Min Retention Interval Research Articles

Memory Consolidation during Ultra-short Offline States.

Traditionally, neuroscience and psychology have studied the human brain during periods of "online" attention to the environment, while participants actively engage in processing sensory stimuli. However, emerging evidence shows that the waking brain also intermittently enters an "offline" state, during which sensory processing is inhibited and our attention shifts inward. In fact, humans may spend up to half of their waking hours offline [Wamsley, E. J., & Summer, T. Spontaneous entry into an "offline" state during wakefulness: A mechanism of memory consolidation? Journal of Cognitive Neuroscience, 32, 1714-1734, 2020; Killingsworth, M. A., & Gilbert, D. T. A wandering mind is an unhappy mind. Science, 330, 932, 2010]. The function of alternating between online and offline forms of wakefulness remains unknown. We hypothesized that rapidly switching between online and offline states enables the brain to alternate between the competing demands of encoding new information and consolidating already-encoded information. A total of 46 participants (34 female) trained on a memory task just before a 30-min retention interval, during which they completed a simple attention task while undergoing simultaneous high-density EEG and pupillometry recording. We used a data-driven method to parse this retention interval into a sequence of discrete online and offline states, with a 5-sec temporal resolution. We found evidence for three distinct states, one of which was an offline state with features well-suited to support memory consolidation, including increased EEG slow oscillation power, reduced attention to the external environment, and increased pupil diameter (a proxy for increased norepinephrine). Participants who spent more time in this offline state following encoding showed improved memory at delayed test. These observations are consistent with the hypothesis that even brief, seconds-long entry into an offline state may support the early stages of memory consolidation.

Spontaneity matters! Network alterations before and after spontaneous and active facial self-touches: An EEG functional connectivity study

BackgroundDespite humans frequently performing spontaneous facial self-touches (sFST), the function of this behavior remains speculative. sFST have been discussed in the context of self-regulation, emotional homeostasis, working memory processes, and attention focus. First evidence indicates that sFST and active facial self-touches (aFST) are neurobiologically different phenomena. The aim of the present analysis was to examine EEG-based connectivity in the course of sFST and aFST to test the hypotheses that sFST affect brain network interactions relevant for other than sensorimotor processes. MethodsTo trigger spontaneous FST a previously successful setting was used: 60 healthy participants manually explored two haptic stimuli and held the shapes of the stimuli in memory for a 14 min retention interval. Afterwards the shapes were drawn on a sheet of paper. During the retention interval, artifact-free EEG-data of 97 sFST by 32 participants were recorded. At the end of the experiment, the participants performed aFST with both hands successively. For the EEG-data, connectivity was computed and compared between the phases before and after sFST and aFST and between the respective before-and the after-phases. ResultsFor the before-after comparison, brainwide distributed significant connectivity differences (p < .00079) were observed for sFST, but not for aFST. Additionally, comparing the before- and after-phases of sFST and aFST, respectively, revealed increased similarity between the after-phases than between the before-phases. ConclusionThe results support the assumption that sFST and aFST are neurobiologically different phenomena. Furthermore, the aligned network properties of the after-phases compared to the before-phases indicate that sFST serve self-regulatory functions that aFST do not serve.

Retrieval practice plus feedback benefits a third language vocabulary learning

ABSTRACT Three experiments explored how retrieval practice and corrective feedback affect a third language (L3) vocabulary learning. In the first two experiments, Chinese–English bilinguals without prior French language experience studied English (Second Language, L2)–French (L3) word pairs in repeated studying or retrieval practice without (Experiment 1)/with (Experiment 2) corrective feedback. A final recognition test was administered after a 30-min retention interval. Experiment 3 was identical to Experiment 2 in all respects, except that Chinese (First Language, L1)–French (L3) word pairs were used as study materials. Experiment 1 found that repeated studying led to greater accuracy and faster response time on the final test than retrieval practice without feedback. However, the opposite results were found in Experiment 2: retrieval practice with feedback yielded superior performance compared with repeated studying. The benefit of retrieval practice plus feedback was also found in Experiment 3, while it produced larger gains than Experiment 2. These results demonstrate that retrieval practice plus feedback is a powerful learning strategy, and L1–L3 learning is more effective than L2–L3 learning for L3 vocabulary learning. Our findings support the bifurcation model of the retrieval practice effect.

