Memorial familiarity remains intact for pictures but not for words in patients with amnestic mild cognitive impairment

Forgetting rate for the familiarity and recollection components of recognition in amnestic mild cognitive impairment: A longitudinal study

Here we aimed to investigate the rate of forgetting of the familiarity and recollection components of recognition in patients at the onset of medial temporal lobe (MTL) pathology and destined to convert to Alzheimer's disease (AD). For this purpose, we conducted a longitudinal study of 13 patients who were diagnosed with amnestic mild cognitive impairment (a-MCI) at the first assessment and followed-up for 3 years. During this time, five patients converted to AD and eight remained in a stable condition of cognitive impairment. A group of 15 healthy subjects were enrolled as the control group (HC). In order to separately quantify the contribution of recollection and familiarity to recognition memory performance, the experimental sample was submitted to a modified version of Huppert and Piercy's procedure that included a Remember/Know paradigm. Data demonstrated that both stable and converter a-MCI patients forgot memory traces relative to the familiarity components of recognition at the same rate as HC. Conversely, converter a-MCI patients showed accelerated long-term forgetting specifically for the recollection component of recognition compared to stable a-MCI and HC. This is the first empirical demonstration that familiarity and recollection components of declarative memory are subject to different rates of forgetting in a-MCI patients as a function of their longitudinal clinical outcome. Our finding of accelerated long-term forgetting of the recollection component of recognition disclosed by converter a-MCI patients suggests that atrophy in the MTL not only interferes with the storage aspects but also disrupts the consolidation of memory traces.

Drawing promotes memory retention in a patient with sleep-related anterograde amnesia

Drawing is a powerful tool to enhance memory in healthy participants and patients with probable dementia. Here, we investigated whether the drawing effect could extend to patient CT, a young woman with severe anterograde amnesia. Following surgery for a midline tumor involving her septum pellucidium and extending down into her fornices bilaterally, CT experienced a severe case of sleep-related amnesia. She can remember information encountered throughout the day, but when waking up in the morning or following a nap she forgets information learned prior to sleep. Here, we tested CT and 21 age-matched controls in a 3-day within-subjects design, during which participants encoded words by either drawing or writing them down. Memory for encoded words was tested in two conditions that each followed a 12-h delay, once after a night of sleep, and once after 12 h of wake. Despite her severe memory impairment, CT showed a drawing effect that was comparable to controls in both sleep and wake conditions. Whereas CT's memory for written words was consistently impaired relative to controls, her memory for drawn words was at the lower control range following a waking delay and above chance following a sleep delay. We suggest that amnesic patients may benefit from the drawing effect due to the recruitment of brain regions outside of the hippocampal system for encoding and consolidation. Furthermore, in control participants, sleep benefited memory for written words, but not for drawn words, suggesting that sleep preferentially consolidates memories that are more dependent on the hippocampal system.

Revisiting Snodgrass and Vanderwart in photograph form: The Keele Photo Stimulus Set (KPSS)

Over the last 40 years, object recognition studies have moved from using simple line drawings, to more detailed illustrations, to more ecologically valid photographic representations. Researchers now have access to various stimuli sets, however, existing sets lack the ability to independently manipulate item format, as the concepts depicted are unique to the set they derive from. To enable such comparisons, Rossion and Pourtois (2004) revisited Snodgrass and Vanderwart's (1980) line drawings and digitally re-drew the objects, adding texture and shading. In the current study, we took this further and created a set of stimuli that showcase the same objects in photographic form. We selected six photographs of each object (three color/three grayscale) and collected normative data and RTs. Naming accuracy and agreement was high for all photographs and appeared to steadily increase with format distinctiveness. In contrast to previous data patterns for drawings, naming agreement (H values) did not differ between grey and color photographs, nor did familiarity ratings. However, grey photographs received significantly lower mental imagery agreement and visual complexity scores than color photographs. This suggests that, in comparison to drawings, the ecological nature of photographs may facilitate deeper critical evaluation of whether they offer a good match to a mental representation. Color may therefore play a more vital role in photographs than in drawings, aiding participants in judging the match with their mental representation. This new photographic stimulus set and corresponding normative data provide valuable materials for a wide range of experimental studies of object recognition.

Icono: a universal language that shows what it says

This article lays out the foundation of a new language for easier written communication that is inherently reader-friendly and inherently international. Words usually consist of strings of sounds or squiggles whose meanings are merely a convention. In Icono, instead, they typically are strings of icons that illustrate what they stand for. "Train," for example, is expressed with the icon of a train, "future" with the icon of a clock surrounded by a clockwise arrow, and "mammal" with the icons of a cow and a mouse-their combination's meaning given by what they have in common. Moreover, Icono reveals sentence structure graphically before, rather than linguistically after, one begins reading. On smartphones and computers, writing icons can now be faster than writing alphabetic words. And using simple pictures as words helps those who struggle with conditions like dyslexia, aphasia, cerebral palsy, and autism with speech impairment. Because learning its pronunciation or phonetic spelling is optional rather than a prerequisite, and because it shows what it says, Icono is bound to be easier to learn to read-and then easier to read-than any other language, including our own.

