (i.e., fewer added details). Our results indicate a complementary benefit to remembering schematic and novel imagined events, which may guide equally important but distinct future-oriented behaviors.

The Neural Corelates of Constructing Conceptual and Perceptual Representations of Autobiographical Memories.

Contemporary neurocognitive frameworks propose that conceptual and perceptual content of autobiographical memories-personal past experiences-are processed by dissociable neural systems. Other work has proposed a central role of the anterior hippocampus in initially constructing autobiographical memories, regardless of the content. Here, we report on an fMRI study that utilized a repeated retrieval paradigm to test these ideas. In an MRI scanner, participants retrieved autobiographical memories at three timepoints. During the third retrieval, participants either shifted their focus to the conceptual content of the memory, the perceptual content of the memory, or retrieved the memory as they had done so on previous trials. We observed stronger anterior hippocampal activity for the first retrieval compared with later retrievals, regardless of whether there was a shift in content in those later trials. We also found evidence for separate cortical systems when constructing autobiographical memories with a focus on conceptual or perceptual content. Finally, we found that there was common engagement between later retrievals that required a shift toward conceptual content and the initial retrieval of a memory. This final finding was explored further with a behavioral experiment that provided evidence that focusing on conceptual content of a memory guides memory construction, whereas perceptual content adds precision to a memory. Together, these findings suggest there are distinct content-oriented cortical systems that work with the anterior hippocampus to construct representations of autobiographical memories.

Comparing neural activity during autobiographical memory retrieval between younger and older adults: An ALE meta-analysis.

Aging changes autobiographical memory (AM), yet the neural correlates of these changes are poorly understood, likely due to methodological variability across studies. We conducted a quantitative meta-analysis using activation likelihood estimation (GingerALE 3.0.2) to identify regions AM retrieval engaged in younger and older adults across 45 studies (Nyounger = 24 studies, 357 participants, 349 foci; Nolder = 21 studies, 299 participants, 356 foci), considering methodological differences in cueing AMs (i.e., using generic vs. specific/personalized cues). Both age-groups commonly engaged a left-lateralized pattern of brain activity that included the hippocampus, retrosplenial/posterior cingulate cortex, and angular gyrus. Younger adults showed enhanced right posterior cingulate cortical activity, while older adults presented with bilateral activity in the hippocampus, and enhanced activity in left middle temporal gyrus, precuneus, and retrosplenial cortex. Exploratory analyses indicated that age-related commonalties and differences in brain activity depended on the method of AM cuing. These findings suggest that key regions of AM retrieval are preserved in older age, yet subtle changes exist, especially depending on how AMs are cued.

Volume of the posterior hippocampus mediates age-related differences in spatial context memory and is correlated with increased activity in lateral frontal, parietal and occipital regions in healthy aging.

Healthy aging is associated with episodic memory decline, particularly in the ability to encode and retrieve object-context associations (context memory). Neuropsychological and neuroimaging studies have highlighted the importance of the medial temporal lobes (MTL) in supporting episodic memory across the lifespan. However, given the functional heterogeneity of the MTL, volumetric declines in distinct regions may impact performance on specific episodic memory tasks, and affect the function of the large-scale neurocognitive networks supporting episodic memory encoding and retrieval. In the current study, we investigated how MTL structure may mediate age-related differences in performance on spatial and temporal context memory tasks, in a sample of 125 healthy adults aged 19-76 years old. Standard T1-weighted MRIs were segmented into the perirhinal, entorhinal and parahippocampal cortices, as well as the anterior and posterior hippocampal subregions. We observed negative linear and quadratic associations between age and volume of the parahippocampal cortex, and anterior and posterior hippocampal subregions. We also found that volume of the posterior hippocampus fully mediated the association between age and spatial, but not temporal context memory performance. Further, we employed a multivariate behavior partial-least-squares analysis to assess how age and regional MTL volumes correlated with brain activity during the encoding and retrieval of spatial context memories. We found that greater activity within lateral prefrontal, parietal, and occipital regions, as well as within the anterior MTL was related to older age and smaller volume of the posterior hippocampus. Our results highlight the heterogeneity of MTL contributions to episodic memory across the lifespan and provide support for the posterior-anterior shift in aging, and scaffolding theory of aging and cognition.

The role of episodic memory in imagining autobiographical events: the influence of event expectancy and context familiarity.

