Distributed learning episodes create a context fear memory outside the hippocampus that depends on perirhinal and anterior cingulate cortices

Damage to the hippocampus (HPC) typically causes retrograde amnesia for contextual fear conditioning. Repeating the conditioning over several sessions, however, can eliminate the retrograde amnesic effects. This form of reinstatement thus permits modifications to networks that can support context memory retrieval in the absence of the HPC. The present study aims to identify cortical regions that support the nonHPC context memory. Specifically, the contribution of the perirhinal cortex (PRH) and the anterior cingulate cortex (ACC) were examined because of their established importance to context memory. The findings show that context memories established through distributed reinstatement survive damage limited only to the HPC, PRH, or ACC. Combined lesions of the HPC and PRH, as well as the HPC and ACC, caused retrograde amnesia, suggesting that network modifications in the PRH and ACC enable context fear memories to become resistant to HPC damage.

Intact context memory performance in adults with autism spectrum disorder

Research on memory in autism spectrum disorder (ASD) finds increased difficulty encoding contextual associations in episodic memory and suggests executive dysfunction (e.g., selective attention, cognitive flexibility) and deficient metacognitive monitoring as potential contributing factors. Findings from our lab suggest that age-related impairments in selective attention contribute to those in context memory accuracy and older adults tended to show dependence in context memory accuracy between relevant and irrelevant context details (i.e., hyper-binding). Using an aging framework, we tested the effects of selective attention on context memory in a sample of 23 adults with ASD and 23 typically developed adults. Participants studied grayscale objects flanked by two types of contexts (color, scene) on opposing sides and were told to attend to only one object-context relationship, ignoring the other context. At test, participants made object and context recognition decisions and judgment of confidence decisions allowing for an evaluation of context memory performance, hyper-binding, and metacognitive performance for context judgments in a single task. Results showed that adults with ASD performed similarly to typically developed adults on all measures. These findings suggest that context memory performance is not always disrupted in adults with ASD, even when demands on selective attention are high. We discuss the need for continued research to evaluate episodic memory in a wider variety of adults with ASD.

A selective benefit of transient, but not sustained, reward to memory formation

Reward benefits to memory formation have been robustly linked to dopaminergic activity. Despite established characterization of dopaminergic mechanisms as operating at multiple timescales, potentially supporting distinct functional outcomes, the temporal dynamics by which reward might modulate memory encoding are just beginning to be investigated. In the present study, we leveraged a mixed block/event experimental design to disentangle transient and sustained reward influences on task engagement and subsequent recognition memory in an adapted monetary-incentive encoding (MIE) paradigm. Across three behavioral experiments, transient and sustained reward modulation of item and context memory was probed, at both 24-hour and ~10-minute retention intervals, to investigate the importance of overnight consolidation. In general, we observed that transient reward was associated with enhanced item memory encoding, while sustained reward modulated task engagement at encoding (specifically, increasing response speed) but did not confer a benefit to subsequent memory performance. Notably, reward benefits to item memory performance were somewhat inconsistent across the three experiments, and in contrast to predictions, we did not observe reward modulation of context memory performance or amplification of reward effects by overnight consolidation. Taken together, the observed pattern of behavior suggests potentially distinct roles for transient and sustained reward in memory encoding and cognitive performance and suggests that further investigation of the temporal dynamics of dopaminergic contributions to memory formation will advance understanding of motivated memory.

Exploring the generalisation of affect across related experiences: A study of affective bleed and memory precision

When positive or negative events occur in a context, memory can be reflected in how positively or negatively we judge that context, and also by whether, upon later remembering that emotional event, we can bring to mind the specific context in which it occurred. We examined each of these forms of associative memory, comparing performance when positive, negative, or neutral stimuli were paired with a context. By doing so, we could contribute to debates about how emotion affects associative binding. Participants intentionally formed associations between famous places and positive, negative, or neutral pictures. In Experiment 1, we observed shifts in judgments for places as a function of associated valence; effects summated over accumulated experiences. In Experiment 2, memory precision was examined by manipulating whether lures on a five-alternative forced-choice recognition, included different places or alternate views of the target. Results revealed emotional impairments in associative memory and a selective decrease in precision for negative pairs. Eye-tracking showed more saccades between pictures for remembered pairs, but less of these inter-item saccades when pictures were emotional. Overall findings suggest that positive and negative affect are transferred similarly through episodic associations, although the specificity of context transfer may be lessened for negative content.

Memory for spatio-temporal contextual details during the retrieval of naturalistic episodes

Episodic memory entails the storage of events together with their spatio-temporal context and retrieval comprises the subjective experience of a link between the person who remembers and the episode itself. We used an encoding procedure with mobile-phones to generate experimentally-controlled episodes in the real world: object-images were sent to the participants' phone, with encoding durations up to 3 weeks. In other groups of participants, the same objects were encoded during the exploration of a virtual town (45 min) or using a standard laboratory paradigm, with pairs of object/place-images presented in a sequence of unrelated trials (15 min). At retrieval, we tested subjective memory for the objects (remember/familiar) and memory for the context (place and time). We found that accurate and confident context-memory increased the likelihood of “remember” responses, in all encoding contexts. We also tested the participants' ability to judge the temporal-order of the encoded episodes. Using a model of temporal similarity, we demonstrate scale-invariant properties of order-retrieval, but also highlight the contribution of non-chronological factors. We conclude that the mechanisms governing episodic memory retrieval can operate across a wide range of spatio-temporal contexts and that the multi-dimensional nature of the episodic traces contributes to the subjective experience of retrieval.

