Search

Could learning that uses cognitive control to judiciously use relevant information while ignoring distractions generally improve brain function, beyond forming explicit memories? According to a neuroplasticity hypothesis for how some cognitive behavioural therapies are effective, cognitive control training (CCT) changes neural circuit information processing1–3. Here we investigated whether CCT persistently alters hippocampal neural circuit function. We show that mice learned and remembered a conditioned place avoidance during CCT that required ignoring irrelevant locations of shock. CCT facilitated learning new tasks in novel environments for several weeks, relative to unconditioned controls and control mice that avoided the same place during reduced distraction. CCT rapidly changes entorhinal cortex-to-dentate gyrus synaptic circuit function, resulting in an excitatory–inhibitory subcircuit change that persists for months. CCT increases inhibition that attenuates the dentate response to medial entorhinal cortical input, and through disinhibition, potentiates the response to strong inputs, pointing to overall signal-to-noise enhancement. These neurobiological findings support the neuroplasticity hypothesis that, as well as storing item–event associations, CCT persistently optimizes neural circuit information processing. Studies in mice show that cognitive control training rapidly improves brain circuit function and enhances subsequent learning, which both persist for months.

Introduction Alcohol consumption on college campuses is a major public health concern. Extant literature has identified trauma exposure as a robust risk factor for problematic alcohol use in this at-risk population. However, the mechanisms underlying this association are less well-studied. Research indicates that bodily arousal is a fundamental feature of trauma exposure, and posits that internal stimuli (e.g., heart pounding) at the time of trauma may manifest into conditioned cues that can trigger posttraumatic responding and related symptomatology, including alcohol use. However, past work supporting these assertions has used paradigms purposefully designed to evoke memories of the trauma, making it difficult to ascertain whether the mechanism driving subsequent alcohol craving is the explicit memory cue or the associated bodily arousal. Methods The current study examined whether an implicit, trauma-relevant cue of bodily arousal (via voluntary hyperventilation) – independent of any explicit memory cue – would elicit increased desire to drink among 104 (Mage = 20.30; 61.5% female) trauma-exposed undergraduates. Results Results found no statistically significant difference in change in alcohol craving between the hyperventilation and control tasks. However, secondary analyses indicated that trauma type (i.e., interpersonal/non-interpersonal) may play an influential role in this relationship. More specifically, individuals reporting interpersonal trauma as their most traumatic event evidenced a significantly greater increase in desire to drink following hyperventilation compared to the non-interpersonal index trauma group. Discussion Generally, these findings suggest that bodily arousal may only serve as an implicit, trauma-relevant interoceptive cue that increases desire to drink within a specific subset of trauma-exposed college students (i.e., individuals indexing interpersonal trauma). Replication and extension are needed to further understand the influence of bodily arousal on subsequent alcohol use behavior, which will be critical to PTSD-alcohol use modeling and, ultimately, help in informing prevention- and treatment-oriented intervention efforts aimed at reducing problematic alcohol use on college campuses.

BACKGROUND Specific cognitive alterations could be one of the predictors that lead to the complex activities of daily living (CADL) impairment in mild cognitive impairment (MCI) and, hence, help to explain the continuum between MCI and dementia. OBJECTIVE We aimed to reevaluate the existing uncertainty regarding the impact of memory and executive functions on CADL in patients with MCI. METHODS Caregivers of 161 patients with amnestic multi-domain MCI and of 150 patients with incipient Alzheimer's disease as well as 100 age-, sex-, and education-matched controls, completed the Interview for Deterioration in Daily Living Activities in Dementia, a suitable instrument for the description and discrimination of CADL. In addition, all patients and controls were assessed with a neuropsychological battery to measure explicit memory and executive functions performance. RESULTS Multiple regression analyses showed that in the group of patients with amnestic multi-domain MCI, 67.4% of the variability of the CADL impairment was explained by worse performance on executive functions tests (p

The neuro-physiological response to stress has far-reaching implications for learning and memory processes. Here, we examined whether and how the stress-induced release of cortisol, following the socially-evaluated cold pressor test, influenced the acquisition of preferences in an evaluative conditioning (EC) procedure. We found that when the stressor preceded the evaluation phase, cortisol responders showed decreased evaluative conditioning effects. By contrast, impairing effects of a stressor-induced cortisol release before encoding were not found. Moreover, explicit memory was not found to be affected by the stressor or its timing. Implications of the timing-dependent effects of stress-induced cortisol release on EC and the relation between stress and associative memory are discussed.

Objective: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.Method: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.Results:Both groups showed reduced forgetting of the names that repeated as distraction and enhanced recollection of these pairs.Conclusions:The results demonstrate that passive methods to prompt automatic retrieval of associations may hold promise as interventions for people with early signs of AD.

Objective To evaluate the cognitive function of Chinese patients with Parkinson's disease PD postsubthalamic nucleus deep brain stimulation (STN‐DBS). Methods Cognitive function was assessed by neuropsychological methods in PD patients. Twenty matched healthy persons served as normal controls. t test, analysis of variance, and chi‐square analysis were used to compare the difference among the groups. Reliable change index was utilized to analyze the changes in cognition from the individual level. Results (a) Improvement in motor function was significantly better after STN‐DBS (P

A single subanesthetic infusion of ketamine can rapidly alleviate symptoms of treatment-resistant major depression. Since repeated administration is required to sustain symptom remission, it is important to characterize the potential untoward effects of prolonged ketamine exposure. While studies suggest that ketamine can alter cognitive function, it is unclear to what extent these effects are modulated by the frequency or chronicity of treatment. To test this, male and female adolescent (postnatal day [PD] 35) and adult (PD 60) BALB/c mice were treated for four consecutive weeks, either daily or thrice-weekly, with (R,S)-ketamine (30 mg/kg, intraperitoneal) or its biologically active metabolite, (2R,6R)-hydroxynorketamine (HNK; 30 mg/kg, intraperitoneal). Following drug cessation, memory performance was assessed in three operationally distinct tasks: (1) novel object recognition to assess explicit memory, (2) Y-maze to assess working memory, and (3) passive avoidance to assess implicit memory. While drug exposure did not influence working memory performance, thrice-weekly ketamine and daily (2R,6R)-HNK led to explicit memory impairment in novel object recognition independent of sex or age of exposure. Daily (2R,6R)-HNK impaired implicit memory in the passive-avoidance task whereas thrice-weekly (2R,6R)-HNK tended to improve it. These differential effects on explicit and implicit memory possibly reflect the unique mechanisms by which ketamine and (2R,6R)-HNK alter the functional integrity of neural circuits that subserve these distinct cognitive domains, a topic of clinical and mechanistic relevance to their antidepressant actions. Our findings also provide additional support for the importance of dosing frequency in establishing the cognitive effects of repeated ketamine exposure.