Episodic memory plays a common role in constructing mental representations of past and imagined autobiographical events. Research has suggested that certain factors will affect how episodic memory is used during mental construction, such as the expectancy that an event will occur and the familiarity with an event's context. The aim of the current study was to understand how these factors affect episodic memory engagement and subjective experience during event imagination. In a within-subjects design, participants viewed context cues (high or low in familiarity), described imagined autobiographical events (expected or not expected to occur in these contexts) and rated their experience. 24-hours later, participants recalled and described the same events. We found that expectancy of the imagined events was associated with quicker access and increased episodic detail generation, regardless of context familiarity. Additionally, both event expectancy and context familiarity affected the subjective quality of the imagined events. Examining the episodic details in descriptions after the delay revealed comparable effects of these two factors. Our results underscore the importance of event expectancy in recruiting episodic memory for imagined autobiographical experiences.

Changes in the experience of time: The impact of spatial information on the perception and memory of duration.

Although it is understood that our experience of time is fluid and subjective, the cognitive mechanisms underlying this phenomenon are not well described. Based on event segmentation theory, we tested the hypothesis that changes in the context, particularly the spatial context, of an experience impact how an individual perceives (encodes) and remembers the length of that event. A group of participants viewed short videos of scenes from movies that either contained shifts in spatial context (e.g., characters moving through doorways) or did not contain any shifts in spatial context. In one task, participants estimated a randomly selected time duration (between 10 and 23 s) when encoding these videos. In a second task, the same participants estimated the duration of the videos after viewing them. We found that even though the presence of spatial shifts impacted how time was perceived, the nature of this effect differed as a function of task. Specifically, when time was estimated at encoding, these estimates were longer for videos that did not contain spatial shifts compared with those with spatial shifts. However, when these estimates were made at retrieval, durations were reported as longer for videos with spatial context shifts than those without. A second experiment replicated these main findings in a new sample. We interpret these results as providing new evidence for theories on how context changes, particularly those in spatial information, distort the experience of time differently during the encoding and retrieval phases of memory.

A Neurocognitive Perspective on the Forms and Functions of Autobiographical Memory Retrieval.

Autobiographical memory retrieval involves constructing mental representations of personal past episodes by associating together an array of details related to the retrieved event. This construction process occurs flexibly so that the event details can be associated together in different ways during retrieval. Here, we propose that differences in how this association occurs support a division in autobiographical remembering. We first review theories of autobiographical memory organization that suggest that episodic details of an experience are processed along a gradient of abstraction. This organization allows for the same autobiographical event to be recalled as either a conceptualized or perceptually-based episodic memory. We then use neuroimaging evidence to show how this division within episodic autobiographical memory is also present in the brain, both at a network level and within the hippocampus. Specifically, we suggest that the anterior and posterior hippocampus are obligatorily tuned towards constructing conceptual vs. perceptual episodic representations of autobiographical memories. Finally, we discuss the directive purpose of this proposed division of episodic remembering by reviewing decision scenarios that benefit from recalling the past as a conceptual vs. a perceptual episode. Conceptual remembering is useful to guide ambiguous decisions that have yet to be encountered whereas perceptual remembering is useful to guide decisions for well-structured tasks that have been previously experienced. We emphasize that the ability to shift between conceptual and perceptual forms of remembering, by virtue of hippocampal specialization, during decision-making and other memory-guided actions is the key to adaptive behavior.

An investigation of global-local processing bias in a large sample of typical individuals varying in autism traits.

Although individuals with an autism spectrum disorder display impaired function across several social and behavioral domains, they possess intact, and often superior visual processing abilities for local relative to global aspects of their visual environment. To address whether differences in visual processing similarly vary within typical individuals as a function of their level of social competence, using the Navon hierarchical figures task, here we examined the relationship between global-local visual processing style and the number of autism-like traits in a large sample of 434 typically developed persons. In line with the existing literature, our data indicated an overall global processing bias. However, this overall visual processing style did not vary with participants' number of autism-like traits. These results suggest that the visual processing of Navon figures may be different in typical individuals vs. those with an autism spectrum disorder, with those differences potentially reflecting specific stimulus and task settings.

Reminders of Social Connection Can Attenuate Anthropomorphism.

It is a fundamental human need to secure and sustain a sense of social belonging. Previous research has shown that individuals who are lonely are more likely than people who are not lonely to attribute humanlike traits (e.g., free will) to nonhuman agents (e.g., an alarm clock that makes people get up by moving away from the sleeper), presumably in an attempt to fulfill unmet needs for belongingness. We directly replicated the association between loneliness and anthropomorphism in a larger sample ( N = 178); furthermore, we showed that reminding people of a close, supportive relationship reduces their tendency to anthropomorphize. This finding provides support for the idea that the need for belonging has causal effects on anthropomorphism. Last, we showed that attachment anxiety-characterized by intense desire for and preoccupation with closeness, fear of abandonment, and hypervigilance to social cues-was a stronger predictor of anthropomorphism than loneliness was. This finding helps clarify the mechanisms underlying anthropomorphism and supports the idea that anthropomorphism is a motivated process reflecting the active search for potential sources of connection.