Retrieval practice enhances learning and memory retention of French words in Chinese-English bilinguals

Numerous previous studies have indicated that retrieval practice promotes foreign language learning more than repeated studying. However, few studies have investigated whether retrieval practice enhanced a third language (L3) learning and memory retention. Here, we compared the behavioral performance in retrieval practice with that in repeated studying in French (L3) words learning. Sixty-two Chinese-English bilinguals participated in the experiment consisting of three sessions. Session one began with an initial encoding phase with 120 French (L3) – English (L2) translation word pairs, followed by a short distractor task. In session two, the 120 French-English word pairs from session one were studied under retrieval practice condition or repeated studying condition. The final recognition memory test was conducted after a 30-min retention interval. We found that retrieval practice enhanced French words learning more than repeated studying, as reflected by higher recognition accuracy in retrieval practice condition. The results suggest that retrieval practice is a powerful mnemonic enhancer in promoting L3 vocabulary learning, and it is an effective strategy in learning a new language. However, students rarely realize the important role of retrieval practice in foreign language learning.

Prefrontal Transcranial Direct Current Stimulation Globally Improves Learning but Does Not Selectively Potentiate the Benefits of Targeted Memory Reactivation on Awake Memory Consolidation

Targeted memory reactivation (TMR) and transcranial direct current stimulation (tDCS) can enhance memory consolidation. It is currently unknown whether TMR reinforced by simultaneous tDCS has superior efficacy. In this study, we investigated the complementary effect of TMR and bilateral tDCS on the consolidation of emotionally neutral and negative declarative memories. Participants learned neutral and negative word pairs. Each word pair was presented with an emotionally compatible sound. Following learning, participants spent a 20 min retention interval awake under four possible conditions: (1) TMR alone (i.e., replay of 50% of the associated sounds), (2) TMR combined with anodal stimulation of the left DLPFC, (3) TMR combined with anodal stimulation of the right DLPFC and (4) TMR with sham tDCS. Results evidenced selective memory enhancement for the replayed stimuli in the TMR-only and TMR-sham conditions, which confirms a specific effect of TMR on memory. However, memory was enhanced at higher levels for all learned items (irrespective of TMR) in the TMR-anodal right and TMR-anodal left tDCS conditions, suggesting that the beneficial effects of tDCS overshadow the specific effects of TMR. Emotionally negative memories were not modulated by tDCS hemispheric polarity. We conclude that electrical stimulation of the DLPFC during the post-learning period globally benefits memory consolidation but does not potentiate the specific benefits of TMR.

An Incidental Learning Method to Improve Face-Name Memory in Older Adults With Amnestic Mild Cognitive Impairment.

Forgetting names is a common memory concern for people with amnestic mild cognitive impairment (aMCI) and is related to explicit memory deficits and pathological changes in the medial temporal lobes at the early stages of Alzheimer's disease (AD). In the current experiment, we tested a unique method to improve memory for face-name associations in people with aMCI involving incidental rehearsal of face-name pairs. Older adults with aMCI and age- and education-matched controls learned 24 face-name pairs and were tested via immediate cued recall with faces as cues for associated names. During a 25- to 30-min retention interval, 10 of the face-name pairs reappeared as a quarter of the items on a seemingly unrelated 1-back task on faces, with the superimposed names irrelevant to the task. After the delay, surprise delayed cued recall and forced-choice associative recognition tests were administered for the face-name pairs. Both groups showed reduced forgetting of the names that repeated as distraction and enhanced recollection of these pairs. The results demonstrate that passive methods to prompt automatic retrieval of associations may hold promise as interventions for people with early signs of AD.