Background Despite the well-known clinical effects of midazolam and ketamine, including sedation and memory impairment, the neural mechanisms of these distinct drugs in humans are incompletely understood. The authors hypothesized that both drugs would decrease recollection memory, task-related brain activity, and long-range connectivity between components of the brain systems for memory encoding, pain processing, and fear learning. Methods In this randomized within-subject crossover study of 26 healthy adults, the authors used behavioral measures and functional magnetic resonance imaging to study these two anesthetics, at sedative doses, in an experimental memory paradigm using periodic pain. The primary outcome, recollection memory performance, was quantified with d′ (a difference of z scores between successful recognition versus false identifications). Secondary outcomes were familiarity memory performance, serial task response times, task-related brain responses, and underlying brain connectivity from 17 preselected anatomical seed regions. All measures were determined under saline and steady-state concentrations of the drugs. Results Recollection memory was reduced under midazolam (median [95% CI], d′ = 0.73 [0.43 to 1.02]) compared with saline (d′ = 1.78 [1.61 to 1.96]) and ketamine (d′ = 1.55 [1.12 to 1.97]; P < 0.0001). Task-related brain activity was detected under saline in areas involved in memory, pain, and fear, particularly the hippocampus, insula, and amygdala. Compared with saline, midazolam increased functional connectivity to 20 brain areas and decreased to 8, from seed regions in the precuneus, posterior cingulate, and left insula. Compared with saline, ketamine decreased connectivity to 17 brain areas and increased to 2, from 8 seed regions including the hippocampus, parahippocampus, amygdala, and anterior and primary somatosensory cortex. Conclusions Painful stimulation during light sedation with midazolam, but not ketamine, can be accompanied by increased coherence in brain connectivity, even though details are less likely to be recollected as explicit memories. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

International audience; Influence of loudness on sound recognition was investigated in an explicit memory experiment based on a conscious recollection-test phase-of previously encoded information-study phase. Three encoding conditions were compared: semantic (sounds were sorted in three different categories), sensory (sounds were rated in loudness), and control (participants were solely asked to listen to the sounds). Results revealed a significant study-to-test change effect: loudness change between the study and the test phases affects recognition. The effect was not specific to the encoding condition (semantic vs sensory) suggesting that loudness is an important hint for everyday sounds recognition. [Q-JF] Date

Evaluative conditioning (EC) is a change in the liking of a stimulus (conditioned stimulus or CS) due to its previous pairings with another stimulus (unconditioned stimulus or US). In three experiments, we investigated if conditioning CSs with fear or disgust evoking USs increase EC effects that do not require explicit memory. Experiment 1 used images to manipulate the type of US between participants, Experiment 2 used auditory stimuli to manipulate the type of US within participants, and Experiment 3 used both images and auditory stimuli to manipulate the type of US within participants. All experiments failed to provide evidence that fear/disgust-evoking USs lead to larger EC effects without explicit memory than non-fear/non-disgust-evoking USs. Most results are in line with the assumption that the found EC effects are based on explicit memory. The results contribute to the larger goal in EC research of determining which conditions can lead to EC effects in the absence of explicit memory.

The extent to which explicit memory (EM) and implicit memory (IM) involve similar or differential neural substrates remains unclear. To address this issue, this study provides a direct, meta-analytic comparison of functional neuroimaging studies involving EM and IM tasks. The meta-analysis comprised two separate meta-analytic comparisons. First, to compare EM and IM in terms of encoding activity, subsequent memory effects (remembered > forgotten) and repetition suppression effects (first > repeated) were directly compared. Second, to compare EM and IM in terms of retrieval activity, retrieval success effects (hit > correct rejection) and repetition suppression effects were directly compared. Based on the notion that reduced activity during repeated processing is a ‘by-product’ or direct consequence of the stimulus processing performed in the same regions at initial exposure, regions showing repetition suppression were thought to play an important role in both IM-encoding and IM-retrieval activities. The results indicated that subsequent memory and repetition suppression effects had extensive overlaps and no significant separations, suggesting that EM- and IM-encoding activities involve largely common regions. Retrieval success and repetition suppression effects had strong segregations and only modest overlaps, suggesting that EM- and IM-retrieval activities involve largely separate regions. Consistent with these results, Explicit/Implicit Memory Encoding and Retrieval (EIMER), a neurocognitive model of EM and IM that suggests a common-encoding, separate-retrieval hypothesis for EM and IM is proposed herein.

When we seek to forget unwelcome memories, does the suppressed content still exert an unconscious influence on our thoughts? Although intentionally stopping retrieval of a memory reduces later episodic retention for the suppressed trace, it remains unclear the extent to which suppressed content persists in indirectly influencing mental processes. Here we tested whether inhibitory control processes underlying retrieval suppression alter the influence of a memory’s underlying semantic content on later thought. To achieve this, across two experiments, we tested whether suppressing episodic retrieval of to-be-excluded memories reduced the indirect expression of the unwanted content on an apparently unrelated test of creative problem solving: the remote associates test (RAT). Experiment 1 found that suppressed content was less likely than unsuppressed content to emerge as solutions to RAT creativity problems. Indeed, suppression abolished evidence of conceptual priming, even when participants reported no awareness of the relationship between the memory and the creativity tasks. Experiment 2 replicated this effect and also found that directing participants to use explicit memory to solve RAT problems eliminated suppression effects. Experiment 2 thus rules out the possibility that suppression effects reflect contamination by covert explicit retrieval strategies. Together, our results indicate that inhibitory control processes underlying retrieval suppression not only disrupt episodic retention, but also reduce the indirect influence of suppressed semantic content during unrelated thought processes. Considered with other recent demonstrations of implicit suppression effects, these findings indicate that historical assumptions about the persisting influence of suppressed thoughts on mental health require closer empirical scrutiny and need to be reconsidered.

