Shared neural codes of recognition memory.

Recognition memory research has identified several electrophysiological indicators of successful memory retrieval, known as old-new effects. These effects have been observed in different sensory domains using various stimulus types, but little attention has been given to their similarity or distinctiveness and the underlying processes they may share. Here, a data-driven approach was taken to investigate the temporal evolution of shared information content between different memory conditions using openly available EEG data from healthy human participants of both sexes, taken from six experiments. A test dataset involving personally highly familiar and unfamiliar faces was used. The results show that neural signals of recognition memory for face stimuli were highly generalized starting from around 200 ms following stimulus onset. When training was performed on non-face datasets, an early (around 200-300 ms) to late (post-400 ms) differentiation was observed over most regions of interest. Successful cross-classification for non-face stimuli (music and object/scene associations) was most pronounced in late period. Additionally, a striking dissociation was observed between familiar and remembered objects, with shared signals present only in the late window for correctly remembered objects, while cross-classification for familiar objects was successful in the early period as well. These findings suggest that late neural signals of memory retrieval generalize across sensory modalities and stimulus types, and the dissociation between familiar and remembered objects may provide insight into the underlying processes.

A feasibility study of sample re-collection in the analysis of selected volatile compounds in breath samples using GC×GC-TOFMS.

In this study, we aimed to assess the feasibility of re-collecting breath samples using the Centri® (Markes International, Bridgend, UK) followed by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) analysis. The work was conducted in two main phases. In the first phase, we evaluated the re-collection performance by analyzing two sets of standards, including a Grob mix primary solution and a standard mixture of 20 selected volatile compounds (VCs) covering different classes of organic species commonly found in breath samples. The intra-day and inter-day precision (reported as relative standard deviation (RSD),%) for the re-collection of the Grob mix primary solution were in the range of 1 % to14 % and 3 % to12 %, respectively. The re-collection accuracy ranged from 78 % to 97 %. The intra-day RSD for the re-collection of the standard mixture of selected VCs was within 20 % for all compounds, except for acetone and nonane. The precision was within 25 % for all compounds, except for nonane, n-hexane, 1,4-dichlorobenzene, and decane, which exhibited less than 36 % RSD. The re-collection accuracy was in the range of 67 % to 129 %. In the second phase of the study, the re-collection performance in breath analysis was evaluated via five repetitive splitting and re-collection of six breath samples obtained from healthy adults, realizing a total of 30 breath analyses. Initially, we evaluated the re-collection performance by considering all features obtained from breath analysis and then focused on the 20 VCs commonly found in breath samples. The re-collection accuracy for total breath features ranged from 86 to 103 %, and the RSDs were in the range of 1.0 % to 10.4 %. For the selected VCs, the re-collection accuracy of all compounds, except for undecane and benzene, was in the range of 71 % to 132 %.

Affective music during episodic memory recollection modulates subsequent false emotional memory traces: an fMRI study.

Music is a powerful medium that influences our emotions and memories. Neuroscience research has demonstrated music's ability to engage brain regions associated with emotion, reward, motivation, and autobiographical memory. While music's role in modulating emotions has been explored extensively, our study investigates whether music can alter the emotional content of memories. Building on the theory that memories can be updated upon retrieval, we tested whether introducing emotional music during memory recollection might introduce false emotional elements into the original memory trace. We developed a 3-day episodic memory task with separate encoding, recollection, and retrieval phases. Our primary hypothesis was that emotional music played during memory recollection would increase the likelihood of introducing novel emotional components into the original memory. Behavioral findings revealed two key outcomes: 1) participants exposed to music during memory recollection were more likely to incorporate novel emotional components congruent with the paired music valence, and 2) memories retrieved 1 day later exhibited a stronger emotional tone than the original memory, congruent with the valence of the music paired during the previous day's recollection. Furthermore, fMRI results revealed altered neural engagement during story recollection with music, including the amygdala, anterior hippocampus, and inferior parietal lobule. Enhanced connectivity between the amygdala and other brain regions, including the frontal and visual cortex, was observed during recollection with music, potentially contributing to more emotionally charged story reconstructions. These findings illuminate the interplay between music, emotion, and memory, offering insights into the consequences of infusing emotional music into memory recollection processes.

