Reversible Verbal Memory Integration Deficits in Obstructive Sleep Apnoea.

When presented with novel but semantically related elements after learning verbal material, healthy participants tend to endorse these items as previously learned. This reflects the normal integration and association of novel verbal information into long-term memory. How obstructive sleep apnoea (OSA) negatively impacts verbal memory performance, and whether deficits are reversible following positive airway pressure (PAP) treatment, remain elusive. We investigated immediate and delayed OSA- and PAP treatment-related effects on verbal memory integration, using a false memory paradigm. Twenty-three patients with OSA learned lists of words semantically related to target non-presented words (1) at baseline after a polysomnography diagnosis night, (2) after a consecutive polysomnography night under PAP titration, and (3) after three months of compliant PAP treatment. At each session, participants learned 10 different lists of words, each list comprising 15 semantically related items. They had then to recognize 15 minutes later (after an intermediate vigilance task) previously learned words within a list including studied words (learned), unstudied but semantically related items (lures), and non-related unstudied items (controls). Sleep quality and fatigue questionnaires, and psychomotor vigilance tests (PVT) were administered at each session. PAP treatment led to OSA remission and improvement in objective and subjective sleep quality. Crucially, recognition of learned and lure words increased after the first night under treatment and remained stable three months later, suggesting successful memory integration and restoration of semantic processes. No treatment-related outcome was found on PVT performance. OSA exerts a detrimental but PAP-reversible effect on verbal learning and semantic memory integration mechanisms underlying the acquisition of novel memory representations.

Independent recollection/familiarity ratings can dissociate: Evidence from the effects of test context on recognition of event details.

Bodner and Richardson-Champion (2007) found a dissociative effect of test context on binary remember/know judgments about a critical set of details from a film sequence. Details of medium difficulty were more likely to be judged "recollected" when preceded by a set of difficult details than a set of easy details, but were similarly likely to be judged "familiar." Using the same paradigm, we replicated this dissociation when participants independently rated recollection and familiarity. Our finding represents the first evidence that independent recollection/familiarity ratings can be dissociated. In contrast, previous studies using independent ratings have yielded parallel effects of variables that produce dissociative effects with binary judgments. Our discussion considers potential causes of this dissociation, whether test context influenced discrimination or response bias, and implications for interpreting subjective recognition experiences. Demonstrations that test context can affect recollection reports also have implications for designing and conducting eyewitness interviews. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Hallucinations in Alzheimer's disease: failure to suppress irrelevant memories.

INTRODUCTION: Research with patients with schizophrenia suggests that inhibitory dysfunction leads to the emergence of redundant or irrelevant information from long-term memory into awareness, and that this process may be involved in generating hallucinations. We investigated whether inhibitory dysfunction in Alzheimer's disease (AD) leads to hallucinations. METHOD: AD participants and healthy matched controls were assessed with a hallucinations scale and a directed forgetting task. On the directed forgetting task, they were asked to retain a list of 10 words (i.e., List 1). Thereafter, half of the participants were asked to forget this list whereas the other half were asked to retain the list in memory. After the List 1 presentation, all participants were asked to retain another list of 10 words and, successively, were asked to remember all of the words from both lists, regardless of the previous forget or remember instruction. RESULTS: Relative to healthy matched controls, AD participants showed difficulties in suppressing the words from List 1. AD participants also showed more hallucinatory experiences than healthy matched controls. Interestingly, a significant correlation was observed between the score on the hallucinations measure and difficulties in suppressing List 1 in AD participants. DISCUSSION: Hallucinations in AD may, at least in part, be related to difficulties in suppressing memory representations, such that unwanted or repetitive thoughts intrude into consciousness.

False memory susceptibility in coma survivors with and without a near-death experience.

It has been postulated that memories of near-death experiences (NDEs) could be (at least in part) reconstructions based on experiencers' (NDErs) previous knowledge and could be built as a result of the individual's attempt to interpret the confusing experience. From the point of view of the experiencer, NDE memories are perceived as being unrivalled memories due to its associated rich phenomenology. However, the scientific literature devoted to the cognitive functioning of NDErs in general, and their memory performance in particular, is rather limited. This study examined NDErs' susceptibility to false memories using the Deese-Roediger-McDermott (DRM) paradigm. We included 20 NDErs who reported having had their experience in the context of a life-threatening event (Greyson NDE scale total score ≥7/32) and 20 volunteers (matched for age, gender, education level, and time since brain insult) who reported a life-threatening event but without a NDE. Both groups were presented with DRM lists for a recall task during which they were asked to assign "Remember/Know/Guess" judgements to any recalled response. In addition, they were later asked to complete a post-recall test designed to obtain estimates of activation and monitoring of critical lures. Results demonstrated that NDErs and volunteers were equally likely to produce false memories, but that NDErs recalled them more frequently associated with compelling illusory recollection. Of particular interest, analyses of activation and monitoring estimates suggest that NDErs and volunteers groups were equally likely to think of critical lures, but source monitoring was less successful in NDErs compared to volunteers.

Hallucinations in Healthy Older Adults: An Overview of the Literature and Perspectives for Future Research.