Speakers tailor referential expressions to the listener's knowledge, a phenomenon called audience design. Audience design requires access to partner-specific representations in memory, which could be compromised among older adults who experience memory declines. In fact, little is known about how the memory representation of shared knowledge with a conversational partner influences audience design in multiparty conversation. We examined how young and older adults tailor their utterances for partners holding different representations of the same item. Both younger and older adults successfully adjusted their referential expressions to the current partner's knowledge state in a live conversation. However, when memory was explicitly probed, older adults showed a source memory deficit in distinguishing which partner held which label. These results suggest that explicit memory may not be necessary for audience design, and that implicit memory processes, which are preserved with aging, may contribute to effective audience design. The findings highlight a pathway to preserved communicative competence with aging and the roles of multiple memory systems including both implicit and explicit systems. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Previous studies have evidenced cognitive difficulties across various domains in Type 1 Diabetes Mellitus (T1DM) children, but the implicit memory system has not yet been systematically explored.Taking into account that the interplay between memory and perception may be modulated by the semantic category of the stimuli and their salience, we explored explicit and implicit memory using both object and food stimuli to verify whether for T1DM children there is a feebleness in performing the function of memory as a function of the stimuli used.Eighteen T1DM children and 47 healthy children performed an explicit recognition task in which they were requested to judge whether the presented image had already been shown ("old") or not ("new") and an identification priming task in which they were asked to name new and old pictures presented at nine ascending levels of spatial filtering.Results did not reveal any differences between controls and T1DM children in the explicit memory recognition task, whereas some differences between the two groups were found in the identification priming task. In T1DM children, the priming effect was observed only for food images.The dissociation between implicit and explicit memory observed in children with diabetes seems to be modulated by the category of the stimuli, and these results underscore the relevance of taking into account this variable when exploring cognitive functions.

We tested the influence of misinformation on evaluative conditioning (EC) by giving false information about the contingencies between CS and US stimuli after a conditioning procedure. This was done by asking participants questions about the USs while inaccurately suggesting that some CSs had been paired with a US that had the opposite valence than the US it had actually been paired with. For CS-US pairs from other conditions, accurate suggestions or no suggestions at all were given to participants. This manipulation significantly moderated EC effects. For pairs that were combined with inaccurate information we found a reversed EC effect, while we found a standard EC effect for both pairs combined with no suggestions and pairs combined with accurate suggestions. Additional analyses showed that the misinformation manipulation also moderated memory for the pairs. These results show that misinformation manipulations cannot only influence explicit memory but also attitudes. Furthermore, and in line with some theories of EC, they support the relevance of explicit memory for EC effects.

The entorhinal–hippocampal circuit is one of the earliest sites of cortical pathology in Alzheimer's disease (AD). Visuospatial memory paradigms that are mediated by the entorhinal–hippocampal circuit may offer a means to detect memory impairment during the early stages of AD. In this study, we developed a 4-min visuospatial memory paradigm called VisMET (Visuospatial Memory Eye-Tracking Task) that passively assesses memory using eye movements rather than explicit memory judgements. We had 296 control or memory-impaired participants view a set of images followed by a modified version of the images with either an object removed, or a new object added. Healthy controls spent significantly more time viewing these manipulations compared to subjects with mild cognitive impairment and AD. Using a logistic regression model, the amount of time that individuals viewed these manipulations could predict cognitive impairment and disease status with an out of sample area under the receiver–operator characteristic curve of 0.85. Based on these results, VisMET offers a passive, sensitive, and efficient memory paradigm capable of detecting objective memory impairment and predicting cognitive and disease status.

Contains fulltext : 208816.pdf (Publisher’s version ) (Open Access) PURPOSE: Sleep deprivation is associated with increased forgetting of declarative memories. Sleep restriction across multiple consecutive nights is prevalent in adolescents, but questions remain as to whether this pattern of sleep impairs memory for material typically learned in the classroom and the time course of retention beyond a few days. METHODS: Adolescents aged 15-18 years (n = 29) were given 5 hours sleep opportunity each night for 5 consecutive nights (sleep restricted group; SR), simulating a school week containing insufficient sleep. After the fourth night of restriction, participants learned detailed facts about different species of arthropod across a 6-hour period. Retention was tested 30 minutes and 3 days after learning and contrasted with a control group (n = 30) who had 9 hours sleep opportunity every night of the study. A subset of participants (SR, n = 14; control, n = 22) completed a surprise test 42 days after learning. RESULTS: Memory was significantly impaired in the SR group relative to controls, with 26% increased forgetting at the 30-minute test (t(57) = 2.54, p = .014, d = .66), 34% at the Day 3 test (t(57) = 2.65, p = .010, d = .69), and 65% at the Day 42 test (t(34) = 3.22, p = .003, d = 1.17). Vigilance was also significantly impaired after 4 nights of restricted sleep (p < .05), but did not correlate significantly with memory (p > .05). CONCLUSION: Long-term retention of classroom material is significantly compromised when adolescents learn after being sleep restricted, reinforcing the importance of keeping good sleep habits to optimize learning.

When people suppress retrieval of episodic memories, it can induce forgetting on later direct tests of memory for those events. Recent reports indicate that suppressing retrieval affects less conscious, unintentional retrieval of unwanted memories as well, at least on perceptually-oriented indirect tests. In the current study we examined how suppressing retrieval affects conceptual implicit memory for the suppressed content, using a category verification task. Participants studied cue-target words pairs in which the targets were exemplars of 22 semantic categories, such as vegetables or occupations. They then repeatedly retrieved or suppressed the targets in response to the cues for some of those pairs. Afterwards, they were exposed to the targets intermixed with novel items, one at a time, and asked to verify the membership of each of the words in a semantic category, as quickly as possible. Judgment response times to studied words were faster than to unstudied exemplars, reflecting repetition priming, as has been previously observed. Strikingly, the beneficial effects of prior exposure on response time were eliminated for targets that had been suppressed. Follow-up explicit memory tests also demonstrated that retrieval suppression continued to disrupt episodic recall for the items that had been just been re-exposed on the category verification test. These findings support the contention that the effects of retrieval suppression are not limited to episodic memory, but also affect indirect expressions of those memories on conceptually oriented tests, raising the possibility that underlying semantic representations of suppressed content are affected.

Visual statistical learning (VSL) refers to the learning of environmental regularities. Classically considered an implicit process, one patient with isolated hippocampal damage is severely impaired at VSL tasks, suggesting involvement of explicit memory. Here, we asked whether memory impairment (MI) alone, absent of clear hippocampal pathology, predicted deficits across different VSL tasks. A classic VSL task revealed no learning in MI participants (Exp. 1), while imposing attentional demands (Exp. 2: flicker detection, Exp. 3: gender/location categorization) during familiarization revealed modest residual VSL. MI with nonspecific neural correlates predicted impaired VSL overall, but attentional processes may be harnessed for rehabilitation.

Structural priming is the tendency to repeat syntactic structure across sentences and can be divided into short-term (prime to immediately following target) and long-term (across an experimental session) components. Current theories of structural priming propose that different memory systems support these components, however, this study investigates how non-declarative memory could support both the transient, short-term and the persistent, long-term structural priming effects commonly seen in the literature. We propose that these characteristics are supported by different subcomponents of non-declarative memory: Perceptual and conceptual non-declarative memory respectively. Previous studies have suggested that these subcomponents age differently, with only conceptual memory showing age-related decline. By investigating how different components of structural priming vary across the lifespan, we aim to elucidate how non-declarative memory supports two seemingly different components of structural priming. In 167 participants ranging between 20 and 85 years old, we find no change in short-term priming magnitude and performance on perceptual tasks, whereas both long-term priming and conceptual memory vary with age. We suggest therefore that the two seemingly different components of structural priming are supported by different components of non-declarative memory. These findings have important implications for theoretical accounts of structural priming.