A third kind of episodic memory: Context familiarity is a distinct process from item familiarity and recollection.

Episodic memory is accounted for with two processes: 'familiarity' when generally recognizing an item and 'recollection' when retrieving the full contextual details bound with the item. Paradoxically, people sometimes report contextual information as familiar but without recollecting details, which is not easily accounted for by existing theories. We tested a combination of item recognition confidence and source memory, focusing upon 'item-only hits with source unknown' ('item familiarity'), 'low-confidence hits with correct source memory' ('context familiarity'), and 'high-confidence hits with correct source memory' ('recollection'). Results across multiple within-subjects (trial-wise) and between subjects (individual variability) levels indicated these were behaviorally and physiologically distinct. Behaviorally, a crossover interaction was evident in response times, with context familiarity being slower than each condition during item recognition, but faster during source memory. Electrophysiologically, a Condition x Time x Location triple dissociation was evident in event-related potentials (ERPs), which was then independently replicated. Context familiarity exhibited an independent negative central effect from 800-1200 ms, differentiated from positive ERPs for item-familiarity (400 to 600 ms) and recollection (600 to 900 ms). These three conditions thus reflect mutually exclusive, fundamentally different processes of episodic memory. Context familiarity is a third distinct process of episodic memory.

Neural correlates of retrieval success and precision: an fMRI study.

Prior studies examining the neural mechanisms underlying retrieval success and precision have yielded inconsistent results. Here, their neural correlates were examined using a memory task that assessed precision for spatial location. A sample of healthy young adults underwent fMRI scanning during a single study-test cycle. At study, participants viewed a series of object images, each placed at a randomly selected location on an imaginary circle. At test, studied images were intermixed with new images and presented to the participants. The requirement was to move a cursor to the location of the studied image, guessing if necessary. Participants then signaled whether the presented image as having been studied. Memory precision was quantified as the angle between the studied location and the location selected by the participant. A precision effect was evident in the left angular gyrus, where BOLD activity covaried across trials with location accuracy. Multi-voxel pattern analysis also revealed a significant item-level reinstatement effect for high-precision trials. There was no evidence of a retrieval success effect in the angular gyrus. BOLD activity in the hippocampus was insensitive to both success and precision. These findings are partially consistent with prior evidence that success and precision are dissociable features of memory retrieval.

Eyes on Memory: Pupillometry in Encoding and Retrieval.

This review critically examines the contributions of pupillometry to memory research, primarily focusing on its enhancement of our understanding of memory encoding and retrieval mechanisms mainly investigated with the recognition memory paradigm. The evidence supports a close link between pupil response and memory formation, notably influenced by the type of novelty detected. This proposal reconciles inconsistencies in the literature regarding pupil response patterns that may predict successful memory formation, and highlights important implications for encoding mechanisms. The review also discusses the pupil old/new effect and its significance in the context of recollection and in reflecting brain signals related to familiarity or novelty detection. Additionally, the capacity of pupil response to serve as a true memory signal and to distinguish between true and false memories is evaluated. The evidence provides insights into the nature of false memories and offers a novel understanding of the cognitive mechanisms involved in memory distortions. When integrated with rigorous experimental design, pupillometry can significantly refine theoretical models of memory encoding and retrieval. Furthermore, combining pupillometry with neuroimaging and pharmacological interventions is identified as a promising direction for future research.

How schema knowledge influences memory in older adults: Filling in the gaps, or leading memory astray?

Age-related declines in episodic memory do not affect all types of mnemonic information equally: when to-be-remembered information is in line with one's prior knowledge, or schema-congruent, older adults often show no impairments. There are two major accounts of this effect: One proposes that schemas compensate for memory failures in aging, and the other proposes that schemas instead actively impair older adults' otherwise intact memory for incongruent information. However, the evidence thus far is inconclusive, likely due to methodological constraints in teasing apart these complex underlying dynamics. We developed a paradigm that separately examines the contributions of underlying memory and schema knowledge to a final memory decision, allowing these dynamics to be examined directly. In the present study, healthy older and younger adults first searched for target objects in congruent or incongruent locations within scenes. In a subsequent test, participants indicated where in each scene the target had been located previously, and provided confidence-based recognition memory judgments that indexed underlying memory, in terms of recollection and familiarity, for the background scenes. We found that age-related increases in schema effects on target location spatial recall were predicted and statistically mediated by age-related increases in underlying memory failures, specifically within recollection. We also found that, relative to younger adults, older adults had poorer spatial memory precision within recollected scenes but slightly better precision within familiar scenes-and age increases in schema bias were primarily exhibited within recollected scenes. Interestingly, however, there were also slight age-related increases in schema effects that could not be explained by memory deficits alone, outlining a role for active schema influences as well. Together, these findings support the account that age-related schema effects on memory are compensatory in that they are driven primarily by underlying memory failures, and further suggest that age-related deficits in memory precision may also drive schema effects.