Video context-dependent effects in recognition memory

Abstract The present study investigated how video-dependent recognition is influenced by context load (number of items presented per context), the sequence of context presentation (successive or shuffled presentation of short video contexts), and item cue strength (length of study time). In addition, the effects of background photographs selected from still images of the video contexts were also investigated. The present study includes 7 experiments, in which a total of 287 undergraduates intentionally studied a list of unrelated words. After a filled 5-min retention interval, participants received a recognition test. In the same-context condition, the same video as at study was presented at test, whereas in the different-context condition, new videos were presented at test. With a context load of 1 item, a concordant effect and context dependent-recognition discrimination were found in two video experiments and one background-photograph experiment. Successive presentation of 4-s video contexts produced context-dependent effects in hit rate and in d' with a context load of 6 items and study time of 4 seconds per item, and with a context load of 18 items and study time of 1.33 (4/3) seconds per item. In contrast, no effect was found in the false alarm rate in either condition. Nonetheless, when the context load was 18 and the study time was 4 s per item, no effect was found for the hit rate, false alarm rate, or d'. Shuffled presentation of 4-s video contexts produced a concordant effect but no effect for d' with a context load 6 or 18. Between-participants manipulation produced a context-based mirror effect. The present results imply that video context functions mainly as a global environmental context, and sometimes as a local environmental context.

Effects of supplemental creatine and guanidinoacetic acid on spatial memory and the brain of weaned Yucatan miniature pigs.

The emergence of creatine as a potential cognitive enhancement supplement for humans prompted an investigation as to whether supplemental creatine could enhance spatial memory in young swine. We assessed memory performance and brain concentrations of creatine and its precursor guanidinoacetic acid (GAA) in 14-16-week-old male Yucatan miniature pigs supplemented for 2 weeks with either 200 mg/kg∙d creatine (+Cr; n = 7) or equimolar GAA (157 mg/kg∙d) (+GAA; n = 8) compared to controls (n = 14). Spatial memory tests had pigs explore distinct sets of objects for 5 min. Objects were spatially controlled, and we assessed exploration times of previously viewed objects relative to novel objects in familiar or novel locations. There was no effect of either supplementation on memory performance, but pigs successfully identified novel objects after 10 (p < 0.01) and 20 min (p < 0.01) retention intervals. Moreover, pigs recognized spatial transfers after 65 min (p < 0.05). Regression analyses identified associations between the ability to identify novel objects in memory tests and concentrations of creatine and GAA in cerebellum, and GAA in prefrontal cortex (p < 0.05). The concentration of creatine in brain regions was not influenced by creatine supplementation, but GAA supplementation increased GAA concentration in cerebellum (p < 0.05), and the prefrontal cortex of +GAA pigs had more creatine/g and less GAA/g compared to +Cr pigs (p < 0.05). Creatine kinase activity and maximal reaction velocity were also higher with GAA supplementation in prefrontal cortex (p < 0.05). In conclusion, there appears to be a relationship between memory performance and guanidino compounds in the cerebellum and prefrontal cortex, but the effects were unrelated to dietary supplementation. The cerebellum is identified as a target site for GAA accretion.

Age-related differences in appetitive trace conditioning and novel object recognition procedures.

Appetitive trace conditioning (TC) was examined over 6 months in younger-adult (2-8 months) and middle-aged (12-18 months) male Wistar RccHan rats, to test for early age-related impairment in working memory. Novel object recognition (NOR) was included as a comparison task, to provide a positive control in the event that the expected impairment in TC was not demonstrated. The results showed that TC improved at both ages at the 2 s but not at the 10 s trace interval. There was, however, evidence for reduced improvement from one day to the next in the middle-aged cohort tested with the 2 s trace conditioned stimulus. Moreover, within the 10 s trace, responding progressively distributed later in the trace interval, in the younger-adult but not the middle-aged cohort. Middle-aged rats showed NOR discriminative impairment at a 24 h but not at a 10 min retention interval. Object exploration was overall reduced in middle-aged rats and further reduced longitudinally. At the end of the study, assessing neurochemistry by HPLC-ED showed reduced 5-HIAA/5-HT in the dorsal striatum of the middle-aged rats and some correlations between striatal 5-HIAA/5-HT and activity parameters. Overall the results suggest that, taken in isolation, age-related impairments may be overcome by experience. This recovery in performance was seen despite the drop in activity levels in older animals, which might be expected to contribute to cognitive decline.