Real-life decisions are often repeated. Whether considering taking a job in a new city, or doing something mundane like checking if the stove is off, decisions are frequently revisited even if no new information is available. This mode of behavior takes a particularly pathological form in obsessive-compulsive disorder (OCD), which is marked by individuals' redeliberating previously resolved decisions. Surprisingly, little is known about how information is transferred across decision episodes in such circumstances, and whether and how such transfer varies in OCD. In two experiments, data from a repeated decision-making task and computational modeling revealed that both implicit and explicit memories of previous decisions affected subsequent decisions by biasing the rate of evidence integration. Further, we replicated previous work demonstrating impairments in baseline decision-making as a function of self-reported OCD symptoms, and found that information transfer effects specifically due to implicit memory were reduced, offering computational insight into checking behavior.

Objective:Mobility limitation and cognitive decline are related. Metabolic syndrome (MetS), the clustering of three or more cardiovascular risk factors, is associated with decline in both mobility and cognition. However, the interrelationship among MetS, mobility, and cognition is unknown. This study investigated a proposed pathway where cognition moderates the relationship between MetS and Mobility.Method:Adults ages 45–90 years were recruited. MetS risk factors and mobility performance (Short Physical Performance Battery (SPPB) and gait speed) were evaluated. Cognition was assessed using a comprehensive neuropsychological battery. A factor analysis of neuropsychological test scores yielded three factors: executive function, explicit memory, and semantic/contextual memory. Multivariable linear regression models were used to examine the relationship among MetS, mobility, and cognition.Results:Of the 74 participants (average age 61 ± 9 years; 41% female; 69% White), 27 (36%) participants manifested MetS. Mean SPPB score was 10.9 ± 1.2 out of 12 and gait speed was 1.0 ± 0.2 m/s. There were no statistically significant differences in mobility by MetS status. However, increase in any one of the MetS risk factors was associated with decreased mobility performance after adjusting for age and gender (SPPB score: β (SE) -.17 (0.08), p < .05; gait speed: -.03 (.01), p < .01). Further adjusting for cognitive factors (SPPB score: explicit memory .31 (.14), p = .03; executive function 0.45 (0.13), p < .01; gait speed: explicit memory 0.04 (0.02), p = .03; executive function 0.06 (0.02), p < .01) moderated the relationships between number of metabolic risk factors and mobility.Conclusion:The relationship between metabolic risk factors and mobility may be moderated by cognitive performance, specifically through executive function and explicit memory.

Eye movements during visual search change with prior experience for search stimuli. Previous studies measured these gaze effects shortly after initial viewing, typically during free viewing; it remains open whether the effects are preserved across long delays and for goal-directed search, and which memory system guides gaze. In Experiment 1, we analyzed eye movements of healthy adults viewing novel and repeated scenes while searching for a scene-embedded target. The task was performed across different time points to examine the repetition effects in long-term memory, and memory types were grouped based on explicit recall of targets. In Experiment 2, an amnesic person with bilateral extended hippocampal damage and the age-matched control group performed the same task with shorter intervals to determine whether or not the repetition effects depend on hippocampal function. When healthy adults explicitly remembered repeated target-scene pairs, search time and fixation duration decreased, and gaze was directed closer to the target region, than when they forgot targets. These effects were seen even after a one-month delay from their initial viewing, suggesting the effects are associated with long-term, explicit memory. Saccadic amplitude was not strongly modulated by scene repetition or explicit recall of targets. The amnesic person did not show explicit recall or implicit repetition effects, whereas his control group showed similar patterns to those seen in Experiment 1. The results reveal several aspects of gaze control that are influenced by long-term memory. The dependence of gaze effects on medial temporal lobe integrity support a role for this region in predictive gaze control.

The adaption of movement to changes in the environment varies across life span. Recent evidence has linked motor adaptation and its reduction with age to differences in "explicit" learning processes. We examine differences in brain structure and cognition underlying motor adaptation in a population-based cohort (n = 322, aged 18-89 years) using a visuomotor learning task and structural magnetic resonance imaging. Reduced motor adaptation with age was associated with reduced volume in striatum, prefrontal, and sensorimotor cortical regions, but not cerebellum. Medial temporal lobe volume, including the hippocampus, became a stronger determinant of motor adaptation with age. Consistent with the role of the medial temporal lobes, declarative long-term memory showed a similar interaction, whereby memory was more positively correlated with motor adaptation with increasing age. By contrast, visual short-term memory was related to motor adaptation, independently of age. These results support the hypothesis that cerebellar learning is largely unaffected in old age, and the reduction in motor adaptation with age is driven by a decline in explicit memory systems.

Background Studies have found that individuals with mild cognitive impairment (MCI) exhibit a range of deficits outside the realm of primary explicit memory, yet the role of response speed and implicit learning in older adults with MCI have not been established. Objective The current study aims to explore and document response speed and implicit learning in older adults with neuropsychologically defined MCI using a simple serial reaction (SRT) task. In addition, the study aims to explore the feasibility of a novel utilization of the simple cognitive task using machine learning procedures as a proof of concept. Method Participants were 22 cognitively healthy older adults and 20 older adults with MCI confirmed through comprehensive neuropsychological evaluation. Two-sample t-test, multivariate regression, and mixed-effect models were used to investigate group difference in response speed and implicit learning on the SRT task. We also explored the potential utility of SRT feature analysis through random forest classification. Results With demographic variables controlled, the MCI group showed overall slower reaction time and higher error rate compared to the cognitively healthy volunteers. Both groups showed significant simple motor learning and implicit learning. The learning patterns were not statistically different between the two groups. Random forest classification achieved overall accuracy of 80.9%. Conclusions Individuals with MCI demonstrated slower reaction time and higher error rate compared to cognitively healthy volunteers but demonstrated largely preserved motor learning and implicit sequence learning. Preliminary results from random forest classification using features from SRT performance supported further research in this area.