The effect of target detection task on memory encoding varies in different stimulus onset asynchronies.

The attentional boost effect (ABE) and action-induced memory enhancement (AIME) suggest that memory performance for target-paired items is superior to that for distractor-paired items when participants performed a target detection task and a memory encoding task simultaneously. Though the memory enhancement has been well established, the temporal dynamics of how the target detection task influenced memory encoding remains unclear. To investigate this, we manipulated the stimulus onset asynchrony (SOA) between detection stimuli and the words to be memorized using a remember/know study-test paradigm, and we focused primarily on memory performance for the words that appeared after the detection response. The results showed that target-paired memory enhancement was robust from SOA = 0 s to SOA = 0.75 s, but was not significant when examined by itself in Experiment 1A or weakened in Experiment 2 and the conjoint analysis when SOA = 1 s, which were only observed in R responses. The post-response memory enhancement still existed when there was no temporal overlap between the word and target, similar to the magnitude of memory enhancement observed with temporal overlap. These results supported the view that target-paired memory enhancement (recollection rather than familiarity) occurred irrespective of whether the items appeared simultaneously with the targets or within a short period after the response, and the temporal overlap of the word and target was not necessary for post-response memory enhancement.

Recognizing ideas generated in a creative task: the roles of the hippocampus and medial prefrontal cortex in facilitating self-generated learning.

Creative idea generation plays an important role in promoting successful memory formation. Yet, its underlying neural correlates remain unclear. We investigated the self-generated learning of creative ideas motivated by the schema-linked interactions between medial prefrontal and medial temporal regions framework. This was achieved by having participants generate ideas in the alternative uses task, self-evaluating their ideas based on novelty and source (i.e. new or old), and then later being tested on the recognition performance of the generated ideas. At the behavioral level, our results indicated superior performances in discriminating novel ideas, highlighting the novelty effect on memory. At the neural level, the regions-of-interest analyses revealed that successful recognition of novel ideas was associated with greater activations in the hippocampus (HPC) and medial prefrontal cortex (mPFC) during ideation. However, only activation in the right HPC was positively related to the successful recognition of novel ideas. Importantly, the weaker the connection between the right HPC and left mPFC, the higher the recognition accuracy of novel ideas. Moreover, activations in the right HPC and left mPFC were both effective predictors of successful recognition of novel ideas. These findings uniquely highlight the role of novelty in promoting self-generated learning of creative ideas.

Time and memory distrust shape the dynamics of recollection and belief-in-occurrence.

The current study examined how people's metamemory judgments of recollection and belief-in-occurrence change over time. Furthermore, we examined to what extent these judgments are affected by memory distrust - the subjective appraisal of one's memory functioning - as measured by the Memory Distrust Scale (MDS) and the Squire Subjective Memory Scale (SSMQ). Participants (N = 234) studied pictorial stimuli and were tested on some of these stimuli later in the same session, but were tested on other stimuli 1, 2, 4, 8, and 17 days later. Recollection and belief ratings were correlated highly and followed similar declining patterns over time. However, belief decreased relatively more slowly than recollection, such that the discrepancy between recollection and belief increased over time. Memory distrust moderated the association between recollection and belief, with this association being weaker among people who reported greater (versus lower) memory distrust. Memory distrust also interacted with retention period to predict memory judgments. Two measures of memory distrust diverged in their predictive power. In particular, only the MDS predicted the spontaneous reporting of nonbelieved memories. Our results provide support to the theoretical perspective that belief-in-occurrence is a summative judgment informed not only by recollective phenomenology but also by metamemorial beliefs.