A brief period of eyes-closed rest enhances motor skill consolidation.

Post-training sleep benefits both declarative and procedural memory consolidation. However, recent research suggests that eyes-closed waking rest may provide a similar benefit. Brokaw et al. (2016), for example, recently demonstrated that verbal declarative memory improved more following a 15 min period of waking rest, in comparison to 15 min of active wake. Here, we used the same procedures to test whether procedural memory similarly benefits from waking rest. Participants were trained on the Motor Sequence Task (MST), followed by a 15 min retention interval during which they either rested with their eyes closed or completed a distractor task. Rest significantly enhanced MST performance, mirroring the effect observed in Brokaw et al. (2016) and demonstrating that waking rest benefits the early stages of procedural memory. An additional group of participants tested 4 h later displayed no effect of rest. Overall, these results suggest that the early MST performance "boost" described in prior studies may depend on post-learning state.

Testing potentiates new learning across a retention interval and a lag: A strategy change perspective

Abstract Practicing retrieval on previously studied materials can potentiate subsequent learning of new materials. In four experiments, we investigated the influence of retention interval and lag on this test-potentiated new learning (TPNL) effect. Participants studied four word lists and either practiced retrieval, restudied, or completed math problems following Lists 1–3. Memory performance on List 4 provided an estimate of new learning. In Experiments 1 and 2, participants were tested on List 4 after either a 1 min or 25 min retention interval. In Experiments 3 and 4, participants took at 25 min break before studying List 4. A TPNL effect was observed in all experiments. To gain insight into the mechanism that may underlie TPNL, we analyzed the extent to which participants organized their recall from list to list. Relative to restudy and math, testing led to superior semantic organization across lists. Our results support a strategy change account of TPNL.

Influences of context load and sensibleness of background photographs on local environmental context-dependent recognition

Abstract The present study explored which theory can best explain local environmental context-dependent recognition. One type of theory (encoding specificity principle) posits that recognition reflects remembering of the past episode, whereas the other theory (ICE: Item Context Ensemble) posits that recognition reflects familiarity-based judgements. In three experiments, a total of 120 undergraduates intentionally studied a list of unrelated words superimposed on background photographs. Half of the photographs contained a specific area where words are typically presented (sensible photographs), and the other half contained no such area (insensible photographs). Context loads were 24, 20, and 4 for Experiments 1, 2, and 3, respectively. After a filled 5-min retention interval, participants received a recognition test. The old words and the same number of new words were randomly presented at test one at a time, and participants were required to respond whether each word was old or new. In the same-context condition, words were presented at test on the same photograph as at study, whereas in the different-context condition, a new background photograph was presented at test. Context-dependent recognition discrimination was found only with the sensible photographs but not with insensible ones in Experiments 1 and 2, whereas both sensible and insensible photographs showed significant context-dependent recognition discrimination in Experiment 3. Experiments 1 and 2 showed the concordant effects, but no effect in the false alarm rate was found in Experiment 3. The present results imply that there are remembering- based and familiarity-based production mechanisms for local environmental context-dependent recognition. The context load may mediate the shift from one to the other.

Leveraging older adults' susceptibility to distraction to improve memory for face-name associations.

Forgetting people's names is a common memory complaint among older adults and one that is consistent with experimental evidence of age-related decline in memory for face-name associations. Despite this difficulty intentionally forming face-name associations, a recent study demonstrated that older adults hyperbind distracting names and attended faces, which produces better learning of these face-name pairs when they reappear on a memory test (Weeks, Biss, Murphy, & Hasher, 2016). The current study explored whether this effect could be leveraged as an intervention to reduce older adults' forgetting of face-name associations, using a method previously shown to improve older adults' retention of a word list (Biss, Ngo, Hasher, Campbell, & Rowe, 2013). Twenty-five younger and 32 older adults studied 24 face-name pairs and were tested via immediate and delayed memory tests. During the 30-min retention interval, 10 of the face-name pairs reoccurred as distraction in an ostensibly unrelated face-judgment task, providing an opportunity to implicitly rehearse these pairs. Older adults showed reduced forgetting of repeated face-name pairs as well as improved recollection. Younger adults showed no reliable benefit. These findings indicate that useful distraction benefits older adults' memory for face-name associations, suggesting its potential utility as a memory intervention technique. (PsycINFO Database Record