Semantic-based memory-encoding strategy and cognitive stimulation in enhancing cognitive function and daily task performance for older adults with mild cognitive impairment: A pilot non-randomised cluster controlled trial

AIM

To investigate the effectiveness of a semantic-based memory-encoding strategy intervention and cognitive stimulation that enhances function for older adults with mild cognitive impairment.

METHODS

A two-armed single-blind non-randomised cluster controlled trial was conducted. Participants in two centres were allocated to the semantic-based memory-encoding experimental group and those in the other two centres received cognitive stimulation. In both groups, one centre- or community-based session and one home-based session were provided weekly for 10 weeks. Outcome measures included attention, memory and general cognitive function (Word List Memory and Word List Recall of the Consortium to Establish a Registry for the Alzheimer's disease, Digit Span Forwards and Backwards and the Cognistat), and daily task performance (Disability Assessment for Dementia and Lawton Instrumental Activities of Daily Living Scale). They were administered pre- and post-intervention.

RESULTS

Thirty-nine participants completed the study. No significant differences were revealed in the demographic or baseline data. The experimental group showed significant improvements in daily task performance (Disability Assessment for Dementia; p = 0.003), memory outcomes (Word List Recall; p < 0.001), general cognitive function (Cognistat subtests of Memory and Similarity; ps = 0.002 and < 0.001). The cognitive stimulation control group did not show any significant improvement in the measures. Between-group analysis showed significant differences in favour of the experimental group for the outcome measures of the Word List Recall and Cognistat Similarity subtest (ps < 0.001).

CONCLUSIONS

This study shows that the semantic-based memory-encoding strategy is more superior than cognitive stimulation with improvements in attention, memory, general cognitive function and daily task performance for people with a mild cognitive impairment.

TRIAL REGISTRATION

ClinicalTrials.gov Protocol Registration and Results System (NCT02953964).

Familiarity Deficits for Words and Objects in Amnestic Mild Cognitive Impairment in a Context Minimizing the Role of Recollection

OBJECTIVES

Amnestic mild cognitive impairment (aMCI) is associated with cortical thinning in perirhinal and entorhinal cortices, key regions of the brain supporting familiarity. Individuals with aMCI demonstrate familiarity deficits in their behavior, often repeating questions in the same conversation. While familiarity deficits in healthy aging are minimal, past studies measuring familiarity in aMCI have mixed results, perhaps due to the influence of recollection. We therefore used a paradigm that minimized the influence of recollection, and hypothesized that familiarity would be impaired in aMCI relative to age-matched controls, but not in healthy older adults relative to younger adults. We also hypothesized that familiarity deficits in aMCI would be greater for objects than words because the perirhinal cortex plays a significant role in visual discrimination.

METHODS

A sample of 36 younger adults, 38 cognitively intact older adults, and 30 older adults with aMCI made absolute frequency judgments for words and objects seen a variable number of times in an incidental encoding task. Estimates of familiarity were derived from correlating participants' frequency judgments with the actual frequency of presentation.

RESULTS

Familiarity was largely spared in healthy aging, with minor deficits in familiarity for words. Familiarity deficits were evident in aMCI comparably for words and objects.

DISCUSSION

The present research underscores the need to study familiarity in contexts minimizing recollection, particularly when comparing groups with different levels of recollection, and adds to our understanding of the phenomenology of aMCI. Familiarity deficits may provide an early biomarker of dementia risk.

Boosting Familiarity-Based Memory Decisions in Alzheimer's Disease: The Importance of Metacognition

OBJECTIVE

Recent studies in Alzheimer's disease (AD) have suggested that AD patients are not always able to rely on their feeling of familiarity to improve their memory decisions to the same extent as healthy participants. This underuse of familiarity in AD could result from a learned reinterpretation of fluency as a poor cue for memory that would prevent them to attribute a feeling of fluency to a previous encounter. The primary goal of this study was to determine whether AD patients could relearn the association between processing fluency and past exposure after being repeatedly exposed to situations where using this association improves the accuracy of their memory decisions.

METHOD

Thirty-nine patients with probable AD were recruited and asked to complete several recognition tests. During these tests, participants were put either in a condition where the positive contingency between fluent processing and previous encounters with an item was systematically confirmed (intervention condition) or in a condition where there was no correlation between fluency and prior exposure (control condition). The efficacy of the intervention was evaluated at three time points (baseline, posttest, and 3-month follow-up).