The adaption of movement to changes in the environment varies across life span. Recent evidence has linked motor adaptation and its reduction with age to differences in “explicit” learning processes. We examine differences in brain structure and cognition underlying motor adaptation in a population-based cohort (n = 322, aged 18–89 years) using a visuomotor learning task and structural magnetic resonance imaging. Reduced motor adaptation with age was associated with reduced volume in striatum, prefrontal, and sensorimotor cortical regions, but not cerebellum. Medial temporal lobe volume, including the hippocampus, became a stronger determinant of motor adaptation with age. Consistent with the role of the medial temporal lobes, declarative long-term memory showed a similar interaction, whereby memory was more positively correlated with motor adaptation with increasing age. By contrast, visual short-term memory was related to motor adaptation, independently of age. These results support the hypothesis that cerebellar learning is largely unaffected in old age, and the reduction in motor adaptation with age is driven by a decline in explicit memory systems., Highlights • Reduced motor adaptation with age relates to less graey matter in motor regions. • These regions are striatum, premotor and prefrontal cortex, but not the cerebellum. • With age, motor adaptation is more positively related to medial temporal lobe areas. • Motor adaptation relates to short-term memory measures regardless of age. • With age, motor adaptation is more positively related to long-term memory scores.

Speakers’ memory of sentence structure can persist and modulate the syntactic choices of subsequent utterances (i.e., structural priming). Much research on structural priming posited a multifactorial account by which an implicit learning process and a process related to explicit memory jointly contribute to the priming effect. Here, we tested two predictions from that account: (1) that lexical repetition facilitates the retrieval of sentence structures from memory; (2) that priming is partly driven by a short-term explicit memory mechanism with limited resources. In two pairs of structural priming and sentence structure memory experiments, we examined the effects of structural priming and its modulation by lexical repetition as a function of cognitive load in native Dutch speakers. Cognitive load was manipulated by interspersing the prime and target trials with easy or difficult mathematical problems. Lexical repetition boosted both structural priming (Experiments 1a–2a) and memory for sentence structure (Experiments 1b–2b) and did so with a comparable magnitude. In Experiment 1, there were no load effects, but in Experiment 2, with a stronger manipulation of load, both the priming and memory effects were reduced with a larger cognitive load. The findings support an explicit memory mechanism in structural priming that is cue-dependent and attention-demanding, consistent with a multifactorial account of structural priming.

One explanation for why concrete words are recalled better than abstract words is systematic differences across these word types in the availability of context information. In contrast, explanations for the concrete-word advantage in recognition memory do not consider a possible role for context availability. We investigated the extent to which context availability can explain the effects of word concreteness in both free recall (Exp. 1) and item recognition (Exp. 2) by presenting each target word in isolation, in a low-constraint sentence context, or in a high-constraint sentence context at study. Concreteness effects were consistent with those from previous research, with concrete-word advantages in both tasks. Embedding words in sentence contexts with low semantic constraint hurt recall performance but helped recognition performance, relative to presenting words in isolation. Embedding words in sentence contexts with high semantic constraint hurt both recall and recognition performance, relative to words in low-constraint sentences. The effects of concreteness and semantic constraint were consistent for both high- and low-frequency words. Embedding words in high-constraint sentence contexts neither reduced nor eliminated the concreteness effect in recall or recognition, indicating that differences in context availability cannot explain concreteness effects in explicit memory.

Endel Tulving conducted pioneering work on the explicit and implicit memory systems and demonstrated that priming effects can be long-lasting. It is also well-established that emotion can amplify explicit and implicit memory. Prior work has utilized repetition suppression (RS) of the fMRI-BOLD signal—a reduction in the magnitude of activity over repeated presentations of stimuli—to index implicit memory. Using an explicit recognition memory paradigm, we examined emotional modulation of long-term implicit memory effects as revealed by repetition suppression (i.e., comparing second-exposure forgotten items to first-exposure correct rejections). Forty-seven participants incidentally encoded line-drawings of negative, positive, and neutral scenes followed by the full color image. Twenty-four hours later, participants underwent fMRI during a recognition memory test in which old and new line-drawings were presented. Implicit and explicit memory effects were defined by the contrasts of New-Correct Rejections > Old-Misses and Old-Hits > New-Correct Rejections, respectively. Wide-spread Negative RS was found in frontal and occipito-temporal cortex that was greater than Neutral RS in the right orbito-frontal cortex and inferior frontal gyri. Valence-specific Negative RS, compared to Positive RS, was observed in the left inferior occipital gyrus. There was no strong evidence for emotional modulation of amygdala RS, but functional connectivity analyses revealed valence-specificity: Negative and positive valence were associated with repetition suppression and repetition enhancement of amygdala-occipital connectivity, respectively. Negative implicit memory patterns in most frontal regions—but not occipital areas—overlapped with explicit memory effects. Thus, implicit memory effects for a single visual stimulus presentation are modulated by emotional valence, can be observed 24hours after initial exposure, and show some overlap with explicit memory.

The anterior thalamus is a key relay of neuronal signals within the limbic system. During sleep, the occurrence of hippocampal sharp wave-ripples (SWRs), believed to mediate consolidation of explicit memories, is modulated by thalamocortical network activity, yet how information is routed around SWRs and how this communication depends on neuronal dynamics remains unclear. Here, by simultaneously recording ensembles of neurons in the anterior thalamus and local field potentials in the CA1 area of the hippocampus, we show that the head-direction (HD) cells of the anterodorsal nucleus are set in stable directions immediately before SWRs. This response contrasts with other thalamic cells that exhibit diverse couplings to the hippocampus related to their intrinsic dynamics but independent of their anatomical location. Thus, our data suggest a specific and homogeneous contribution of the HD signal to hippocampal activity and a diverse and cell-specific coupling of non-HD neurons., Thalamic head direction (HD) cells are necessary to establish spatial maps in the hippocampus. Here, the authors show that HD cells tuned to a particular direction are coupled to individual hippocampal ripple events during sleep, suggesting an influence of the replay of specific trajectories during sleep memory consolidation.

The present study investigated the effect of encoding duration on implicit and explicit eyewitness memory. Participants (N = 227) viewed a mock crime (brief, 15-s vs. long, 30-s vs. irrelevant/control) and were then tested with both implicit and explicit memory prompts or with explicit memory prompts only. Brief-encoding participants revealed more critical details implicitly than long-encoding or control participants. Further, the number and percentage of accurate details recalled explicitly were higher for long-encoding than for brief-encoding participants. Implicit testing prior to explicit recall—as compared to completing a filler task—was detrimental to free recall performance. Interestingly, brief-encoding participants were significantly more likely to remember critical details implicitly but not explicitly than long-encoding participants. This is the first study to investigate implicit eyewitness memory for a multimodal mock crime. Findings are theoretically consistent with prior research on cognition while expanding upon the extant eyewitness memory and investigative interviewing literature.