The roles of remembering and outshining in global environmental context-dependent recognition

Abstract The present study investigated whether odor and background-music dependent recognition is best explained by the outshining account, consisting of the encoding-specificity and the outshining principles. In contrast, the ICE theory posits that recognition of a past episode involves judgment processes based on global activation of the item, the context, and the ensemble information in the probe and memory. Experiments 1 and 2 manipulated odor contexts, and Experiment 3 manipulated background-music context. In the three experiments, a total of 384 undergraduates intentionally studied a list of unrelated words. After a filled 5-min retention interval, participants received a recognition test on paper. In the same-context (SC) condition, the same odor or musical piece was presented during both study and test, whereas in the different-context (DC) condition, different odors or musical pieces were presented at study and test. Context-dependent recognition discrimination was found when the hit rate in the DC condition was low but not when it was high. Furthermore, context-dependent recognition discrimination was found when there was a positive context-dependent effect for the hit rate and a negative effect for the false alarm rate, which is a context-based mirror effect. Failure to find context-dependent recognition discrimination occurred when there was no effect for either the hit rate or the false alarm rate. The least-squares regression lines relating the effect sizes of d′ for the DC hit rate, for the odor and background-music contexts, along with previous data of place context, showed that the effect sizes were inversely proportional to the DC hit rate. The present results are best explained by the outshining account, but not by the ICE theory.

Object movement re-enactment in free-ranging Kune Kune piglets

Learning by observing others is especially beneficial for young and naive individuals. The relationship to the social partner is thus important. While peers are often used as demonstrators to test for social learning abilities in a species, thereby studying horizontal transmission of information, this study focused on the vertical transmission of information, i.e. learning across generations, in a highly social species. Half-a-year-old piglets of the Kune Kune breed, Sus scrofa domesticus (in contrast to the usual subjects in studies on pigs raised and kept in seminatural conditions), were first exposed to their mother or aunt pushing one of two differently coloured bars to either the left or right side to open a sliding door, and were then tested after 1 min, 1 h and 1-day retention intervals. Results indicated that subjects recalled the movement of the door, rather than using local or stimulus enhancement. A second test series revealed that the pigs used the demonstrated opening technique and even remembered it after a delay of 24 h. Nonexposed piglets did not show a side bias during their first encounters with the apparatus; however, habit formation was at play during later test sessions and was possibly the reason for long-term memory of the self-acquired techniques. Altogether, this study revealed that piglets learned how to solve a manipulative foraging problem from both their mother and their aunt, probably by acquiring some information through observation and then memorizing it for up to a day.

Lack of spacing effects during piano learning.

Spacing effects during retention of verbal information are easily obtained, and the effect size is large. Relatively little evidence exists on whether motor skill retention benefits from distributed practice, with even less evidence on complex motor skills. We taught a 17-note musical sequence on a piano to individuals without prior formal training. There were five lags between learning episodes: 0-, 1-, 5-, 10-, and 15-min. After a 5-min retention interval, participants’ performance was measured using three criteria: accuracy of note playing, consistency in pressure applied to the keys, and consistency in timing. No spacing effect was found, suggesting that the effect may not always be demonstrable for complex motor skills or non-verbal abilities (timing and motor skills). Additionally, we taught short phrases from five songs, using the same set of lags and retention interval, and did not find any spacing effect for accuracy of song reproduction. Our findings indicate that although the spacing effect is one of the most robust phenomena in the memory literature (as demonstrated by verbal learning studies), the effect may vary when considered in the novel realm of complex motor skills such as piano performance.