The effect of value on context and target recollection in memory for truth and falsity.

Memory for truth and falsity has recently been investigated from the perspective of the dual-recollection theory, showing better context and target recollection for truth than falsity. In this paper, we examine whether these memory effects obtained for true statements are similar to the value effect, whereby true statements are given higher priority in encoding. For this purpose, we implemented value-directed remembering (VDR) into the conjoint-recognition paradigm. In our first experiment, the primary goal was to verify how VDR influences the processes defined by dual-recollection theory. At study, prioritized/important items were linked to higher numerical values (e.g., 10), while unimportant ones had lower values (e.g., 1). At test, the participants' task was to recognize whether a particular sentence was important, unimportant, or new. We found that both context and target recollection were better for important items. In the second experiment, the main goal was to study the combined effects of importance and veracity on memory. In the between-subjects design, participants were monetarily rewarded for memorizing true or false sentences. The results demonstrated differences in the ability to prioritize truth over falsity. Specifically, we found a substantial increase in context recollection for prioritized true information but not for prioritized false information. Moreover, we found higher context recollection for true than false sentences in the true-prioritized condition, but not in the false-prioritized condition. These results indicated that people are able to prioritize true information better than false, and suggested that memory for truth may be a special case of the value effect.

Working memory training improves episodic memory in older people: transfer based on controlled retrieval processes.

Introduction: The results of working memory (WM) training to improve episodic memory in older people are inconsistent. This inconsistency could be due to the fact that the episodic memory tests used do not share the same cognitive resources as the trained WM task. The aim of this study was to assess whether performance on an episodic memory test will improve only when this test requires controlled processes of retrieval of information from secondary memory or recollection, similar to the processes exercised during WM training. Method: Fifty-five people over 60 years of age participated in the study: 27 were randomly assigned to the experimental group (EG) and the rest to the control group (CG). The EG was trained in complex span tasks. Before and after training, both groups were tested on episodic memory tests (a verbal and a visuospatial recognition test) and WM span tasks (reading, digit and spatial location). Results: ANOVAs revealed a greater improvement of recollection estimates in the EG than in the CG for both verbal recognition (p = 0.023) and visuospatial recognition (p = 0.014). Discussion: Our results provide support for a cognitive mechanism whose shared presence favored transfer from training on a WM task to a test of episodic memory. Consistent with our predictions, training on complex span tasks improved performance on recognition tests only when recall required a controlled search process in secondary memory, or recollection. We therefore stress the importance of identifying other cognitive resources that are susceptible to transfer from a training task to other untrained tasks. A better understanding of the phenomenon of transfer is crucial for the design of increasingly effective intervention programs for older people.

Examining the effects of pleasantness ratings on correct and false recognition in the DRM paradigm: accuracy, recollection and familiarity estimates.

Distinctive encoding usually increases correct recognition while also producing a reduction in false recognition. In the Deese-Roediger-McDermott (DRM) illusion this phenomenon, called the mirror effect, occurs when participants focus on unique features of each of the words in the study list. In previous studies, the pleasantness rating task, used to foster distinctive encoding, generated different patterns of results. The main aim of our research is to examine under what circumstances this task can produce the mirror effect in the DRM paradigm, based on evidence from recognition accuracy and subjective retrieval experience. In Experiment 1, a standard version (word pleasantness rating on a 5-point Likert-type scale) was used for comparison with two other encoding conditions: shallow processing (vowel identification) and a read-only control. The standard task, compared to the other conditions, increased correct recognition, but did not reduce false recognition, and this result may be affected by the number of lists presented for study. Therefore, in experiment 2, to minimize the possible effect of the so-called retention size, the number of studied lists was reduced. In addition, the standard version was compared with a supposedly more item-specific version (participants rated the pleasantness of words while thinking of a single reason for this), also including the read-only control condition. In both versions of the pleasantness rating task, more correct recognition is achieved compared to the control condition, with no differences between the two versions. In the false recognition observed here, only the specific pleasantness rating task achieved a reduction relative to the control condition. On the other hand, the subjective retrieval experience accompanied correct and false recognition in the various study conditions. Although the standard pleasantness rating task has been considered to perform item-specific processing, our results challenge that claim. Furthermore, we propose a possible boundary condition of the standard task for the reduction of false recognition in the DRM paradigm.