Humans are very good at remembering large numbers of scenes over substantial periods of time. But how good are they at remembering changes to scenes? In this study, we tested scene memory and change detection two weeks after initial scene learning. In Experiments 1-3, scenes were learned incidentally during visual search for change. In Experiment 4, observers explicitly memorized scenes. At test, after two weeks observers were asked to discriminate old from new scenes, to recall a change that they had detected in the study phase, or to detect a newly introduced change in the memorization experiment. Next, they performed a change detection task, usually looking for the same change as in the study period. Scene recognition memory was found to be similar in all experiments, regardless of the study task. In Experiment 1, more difficult change detection produced better scene memory. Experiments 2 and 3 supported a "depth-of-processing" account for the effects of initial search and change detection on incidental memory for scenes. Of most interest, change detection was faster during the test phase than during the study phase, even when the observer had no explicit memory of having found that change previously. This result was replicated in two of our three change detection experiments. We conclude that scenes can be encoded incidentally as well as explicitly and that changes in those scenes can leave measurable traces even if they are not explicitly recalled.

Older adults often show greater implicit/unconscious memory than young adults for incidental information that was task-irrelevant during its acquisition. Shallow/perceptual encoding by older adults may boost performance on implicit tasks that reinstate this type of processing, whereas deeper/conceptual encoding by young adults may support greater explicit/conscious memory. To test this, young and older participants were exposed to incidental words in a text color identification task before the trial-by-trial capture of priming and recognition. In Experiments 1-3 priming and recognition were significantly greater in young than older adults, providing evidence against age differences in encoding style. In Experiments 2-3 older adults were more liberal than young adults in making positive recognition judgments to incidental relative to intentional items, even though source memory was poor in both groups. Findings pinpoint age differences in the utilization of previously incidental versus intentional information on different types of task.

In 2006 Mitchell demonstrated that implicit memory was robust to decay. He showed that the ability to identify fragments of pictures seen 17 years before was significantly higher than for new stimuli. Is this true only for implicit memory? In this study, we tested whether explicit memory was still possible for drawings (n = 144) that had been presented once or three times, two seconds each time on average, approximately 12 years earlier. Surprisingly, our data reveal that our participants were able to recognize pictures above chance level. Preserved memory was mainly observed in the youngest subjects, for stimuli seen three times. Despite the fact that confidence judgments were low, reports suggest that recognition could be based on a strong sense of familiarity. These data extend Mitchell's findings and show that familiarity can also be robust to decay.

Episodic memory undergoes dramatic improvement in early childhood; the reason for this is poorly understood. In adults, episodic memory relies on a distributed neural network. Key brain regions that supporting these processes include the hippocampus, portions of the parietal cortex, and portions of prefrontal cortex, each of which shows different developmental profiles. Here we asked whether developmental differences in the axonal pathways connecting these regions may account for the robust gains in episodic memory in young children. Using diffusion weighted imaging, we examined whether white matter connectivity between brain regions implicated in episodic memory differed with age, and were associated with memory performance differences in 4- and 6-year-old children. Results revealed that white matter connecting the hippocampus to the inferior parietal lobule significantly predicted children’s performance on episodic memory tasks. In contrast, variation in the white matter connecting the hippocampus to the medial prefrontal cortex did not relate to memory performance. These findings suggest that structural connectivity between the hippocampus and lateral parietal regions is relevant to the development of episodic memory. Keywords: White matter, Memory development, Episodic memory, Diffusion weighted imaging

In human scalp EEG recordings, both sustained potentials and alpha-band oscillations are present during the delay period of working memory tasks and may therefore reflect the representation of information in working memory. However, these signals may instead reflect support mechanisms rather than the actual contents of memory. In particular, alpha-band oscillations have been tightly tied to spatial attention and may not reflect location-independent memory representations per se. To determine how sustained and oscillating EEG signals are related to attention and working memory, we attempted to decode which of 16 orientations was being held in working memory by human observers (both women and men). We found that sustained EEG activity could be used to decode the remembered orientation of a stimulus, even when the orientation of the stimulus varied independently of its location. Alpha-band oscillations also carried clear information about the location of the stimulus, but they provided little or no information about orientation independently of location. Thus, sustained potentials contain information about the object properties being maintained in working memory, consistent with previous evidence of a tight link between these potentials and working memory capacity. In contrast, alpha-band oscillations primarily carry location information, consistent with their link to spatial attention.SIGNIFICANCE STATEMENTWorking memory plays a key role in cognition, and working memory is impaired in several neurological and psychiatric disorders. Previous research has suggested that human scalp EEG recordings contain signals that reflect the neural representation of information in working memory. However, to conclude that a neural signal actually represents the object being remembered, it is necessary to show that the signal contains fine-grained information about that object. Here, we show that sustained voltages in human EEG recordings contain fine-grained information about the orientation of an object being held in memory, consistent with a memory storage signal.

While a lot is known about the mechanisms promoting aversive learning, the impact of rewarding factors on memory has received comparatively less attention. This research investigates reward-related explicit memory in male rats, by taking advantage of the emotional-object recognition test. This is based on the prior association, during conditioned learning, between a rewarding experience (the encounter with a receptive female rat) and an object; afterwards rat discrimination and recognition of the â emotional objectâ is recorded in the presence of a novel object, as a measure of positive limbic memory formation. Since endocannabinoids are critical for processing reward and motivation, the consequences of the stimulation of cannabinoid signalling are also assessed by the administration of WIN 55,212-2 at pre- and post-conditioning time. Our results show that rats encode the association between object and rewarding experience, form positive limbic memory of the emotional object, and retrieve this information in the face of novelty. Stimulation of the cannabinoid system at pre-conditioning time is able to strengthen reward-related explicit memory in the presence of novelty, whereas post-conditioning activation increases approach behaviour to novel stimuli. The assessment of limbic memory by the emotional-object recognition test can help unveiling the addictive and confounding properties of psychotropic drugs.

Recognition judgments can benefit from the use of environmental cues that signal the general likelihood of encountering familiar versus unfamiliar stimuli. While incorporating such cues is often adaptive, there are circumstances (e.g., eyewitness testimony) in which observers should fully ignore environmental cues in order to preserve memory report fidelity. The current studies used the explicit memory cueing paradigm to examine whether participants could intentionally ignore reliable environmental cues when instructed. Three experiments demonstrated that participants could volitionally dampen the directional influence of environmental cues on their recognition judgments (i.e., whether influenced to respond "old" or "new") but did not fully eliminate their influence. Although monetary incentives diminished the mean influence of cues on responses rates, finer grained individual differences analysis, as well as confidence and RTs analyses, demonstrated that participants were still systematically influenced. These results demonstrate that environmental cues presented at test remain a potent influence on recognition decisions and subjective confidence even when ostensibly ignored. (PsycINFO Database Record