KEY POINTS ➢ Studies suggest a substantial minority of healthy older adults have hallucinatory experiences, in line with existing evidence on hallucinations in other age groups, though it is still unclear if hallucination prevalence increases or declines with age in older cohorts.➢ Stigma attached to both hallucinations and ageing leads to considerable under-reporting of these experiences in healthy older adults and may negatively bias how professionals, family members, and the public respond.➢ Why and when hallucinations in healthy older adults remit, persist, or progress to other clinical disorders remains poorly understood.➢ Current evidence points to a range of factors associated with hallucinations in older adults including decline in sensory or cognitive functioning, poor sleep, and psychosocial stressors (e.g., social isolation, loneliness, and bereavement), highlighting the need for accurate assessment and tailored interventions. Hallucinations, though common in youth and younger adults, are not the preserve of these age groups. Accumulating evidence shows that hallucinatory experiences are also present at surprisingly high rates in healthy older adults in the general community. Furthermore, stigma and misunderstanding of hallucinations, together with ageism, may lead to under-reporting of these experiences by older adults, and misdiagnosis or mismanagement by health and mental health practitioners. Consequently, improved public and professional knowledge is needed about the nature and significance of hallucinations with advancing age. The purpose of this review is to provide a comprehensive overview, and critical analysis, of research on the prevalence, psychosocial, and neurobiological factors associated with hallucinations in people aged 60 years and over. To the best of our knowledge, this is the first review of its kind in the literature. The evidence supports a dynamic conceptualization of hallucinations, in which the emergence of hallucinations is viewed as a balance between the sensory, cognitive, or social impairments accompanying advancing age and the degree to which compensatory processes elicited by these impairments are successful. We briefly summarize the implications of the literature for aged care services and interventions, and stress that far more studies are needed in this important field of research.

Characteristics of near-death experiences memories as compared to real and imagined events memories.

Since the dawn of time, Near-Death Experiences (NDEs) have intrigued and, nowadays, are still not fully explained. Since reports of NDEs are proposed to be imagined events, and since memories of imagined events have, on average, fewer phenomenological characteristics than real events memories, we here compared phenomenological characteristics of NDEs reports with memories of imagined and real events. We included three groups of coma survivors (8 patients with NDE as defined by the Greyson NDE scale, 6 patients without NDE but with memories of their coma, 7 patients without memories of their coma) and a group of 18 age-matched healthy volunteers. Five types of memories were assessed using Memory Characteristics Questionnaire (MCQ--Johnson et al., 1988): target memories (NDE for NDE memory group, coma memory for coma memory group, and first childhood memory for no memory and control groups), old and recent real event memories and old and recent imagined event memories. Since NDEs are known to have high emotional content, participants were requested to choose the most emotionally salient memories for both real and imagined recent and old event memories. Results showed that, in NDE memories group, NDE memories have more characteristics than memories of imagined and real events (p<0.02). NDE memories contain more self-referential and emotional information and have better clarity than memories of coma (all ps<0.02). The present study showed that NDE memories contained more characteristics than real event memories and coma memories. Thus, this suggests that they cannot be considered as imagined event memories. On the contrary, their physiological origins could lead them to be really perceived although not lived in the reality. Further work is needed to better understand this phenomenon.

Lateralized processing of false memories and pseudoneglect in aging.

Aging is associated with higher propensity to false memories and decreased retrieval of previously studied items. When young adults (YA) perform on a lateralized version of the Deese-Roediger-McDermott (DRM) paradigm, the right cerebral hemisphere (RH) is more sensitive than the left (LH) to false memories, suggesting hemispheric imbalance in the cerebral mechanisms supporting semantic and episodic memory processes. Since cerebral asymmetries tend to be reduced with age, we surmised that behavioral asymmetries in the generation of false memories would be diminished with aging. To probe this hypothesis, a lateralized version of the DRM paradigm was administered to healthy older adults (OA) and YA. During the encoding phase, lists of semantically associated words were memorized. During the retrieval session, targets (previously seen words), lures (LU) (never seen strongly semantically related words) and distracters (never seen, unrelated words) were briefly displayed either in the left or right visual fields, thus primarily stimulating the RH or LH, respectively. Participants had to decide whether the word was previously studied (Old/New), but also whether they had a strong episodic recollection (Remember) or a mere feeling of familiarity (Know) about Old words. In line with our predictions, false memories were globally higher in OA than YA, and vivid false recollections (i.e., Remember responses) were higher when LU were presented in the RH in YA, but not in OA. Additionally, we found significant correlations between YA participants' Familiarity scores and leftward attentional bias as previously evidenced using a visuospatial landmark task (Schmitz and Peigneux, 2011), an effect not present in OA. This result is in line with the hypothesis of an interplay between attentional resources allocated to visuospatial and memory processes, suggesting a memory pseudoneglect phenomenon that would be altered with aging.

Verbal overshadowing of face memory does occur in children too!