STOP SHOUTING AT ME: The Influence of Case and Self-Referencing on Explicit and Implicit Memory

Evidence suggests that physical changes in word appearance, such as those written in all capital letters, and the use of effective encoding strategies, such as self-referential processing, improves memory. In this study we examined the extent both physical changes in word appearance (case) and encoding strategies engaged at study influence memory as measured by both explicit and implicit memory measures. Participants studied words written in upper and lower case under three encoding conditions (self-reference, semantic control, case judgment), which was followed by an implicit (word stem completion) and then an explicit (item and context) memory test. There were two primary results. First, analyses indicated a case enhancement effect for item memory where words written in upper case were better remembered than lower case, but only when participants were prompted to attend to the case of the word. Importantly, this case enhancement effect came at a cost to context memory for words written in upper case. Second, self-referencing increased explicit memory performance relative to control, but there was no effect on implicit memory. Overall, results suggest an item-context memory trade-off for words written in upper case, highlighting a potential downside to writing in all capital letters, and further, that both physical changes to the appearance of words and differing encoding strategies have a strong influence on explicit, but not implicit memory.

Cultural differences in memory for faces and associated perceptual versus social contexts.

The current study investigates cultural differences in memory for faces and their associated contexts between East Asian and Western cultures. Thirty-six Caucasian Canadian (age range = 17 - 30, M = 21.00, SD = 3.94) and 35 native Chinese (age range = 19 – 27, M = 22.06, SD = 2.33) young adults participated in the study. At encoding, participants subjectively rated face stimuli according to the cue words within social (“FRIENDLY” vs. “SUCCESS”) and perceptual (“HEIGHT” vs. “WEIGHT”) contexts. At test, participants performed a context recognition task to identify whether the test stimulus was a new face or an old face associated with a specific context cue word. Results did not show any cultural difference in memory. However, both cultures showed better recognition in the social context than in the perceptual context condition. In addition, the other race effect was observed in context memory for Canadian, but not Chinese participants.

Cultural differences in memory for faces and associated perceptual versus social contexts.

The current study investigates cultural differences in memory for faces and their associated contexts between East Asian and Western cultures. Thirty-six Caucasian Canadian (age range = 17 - 30, M = 21.00, SD = 3.94) and 35 native Chinese (age range = 19 – 27, M = 22.06, SD = 2.33) young adults participated in the study. At encoding, participants subjectively rated face stimuli according to the cue words within social (“FRIENDLY” vs. “SUCCESS”) and perceptual (“HEIGHT” vs. “WEIGHT”) contexts. At test, participants performed a context recognition task to identify whether the test stimulus was a new face or an old face associated with a specific context cue word. Results did not show any cultural difference in memory. However, both cultures showed better recognition in the social context than in the perceptual context condition. In addition, the other race effect was observed in context memory for Canadian, but not Chinese participants.

Aging, Culture, and Memory for Socially Meaningful Item-Context Associations: An East-West Cross-Cultural Comparison Study

Research suggests that people in Eastern interdependent cultures process information more holistically and attend more to contextual information than do people in Western independent cultures. The current study examined the effects of culture and age on memory for socially meaningful item-context associations in 71 Canadians of Western European descent (35 young and 36 older) and 72 native Chinese citizens (36 young and 36 older). All participants completed two blocks of context memory tasks. During encoding, participants rated pictures of familiar objects. In one block, objects were rated either for their meaningfulness in the independent living context or their typicality in daily life. In the other block, objects were rated for their meaningfulness in the context of fostering relationships with others or for their typicality in daily life. The encoding in each block was followed by a recognition test in which participants identified pictures and their associated contexts. The results showed that Chinese outperformed Canadians in context memory, though both culture groups showed similar age-related deficits in item and context memory. The results suggest that Chinese are at an advantage in memory for socially meaningful item-context associations, an advantage that continues from young adulthood into old age.

Aging, Culture, and Memory for Socially Meaningful Item-Context Associations: An East-West Cross-Cultural Comparison Study

Research suggests that people in Eastern interdependent cultures process information more holistically and attend more to contextual information than do people in Western independent cultures. The current study examined the effects of culture and age on memory for socially meaningful item-context associations in 71 Canadians of Western European descent (35 young and 36 older) and 72 native Chinese citizens (36 young and 36 older). All participants completed two blocks of context memory tasks. During encoding, participants rated pictures of familiar objects. In one block, objects were rated either for their meaningfulness in the independent living context or their typicality in daily life. In the other block, objects were rated for their meaningfulness in the context of fostering relationships with others or for their typicality in daily life. The encoding in each block was followed by a recognition test in which participants identified pictures and their associated contexts. The results showed that Chinese outperformed Canadians in context memory, though both culture groups showed similar age-related deficits in item and context memory. The results suggest that Chinese are at an advantage in memory for socially meaningful item-context associations, an advantage that continues from young adulthood into old age.