The basolateral amygdala (BLA) is a critical site for the reconsolidation of labile contextual cocaine memories following retrieval-induced reactivation/destabilization. Here, we examined whether glucocorticoid receptors (GR), which are abundant in the BLA, mediate this phenomenon. Rats were trained to lever press for cocaine reinforcement in a distinct environmental context, followed by extinction training in a different context. Rats were then briefly exposed to the cocaine-paired context (to elicit memory reactivation and reconsolidation) or their home cages (no reactivation control). Exposure to the cocaine-paired context elicited greater serum corticosterone concentrations than home cage stay. Interestingly, the GR antagonist, mifepristone (3-10 ng/hemisphere), administered into the BLA after memory reactivation produced a further, dose-dependent increase in serum corticosterone concentrations during the putative time of cocaine-memory reconsolidation but produced an inverted U-shaped dose-effect curve on subsequent cocaine-seeking behavior 72 h later. This effect was anatomically selective, dependent on memory reactivation (i.e., not observed after home cage exposure), and did not reflect protracted hyperactivity. However, the effect was also observed when mifepristone was administered after novelty stress that mimics drug context-induced hypothalamic-pituitary-adrenal (HPA) axis activation without explicit memory reactivation. Together, these findings suggest that, similar to explicit memory retrieval, a stressful event is sufficient to destabilize cocaine memories and permit their manipulation. Furthermore, BLA GR stimulation exerts inhibitory feedback upon HPA axis activation and thus suppresses cocaine-memory reconsolidation.

Correctly understood speech in difficult listening conditions is often difficult to remember. A long-standing hypothesis for this observation is that the engagement of cognitive resources to aid speech understanding can limit resources available for memory encoding. This hypothesis is consistent with evidence that speech presented in difficult conditions typically elicits greater activity throughout cingulo-opercular regions of frontal cortex that are proposed to optimize task performance through adaptive control of behavior and tonic attention. However, successful memory encoding of items for delayed recognition memory tasks is consistently associated with increased cingulo-opercular activity when perceptual difficulty is minimized. The current study used a delayed recognition memory task to test competing predictions that memory encoding for words is enhanced or limited by the engagement of cingulo-opercular activity during challenging listening conditions. An fMRI experiment was conducted with twenty healthy adult participants who performed a word identification in noise task that was immediately followed by a delayed recognition memory task. Consistent with previous findings, word identification trials in the poorer signal-to-noise ratio condition were associated with increased cingulo-opercular activity and poorer recognition memory scores on average. However, cingulo-opercular activity decreased for correctly identified words in noise that were not recognized in the delayed memory test. These results suggest that memory encoding in difficult listening conditions is poorer when elevated cingulo-opercular activity is not sustained. Although increased attention to speech when presented in difficult conditions may detract from more active forms of memory maintenance (e.g., sub-vocal rehearsal), we conclude that task performance monitoring and/or elevated tonic attention supports incidental memory encoding in challenging listening conditions.

Retrograde amnesia (RA), which includes loss of memory for past personal events (autobiographical RA) and for acquired knowledge (semantic RA), has been largely documented in patients with amnestic mild cognitive impairment (aMCI). However, previous studies have produced controversial results particularly concerning the temporal extent of memory impairment. Here we investigated whether, with the onset of hippocampal pathology, age of memory acquisition and retrieval frequency play different roles in modulating the progressive loss of semantic and episodic contents of retrograde memory respectively. For this purpose, aMCI patients and healthy controls were tested for the ability to recall semantic and autobiographical information related to famous public events as a function of both age of acquisition and retrieval frequency. In aMCI patients, we found that the impairment in recollecting past personal incidents was modulated by the combined action of memory age and retrieval frequency, because older and more frequently retrieved episodes are less susceptible to loss than more recent and less frequently retrieved ones. On the other side, we found that the loss of semantic information depended only on memory age, because the remoteness of the trace allows for better preservation of the memory. Our results provide evidence that the loss of the two components of retrograde memory is regulated by different mechanisms. This supports the view that diverse neural mechanisms are involved in episodic and semantic memory trace storage and retrieval, as postulated by the Multiple Trace Theory.

Metamemory entails cognitively assessing the strength of one’s memories. We tested the ability of nine Long-Evans rats to distinguish between remembering and forgetting by presenting a decline option that allowed a four-choice odor-based delayed match to sample (DMTS) tests to be by-passed. Rats performed significantly better on tests they chose to take than on tests they were forced to take, indicating metacognitive responding. However, rather than control by internal mnemonic cues, one alternative explanation is that decline use is based on external test-specific cues that become associated with increased rewards overtime. To examine this possibility, we tested rats on three generalization tests in which external contingencies were inconsistent and therefore could not serve as discriminative cues. Rats transferred adaptive use of the decline response in tests that eliminated memory by presenting no sample, increased memory by presenting multiple samples, and both weakened and strengthened memory by varying the retention interval. Further, subjects chose to take or decline the test before encountering the memory test, providing evidence that rats based their metacognitive responding on internal cues rather than external ones. To our knowledge, this is the first robust evidence for metamemory in rats using the DMTS decline-test paradigm in which several possible sources of external stimulus control can be ruled out.

Using implicit tests, older adults have been found to retain conceptual knowledge of previously seen task-irrelevant information. While younger adults typically do not show the same effect, evidence from one study [Gopie, N., Craik, F. I. M., & Hasher, L. (2011). A double dissociation of implicit and explicit memory in younger and older adults. Psychological Science, 22, 634–640. doi:10.1177/0956797611403321] suggests otherwise. In that study, young adults showed greater explicit than implicit memory for previous distractors on a word fragment completion task. This was interpreted as evidence for maintaining access to previous conceptual knowledge of the distractors. Here, we report two failures to replicate that original finding, followed by a third study designed to test directly whether young adults use conceptual-level information that was previously irrelevant. Our findings agree with others that young adults show weak to no evidence of conceptual knowledge of previously irrelevant information.

Recent work has suggested that the benefits of sleep for memory consolidation are enhanced for highly salient (versus non-salient) memories. Using a technique known as targeted memory reactivation, it is possible to selectively strengthen newly learned memories by re-exposing the sleeping brain to auditory cues. The aim of the current study was to examine whether emotionally salient memories are also more responsive to targeted memory reactivation in slow-wave sleep than neutral memories. In an initial training phase, participants memorised emotionally negative and neutral pictures, which were each paired with a semantically related sound. Recognition for the pictures was assessed before and after a 90-min nap opportunity, during which half the sounds were re-presented during slow-wave sleep (as assessed via online polysomnographic sleep monitoring). We observed no effect of targeted memory reactivation on the recognition of emotionally negative or neutral memories. Our results highlight the importance of the memory paradigm used to assess targeted memory reactivation, and suggest that the robust and durable nature of recognition memory may make it an insensitive measure of behavioural targeted memory reactivation benefits. To fully assess the impacts of targeted memory reactivation on emotional memory processing in sleep, future studies should adopt experimental paradigms that maximise the salience of emotional stimuli while also providing a sensitive index of memory accuracy.