Redundancy effect of initial enactment encoding and subsequent testing on memory enhancement: Insights from an electrophysiological study.

Testing is more beneficial for memory retention than restudying the same content. However, the effect of the initial encoding method on the testing effect remains unclear. In this study, a classical testing effect paradigm was employed, along with event-related potentials (ERP), to investigate the electrophysiological processes underlying the effect of enactment encoding on the testing effect. Participants were randomly assigned to the Self-Performed Test (SPT) or Verbalized Test (VT) groups. Both groups underwent three stages: an initial encoding phase, an initial test phase (comprising a source memory task and a restudy task), and a final test phase. During the initial encoding phase, the SPT group encoded action phrases through enactment, while the VT group encoded information through reading. During the initial test phase, the SPT group exhibited superior recognition performance in item memory compared with the VT group. Both groups exhibited significant parietal old/new effects in the source memory task, with only the SPT group displaying parietal positivity during the restudy task. During the final test phase, the behavioral testing effect was exclusively observed in the VT group. Furthermore, the VT group displayed a more pronounced parietal positivity in the test condition compared to the restudy condition, while the parietal positivity between the two conditions was comparable in the SPT group. In summary, the absence of a final behavioral testing effect in the SPT group may be attributed to both enactment and testing primarily enhancing memory performance through recollection-based retrieval, as indicated by the parietal positivity. Consequently, the initial enactment encoding method leaves limited scope for further improvements through subsequent testing. These findings suggest that initial enactment encoding, and subsequent testing may be redundant in improving episodic memory performance.

Comparing two unitisation manipulations: effects on familiarity, recollection-based recognition, and semantic interference.

The recognition of associative memory can be significantly influenced by the use of an encoding strategy known as unitisation, which has been implemented through various manipulations. However, [Shao, H., Opitz, B., Yang, J., & Weng, X. (2016). Recollection reduces unitised familiarity effect. Memory (Hove, England), 24(4), 535-547. https://doi.org/10.1080/09658211.2015.1021258] found intriguing distinctions between two common manipulations, the compound task and the imagery task, leading to a dispute. We propose that differences in levels of processing in the imagery task may account for these discrepancies. This study tested our hypothesis using two approaches. The first two experiments utilised the R/K paradigm to investigate the effects of these methods on familiarity-based and recollection-based recognition. The results demonstrated that familiarity was increased in the compound task, while recollection was increased in the imagery task. In the subsequent two experiments, an interference paradigm was employed to examine differences in semantic processing within the two tasks. The results showed that the compound task did not impact participants' inclination towards lures, while the imagery task led to a bias towards semantic lures over episodic lures, suggesting that the two encodings in the imagery task involve different levels of semantic processing. These results support our hypothesis and underscore the importance of carefully choosing comparisons that account for other variables in the study of unitisation.

The effect of part-list cuing on associative recognition.

The modulation of part-list cuing on item memory has been well-documented, whereas its impact on associative memory remains largely unknown. The present study explored the effect of part-list cuing on associative recognition and, more specifically, whether this forgetting effect caused by part-list cuing is more sensitive to recollection or familiarity in recognition memory. Experiments 1a and 1b combined the intact/rearranged/new judgement task of associative recognition with the classical part-list cuing paradigm, and the result showed that part-list cuing impaired the recognition accuracy of "intact" and "rearranged" face-scene pairs. Moreover, the discriminability score of relational recognition and item recognition was significantly decreased in the part-list cuing condition compared to the no-part-list cuing condition. Experiments 2a and 2b further used the Remember/Know/Guess task to explore which recognition processes (recollection vs. familiarity) were sensitive to the presentation of part-list cuing. The results showed that part-list cuing reduced the familiarity of relational recognition and the recollection and familiarity of item recognition. These findings suggest that part-list cuing was harmful to the recognition of relationships (familiarity) and items (recollection and familiarity) in associative memory.

Tuned geometries of hippocampal representations meet the computational demands of social memory.