RESULTS

Our results indicated that all AD patients do not benefit to the same extent from the training. Two variables appeared to influence the likelihood that participants increase and maintain their reliance on the fluency cues after the intervention: the ability to detect the fluency manipulation and the preservation of implicit metacognitive skills.

CONCLUSION

These findings indicate the importance of metacognition for inferential attribution processes in memory.

Deficits in recent but not lifetime familiarity in amnestic mild cognitive impairment

People with amnestic mild cognitive impairment (aMCI) repeat questions, seemingly without any sense of familiarity (i.e., recognition of prior occurrence without recollection of episodic context). Accumulation of neurofibrillary tau in preclinical Alzheimer's disease begins in perirhinal cortex, a medial temporal lobe region linked to familiarity. Both observations would predict impaired familiarity assessment in aMCI; however, the extant evidence is mixed. To reveal familiarity impairments, it may be necessary to minimize the influence of recollection. In the current study, older adults with aMCI and healthy controls were administered two tasks on which a well-characterized patient (NB) with selective familiarity impairments due to surgical left temporal lobe excision sparing the hippocampus showed abnormal performance: frequency judgments for words exposed to in a recent study phase and judgments of cumulative lifetime familiarity for object concepts denoted by words. We also administered a process dissociation procedure (PDP) task that previously revealed spared familiarity in aMCI. We predicted that familiarity would be spared in aMCI on the PDP task, but impaired when assessed by frequency judgments for recent laboratory exposures and lifetime familiarity judgments. Familiarity was spared on the PDP task, but was impaired when probed with frequency judgments for recently exposed words in aMCI. Lifetime familiarity was also not impaired in aMCI. These results highlight the benefits of studying familiarity under conditions that minimize recollection and the value of frequency judgments in revealing familiarity deficits, and suggest that perirhinal cortex may not be necessary for accessing familiarity accumulated over a lifetime of experience.

Drawing pictures at encoding enhances memory in healthy older adults and in individuals with probable dementia

We explored the efficacy of drawing pictures as an encoding strategy to enhance memory performance in healthy older adults and individuals with probable dementia. In an incidental encoding phase, participants were asked to either draw a picture or write out each word from a set of 30 common nouns for 40 seconds each. Episodic memory for the target words was compared in a group of healthy older adults to individuals with probable dementia (MMSE/MOCA range 4 to 25). In two experiments we showed that recall and recognition performance was higher for words that were drawn than written out during encoding, for both participant groups. We suggest that incorporating visuo-perceptual information into memory enhanced performance by increasing reliance on visual-sensory brain regions, which are relatively intact in these populations. Our findings demonstrate that drawing is a valuable technique leading to measurable gains in memory performance for individuals with probable dementia.

Explicit and implicit memory for music in healthy older adults and patients with mild Alzheimer's disease

Introduction: Previous studies have found that music paired with lyrics at encoding may improve the memory performance of patients with mild Alzheimer's disease (AD). To further explore memory for different types of musical stimuli, the current study examined both implicit and explicit memory for music with and without lyrics compared to spoken lyrics. Method: In this mixed design, patients with probable mild AD (n = 15) and healthy older adults (n = 13) listened to auditory clips (song, instrumental, or spoken lyrics varied across three sessions) and then had their memory tested. Implicit memory was measured by the mere exposure effect. Explicit recognition memory was measured using a confidence-judgment receiver operating characteristic (ROC) paradigm, which allowed examination of the separate contributions made by familiarity and recollection. Results: A significant implicit memory mere exposure effect was found for both groups in the instrumental and song but not the spoken condition. Both groups had the best explicit memory performance in the spoken condition, followed by song, and then instrumental conditions. Healthy older adults demonstrated more recollection than patients with AD in the song and spoken conditions, but both groups performed similarly in the instrumental condition. Patients with AD demonstrated more familiarity in the instrumental and song conditions than in the spoken condition. Conclusions: The results have implications for memory interventions for patients with mild AD. The implicit memory findings suggest that patients with AD may still show a preference for information familiar to them. The explicit memory results support prior findings that patients with AD rely heavily on familiarity, but also suggest that there may be limitations on the benefits that music can provide to recognition memory performance.

Response bias and response monitoring: Evidence from healthy older adults and patients with mild Alzheimer's disease

Patients with Alzheimer's disease (AD) often exhibit an abnormally liberal response bias in recognition memory tests, responding "old" more frequently than "new." Investigations have shown patients can to shift to a more conservative response bias when given instructions. We examined if patients with mild AD could alter their response patterns when the ratio of old items is manipulated without explicit instruction. Healthy older adults and AD patients studied lists of words and then were tested in three old/new ratio conditions (30%, 50%, or 70% old items). A subset of participants provided estimates of how many old and new items they saw in the memory test. We demonstrated that both groups were able to change their response patterns without the aid of explicit instructions. Importantly, AD patients were more likely to estimate seeing greater numbers of old than new items, whereas the reverse was observed for older adults. Elevated estimates of old items in AD patients suggest their liberal response bias may be attributed to their reliance on familiarity. We conclude that the liberal response bias observed in AD patients is attributable to their believing that more of the test items are old and not due to impaired meta-memorial monitoring abilities.