Rats Remember Items in Context Using Episodic Memory

Vivid episodic memories in people have been characterized as the replay of unique events in sequential order [1-3]. Animal models of episodic memory have successfully documented episodic memory of a single event (e.g., [4-8]). However, a fundamental feature of episodic memory in people is that it involves multiple events, and notably, episodic memory impairments in human diseases are not limited to a single event. Critically, it is not known whether animals remember many unique events using episodic memory. Here, we show that rats remember many unique events and the contexts in which the events occurred using episodic memory. We used an olfactory memory assessment in which new (but not old) odors were rewarded using 32 items. Rats were presented with 16 odors in one context and the same odors in a second context. To attain high accuracy, the rats needed to remember item in context because each odor was rewarded as a new item in each context. The demands on item-in-context memory were varied by assessing memory with 2, 3, 5, or 15 unpredictable transitions between contexts, and item-in-context memory survived a 45min retention interval challenge. When the memory of item in context was put in conflict with non-episodic familiarity cues, rats relied on item in context using episodic memory. Our findings suggest that rats remember multiple unique events and the contexts in which these events occurred using episodic memory and support the view that rats may be used to model fundamental aspects of human cognition.

WAY 267,464, a non-peptide oxytocin receptor agonist, impairs social recognition memory in rats through a vasopressin 1A receptor antagonist action.

Recent in vitro studies suggest that the oxytocin receptor (OTR) agonist WAY 267,464 has vasopressin 1A receptor (V1AR) antagonist effects. This might limit its therapeutic potential due to the positive involvement of the V1AR in social behavior. The objective of this study was to assess functional V1AR antagonist-like effects of WAY 267,464 in vivo using a test of social recognition memory. Adult experimental rats were tested for their recognition of a juvenile conspecific rat that they had briefly met 30 or 120 min previously. The modulatory effects of vasopressin (AVP), the selective V1AR antagonist SR49059, and WAY 267,464 were examined together with those of the selective OTR antagonist Compound 25 (C25). Drugs were administered immediately after the first meeting. Control rats showed recognition of juveniles at a 30 min, but not a 120 min retention interval. AVP (0.005, but not 0.001 mg/kg intraperitoneal (i.p.)) improved memory such that recognition was evident after 120 min. This was prevented by pretreatment with SR49059 (1 mg/kg) and WAY 267,464 (10, 30, and 100 mg/kg). Given alone, SR49059 (1 mg/kg) and WAY 267,464 (30 and 100 mg/kg) impaired memory at a 30 min retention interval. The impairment with WAY 267,464 was not prevented by C25 (5 mg/kg), suggesting V1AR rather than OTR mediation of the effect. Given alone, C25 also impaired memory. These results highlight a tonic role for endogenous AVP (and oxytocin) in social recognition memory and indicate that WAY 267,464 functions in vivo as a V1AR antagonist to prevent the memory-enhancing effects of AVP.

The effects of exposure to dynamic expressions of affect on 5-month-olds’ memory

The purpose of this study was to examine the behavioral effects of adults’ communicated affect on 5-month-olds’ visual recognition memory. Five-month-olds were exposed to a dynamic and bimodal happy, angry, or neutral affective (face–voice) expression while familiarized to a novel geometric image. After familiarization to the geometric image and exposure to the affective expression, 5-month-olds received either a 5-min or 1-day retention interval. Following the 5-min retention interval, infants exposed to the happy affective expressions showed a reliable preference for a novel geometric image compared to the recently familiarized image. Infants exposed to the neutral or angry affective expression failed to show a reliable preference following a 5-min delay. Following the 1-day retention interval, however, infants exposed to the neutral expression showed a reliable preference for the novel geometric image. These results are the first to demonstrate that 5-month-olds’ visual recognition memory is affected by the presentation of affective information at the time of encoding.

The role of the dorsal dentate gyrus in object and object-context recognition

The aim of this study was to determine the role of the dorsal dentate gyrus (dDG) in object recognition memory using a black box and object-context recognition memory using a clear box with available cues that define a spatial context. Based on a 10min retention interval between the study phase and the test phase, the results indicated that dDG lesioned rats are impaired when compared to controls in the object-context recognition test in the clear box. However, there were no reliable differences between the dDG lesioned rats and the control group for the object recognition test in the black box. Even though the dDG lesioned rats were more active in object exploration, the habituation gradients did not differ. These results suggest that the dentate gyrus lesioned rats are clearly impaired when there is an important contribution of context. Furthermore, based on a 24h retention interval in the black box the dDG lesioned rats were impaired compared to controls.