Social memory consists of two processes: the detection of familiar compared with novel conspecifics and the detailed recollection of past social episodes. We investigated the neural bases for these processes using calcium imaging of dorsal CA2 hippocampal pyramidal neurons, known to be important for social memory, during social/spatial encounters with novel conspecifics and familiar littermates. Whereas novel individuals were represented in a low-dimensional geometry that allows for generalization of social identity across different spatial locations and of location across different identities, littermates were represented in a higher-dimensional geometry that supports high-capacity memory storage. Moreover, familiarity was represented in an abstract format, independent of individual identity. The degree to which familiarity increased the dimensionality of CA2 representations for individual mice predicted their performance in a social novelty recognition memory test. Thus, by tuning the geometry of structured neural activity, CA2 is able to meet the demands of distinct social memory processes.

Effects of congruent emotional contexts during encoding on recognition: An ERPs study.

Past research showed that emotional contexts can impair recognition memory for the target item. Given that item-context congruity may enhance recognition memory, the present study aims to examine the effect of the congruent emotional encoding contexts on recognition memory. Participants studied congruent word-picture pairs (e.g., the word "cow" - a picture describing a cow) and incongruent word-picture pairs (e.g., the word "cow" - a picture describing a goat) and, subsequently, were asked to report the nature of the picture (emotional or neutral). Behavioral results revealed that emotional contexts impaired source but not item recognition, with congruent word-context mitigating this impairment and enhancing item recognition. Neural results from ERPs and theta oscillations found the recollection process, as shown by the LPC old/new effect and theta oscillations, for both item and source recognition across emotional contexts, irrespective of congruity. Meanwhile, the familiarity process as indexed by the FN400 old/new effect was found only for item recognition in congruent emotional contexts. These findings suggest that the congruent relationship of item-context could mitigate the emotion-induced source memory impairment and enhance item memory, with neural results elucidating the memory processes involved in retrieval of emotional information. Specifically, while emotion-related information generally elicits the recollection-based memory process, only congruent emotional information elicits the familiarity-based process.

The effects of age on objective and subjective recollection after visiting a virtual apartment.

While aging has been associated with decreased retrieval of episodic memory details, subjective ratings about memory quality seem to remain stable. This suggests that subjective memory judgments are based on different information according to age. Here, we tested the hypothesis that older people would rather base their subjective judgments on the retrieval of personal elements (such as emotions and thoughts), whereas younger people would rather base their judgments on the retrieval of event-related elements (such as time, place, and perceptual details). Sixty participants (20 to 79 years old) performed eight actions in a virtual apartment and were then asked to verbally recall each action with a maximum of associated elements and to rate the subjective quality of their memories. The elements reported were classified into "person-related" and "event-related" categories. Executive functions, memory performance on traditional memory tasks, and subjects' perception of memory functioning were also evaluated. Results revealed that aging was associated with reduced retrieval of event-related elements, which was explained by decreasing executive resources. However, age did not affect the retrieval of person-related elements, and the subjective memory judgments of older people were not based on these elements to a greater extent than those of younger people. Finally, our results highlight the value of virtual reality (VR) in memory evaluations since subjects' perception of memory functioning was associated with their performance in the VR task but not in traditional memory tasks.

Does context recollection depend on the base-rate of contextual features?

Episodic recollection is defined by the re-experiencing of contextual and target details of a past event. The base-rate dependency hypothesis assumes that the retrieval of one contextual feature from an integrated episodic trace cues the retrieval of another associated feature, and that the more often a particular configuration of features occurs, the more effective this mutual cueing will be. Alternatively, the conditional probability of one feature given another feature may be neglected in memory for contextual features since they are not directly bound to one another. Three conjoint recognition experiments investigated whether memory for context is sensitive to the base-rates of features. Participants studied frequent versus infrequent configurations of features and, during the test, they were asked to recognise one of these features with (vs. without) another feature reinstated. The results showed that the context recollection parameter, representing the re-experience of contextual features in the dual-recollection model, was higher for frequent than infrequent feature configurations only when the binding of feature information was made easier and the differences in the base-rates were extreme, otherwise no difference was found. Similarly, base-rates of features influenced response guessing only in the condition with salient differences in base-rates. The Bayes factor analyses showed that the evidence from two of our experiments favoured the base-rate neglect hypothesis over the base-rate dependency hypothesis; the opposite result was obtained in the third experiment, but only when high base-rate disproportion and facilitated feature binding conditions were used.