Neuroimaging data indicate that episodic memory (i.e., remembering specific past experiences) and episodic simulation (i.e., imagining specific future experiences) are associated with enhanced activity in a common set of neural regions, often referred to as the core network. This network comprises the hippocampus, parahippocampal cortex, lateral and medial parietal cortex, lateral temporal cortex, and medial prefrontal cortex. Evidence for a core network has been taken as support for the idea that episodic memory and episodic simulation are supported by common processes. Much remains to be learned about how specific core network regions contribute to specific aspects of episodic simulation. Prior neuroimaging studies of episodic memory indicate that certain regions within the core network are differentially sensitive to the amount of information recollected (e.g., the left lateral parietal cortex). In addition, certain core network regions dissociate as a function of their timecourse of engagement during episodic memory (e.g., transient activity in the posterior hippocampus and sustained activity in the left lateral parietal cortex). In the current study, we assessed whether similar dissociations could be observed during episodic simulation. We found that the left lateral parietal cortex modulates as a function of the amount of simulated details. Of particular interest, while the hippocampus was insensitive to the amount of simulated details, we observed a temporal dissociation within the hippocampus: transient activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. Because the posterior hippocampal and lateral parietal findings parallel those observed previously during episodic memory, the present results add to the evidence that episodic memory and episodic simulation are supported by common processes. Critically, the present study also provides evidence that regions within the core network support dissociable processes.

Findings reported in the memory literature suggest that the emotional components of an encoding episode can be dissociated from nonemotional memory. In particular, it has been found that the previous association with threatening events can be retrieved in aversive conditioning even in the absence of item identification. In the present study, we test whether emotional source memory can be independent of item recognition. Participants saw pictures of snakes paired with threatening and nonthreatening context information (poisonousness or nonpoisonousness). In the source memory test, participants were required to remember whether a snake was associated with poisonousness or nonpoisonousness. A simple extension of a well-established multinomial source monitoring model was used to measure source memory for unrecognized items. By using this model, it was possible to assess directly whether participants were able to associate a previously seen snake with poisonousness or nonpoisonousness even if the snake itself was not recognized as having been presented during the experiment. In 3 experiments, emotional source memory was only found for recognized items. While source memory for recognized items differed between emotional and nonemotional information, source memory for unrecognized items was equally absent for emotional and nonemotional information. We conclude that emotional context information is bound to item representations and cannot be retrieved in the absence of item recognition. (PsycINFO Database Record

Episodic memory formation depends on information about a stimulus being integrated within a precise spatial and temporal context, a process dependent on the hippocampus and prefrontal cortex. Investigations of putative functional interactions between these regions are complicated by multiple direct and indirect hippocampal-prefrontal connections. Here application of a pharmaco-genetic deactivation technique enabled an investigation of the mnemonic contributions of two direct hippocampal-medial prefrontal cortex (mPFC) pathways; one arising in the dorsal CA1 (dCA1), the other in the intermediate CA1 (iCA1). While, deactivation of either pathway impaired episodic memory, the resulting pattern of mnemonic deficits was significantly different; deactivation of the dCA1→mPFC pathway selecƟvely disrupted temporal order judgements, while iCA1→mPFC pathway deactivation disrupted spatial memory. These findings reveal a major, previously unsuspected division of function among A1 neurons that project directly to the mPFC. Such sub-networks may enable the distinctiveness of contextual information to be maintained within an episodic memory circuit.

This study aimed at investigating the ability to learn regularities across the life span and examine whether this learning process can be supported or hampered by verbalizations. For this purpose, children (aged 8-10 years) and younger (aged 19-30 years) and older (aged 70-80 years) adults took part in a sequence learning experiment. We found that verbalizing sequence-congruent information during learning is a powerful tool to generate explicit knowledge and it is especially helpful for younger adults. Although recent research suggests that implicit learning can be influenced by directing the participants' attention to relevant aspects of the task, verbalizations had a much weaker influence on implicit than explicit learning. Our results show that verbalizing during learning slows down reaction times (RTs) but does not influence the amount of implicit learning. Especially older adults were not able to overcome the cost of the dual-task situation. Younger adults, in contrast, show an initial dual-tasking cost that, in the case of a helpful verbalization, is overcome with practice and turns into a RT and learning benefit. However, when the verbalization is omitted this benefit is lost, that is, better implicit learning seems to be confined to situations in which the supporting verbalization is maintained. Additionally, we did not find reliable age differences in implicit learning in the no verbalization groups, which speaks in favor of age-invariant models of implicit learning across the life span. (PsycINFO Database Record

Hemorrhagic stroke has many symptoms, including central pain, learning and memory impairments, motor deficits, language problems, emotional disturbances, and social maladjustment. Lesions of the ventral basal complex (VBC) of the thalamus elicit thermal and mechanical hyperalgesia, forming an animal model of central post-stroke pain (CPSP). However, no research has yet examined the involvement of learning and memory in CPSP using an animal model. The present study examined whether VBC lesions affect motor function, conditioned place preference (CPP; implicit memory), and spatial learning (explicit memory) in the acquisition and retrieval phases. The results showed that rats with VBC lesions exhibited thermal hyperalgesia in the acquisition and retrieval phases, indicating that these lesions can induce CPSP. During these phases, the rats with VBC lesions exhibited enhanced (morphine-induced) CPP learning. These lesions did not affect the rats' total distance travelled, time spent, or velocity in the spatial learning tasks. The lesions also did not affect motor function in the rotarod task. Altogether, VBC lesions resulted in CPSP and facilitated CPP (implicit memory). However, the lesions did not affect spatial learning (explicit memory) or motor function. The relationship between CPSP and learning and memory is important for patients who suffer from such central pain. The implications of the present study may provide insights into helping reduce CPSP and its associated symptoms.

The precise role of the prefrontal and posterior parietal cortices in recognition performance remains controversial, with questions about whether these regions contribute to recognition via the availability of mnemonic evidence or via decision biases and retrieval orientation. Here we used an explicit memory cueing paradigm, whereby external cues probabilistically predict upcoming memoranda as old or new, in our case with 75% validity, and these cues affect recognition decision biases in the direction of the cue. The present study applied bilateral transcranial direct current stimulation (tDCS) over prefrontal or posterior parietal cortex, or sham tDCS, to test the causal role of these regions in recognition accuracy or decision biasing. Participants who received tDCS over prefrontal cortex showed increased cue utilization compared to tDCS over posterior parietal cortex and sham tDCS, suggesting that the prefrontal cortex is involved in processes that contribute to decision biases in memory.