Verbal descriptions of unfamiliar faces have been found to impair later identification of these faces in adults, a phenomenon known as the "verbal overshadowing effect" (VOE). Although determining whether children are good at describing unfamiliar individuals and whether these descriptions impair their recognition performance is critical to gaining a better understanding children's eyewitness ability, only a couple of studies have examined this dual issue in children and these found no evidence of VOE. However, as there are some methodological criticisms of these studies, we decided to conduct two further experiments in 7-8, 10-11, and 13-14-year-old children and in adults using a more optimal method for the VOE to be observed. Evidence of the VOE on face identification was found in both children and adults. Moreover, neither the accuracy of descriptions, nor delay nor target presence in the lineup was found to be associated with identification accuracy. The theoretical and developmental implications of these findings are discussed.

No evidence of age-related increases in unconscious plagiarism during free recall.

In three experiments younger and older participants took part in a group generation task prior to a delayed recall task. In each, participants were required to recall the items that they had generated, avoiding plagiarism errors. All studies showed the same pattern: older adults did not plagiarise their partners any more than younger adults did. However, older adults were more likely than younger adults to intrude with entirely novel items not previously generated by anyone. These findings stand in opposition to the single previous demonstration of age-related increases in plagiarism during recall.

Does sleep promote false memories?

Memory is constructive in nature so that it may sometimes lead to the retrieval of distorted or illusory information. Sleep facilitates accurate declarative memory consolidation but might also promote such memory distortions. We examined the influence of sleep and lack of sleep on the cerebral correlates of accurate and false recollections using fMRI. After encoding lists of semantically related word associates, half of the participants were allowed to sleep, whereas the others were totally sleep deprived on the first postencoding night. During a subsequent retest fMRI session taking place 3 days later, participants made recognition memory judgments about the previously studied associates, critical theme words (which had not been previously presented during encoding), and new words unrelated to the studied items. Sleep, relative to sleep deprivation, enhanced accurate and false recollections. No significant difference was observed in brain responses to false or illusory recollection between sleep and sleep deprivation conditions. However, after sleep but not after sleep deprivation (exclusive masking), accurate and illusory recollections were both associated with responses in the hippocampus and retrosplenial cortex. The data suggest that sleep does not selectively enhance illusory memories but rather tends to promote systems-level consolidation in hippocampo-neocortical circuits of memories subsequently associated with both accurate and illusory recollections. We further observed that during encoding, hippocampal responses were selectively larger for items subsequently accurately retrieved than for material leading to illusory memories. The data indicate that the early organization of memory during encoding is a major factor influencing subsequent production of accurate or false memories.

Affective valence influences participant's susceptibility to false memories and illusory recollection.

This study examined the influence of emotional valence on the production of DRM false memories (Roediger & McDermott, 1995). Participants were presented with neutral, positive, or negative DRM lists for a later recognition (Experiment 1) or recall (Experiment 2) test. In both experiments, confidence and recollective experience (i.e., "Remember-Know" judgments; Tulving, 1985) were also assessed. Results consistently showed that, compared with neutral lists, affective lists induced more false recognition and recall of nonpresented critical lures. Moreover, although confidence ratings did not differ between the false remembering from the different kinds of lists, "Remember" responses were more often associated with negative than positive and neutral false remembering of the critical lures. In contrast, positive false remembering of the critical lures was more often associated with "Know" responses. These results are discussed in light of the Paradoxical Negative Emotion (PNE) hypothesis (Porter, Taylor, & ten Bricke, 2008).

Variations in processing resources and resistance to false memories in younger and older adults.

The influence of available processing resources on the resistance to false memories (FMs) for lists of semantically related items associated with a non-presented critical lure was examined in younger and older adults. Reducing the available resources at encoding in younger adults (Experiments 1 and 2) led to a performance similar to that of older adults (i.e., higher rates of FMs in addition to reduced rates of correct recall). However, increasing the available resources (Experiments 2 and 3) led to improvements in the rates of correct recall in both age groups and decreased the probability of FMs in younger adults, although warnings had to be added in older adults to obtain similar effects on FMs. Parallel influences on a post-recall test asking participants to report items that they had thought of but did not recall were also found. The influence of available cognitive resources for memory accuracy is also discussed with respect to activation-monitoring (e.g., McDermott & Watson, 2001) and fuzzy-trace (e.g., Brainerd & Reyna, 2002) accounts of age-related increased in false memories.

False memories: young and older adults think of semantic associates at the same rate, but young adults are more successful at source monitoring.

Two experiments explored whether the higher vulnerability to false memories in the DRM (J. Deese, 1959; H. L. Roediger & K. B. McDermott, 1995) paradigm in older compared to young adults reflects a deficit in source monitoring. In both experiments, adding together the number of falsely recalled critical lures and the number of critical lures produced on a post-recall test asking participants to report items that they had thought of but did not recall, indicated that the critical lures were activated during the experiment equally often in young and older adults. However, older adults were more likely than young adults to say that they had actually heard the lures. When strongly encouraged to examine the origin of memories (Experiment 2), the warning substantially reduced false recall in young but not older adults. These results are consistent with the idea that older adults have more difficulty later identifying the source of information that was activated as a consequence of intact semantic activation processes.