A short cut to the past: Cueing via concrete objects improves autobiographical memory retrieval in Alzheimer's disease patients

Older adults diagnosed with Alzheimer's disease (AD) have difficulties accessing autobiographical memories. However, this deficit tends to spare memories dated to earlier parts of their lives, and may partially reflect retrieval deficits rather than complete memory loss. Introducing a novel paradigm, the present study examines whether autobiographical memory recall can be improved in AD by manipulating the sensory richness, concreteness and cultural dating of the memory cues. Specifically, we examine whether concrete everyday objects historically dated to the participants' youth (e.g., a skipping rope), relative to verbal cues (i.e., the verbal signifiers for the objects) facilitate access to autobiographical memories. The study includes 49 AD patients, and 50 healthy, older matched control participants, all tested on word versus object-cued recall. Both groups recalled significantly more memories, when cued by objects relative to words, but the advantage was significantly larger in the AD group. In both groups, memory descriptions were longer and significantly more episodic in nature in response to object-cued recall. Together these findings suggest that the multimodal nature of the object cues (i.e. vision, olfaction, audition, somatic sensation) along with specific cue characteristics, such as time reference, texture, shape, may constrain the retrieval search, potentially minimizing executive function demands, and hence strategic processing requirements, thus easing access to autobiographical memories in AD.

Recollection and familiarity in aging individuals: Gaining insight into relationships with medial temporal lobe structural integrity

Dual-process theories posit that two separate processes are involved in recognition, namely recollection and familiarity. Studies investigating the neuroanatomical substrates of these two processes have frequently revealed that, while recollection is functionally linked with the hippocampus, familiarity appears to be associated with perirhinal and/or entorhinal cortices integrity. Interestingly these regions are known to be sensitive to normal and neuropathological aging processes. The objective of this study was to examine the effects of aging on recollection and familiarity performance, as well as to investigate associations with the rate of false alarms. In older individuals, we further aimed to explore relationships between these recognition variables and structural integrity of the hippocampus and the entorhinal and perirhinal cortices. Younger (N = 56) and older (N = 59) adults were tested on a computerized recollection and familiarity task. In a separate session, older adults (N = 56) underwent a structural MRI. Hippocampal, entorhinal and perihinal cortices volumes were automatically segmented and then manually corrected to ensure validity of the volumetric assessment. Regional volumes were normalized for total intracranial volume. While the overall recognition performance did not significantly differ across groups, our results reveal a decrease in recollection, together with an increase in familiarity in older adults. The increase reliance on familiarity was significantly and positively associated with the rate of false alarms. In the older adult sample, significant positive associations were found between recollection estimates and normalized hippocampal volumes. The normalized total hippocampal volume accounted for 25% of the variance in recollection performance. No correlation was found between any recognition variables and perirhinal or entorhinal cortices volumes. Overall, our results suggest that the age-related impairment in recollection is linked with reduced hippocampal structural integrity.

Development of a tool to facilitate real life activity retraining in hand and arm therapy

Introduction

Successful recovery of upper extremity function after stroke is more likely when the affected limb is used regularly in daily life. We developed an iPad (Apple) application called the ‘Aid for Decision-Making in Occupation Choice for Hand’ to facilitate daily upper extremity use. This study examined the suitability of items and pictures in the Aid for Decision-Making in Occupation Choice for Hand, and tested a paper prototype of the application (which has since been produced).

Method

We used a Delphi method with 10 expert occupational therapists to refine the items in the aid. Next, we prepared pictures of items in the aid and confirmed their suitability by testing them with 10 patients (seven stroke, three cervical spondylotic myelopathy). Nine occupational therapists conducted field tests with a paper prototype of the aid in clinical practice to examine its utility.

Results

After four Delphi rounds, we selected 130 items representing activities of daily living, organized into 16 categories. Of 130 pictures, 128 were recognizable to patients as representing the intended activities. Based on testing of the paper prototype, we found the Aid for Decision-Making in Occupation Choice for Hand process was suitable for clinical practice, and could be organized into six steps.

Conclusion

The Aid for Decision-Making in Occupation Choice for Hand process may promote daily upper extremity use. This application, since developed, now needs to be clinically tested in its digital form.

The use of metacognitive strategies to decrease false memories in source monitoring in patients with mild cognitive impairment

Patients with amnestic mild cognitive impairment (MCI) and Alzheimer's disease (AD) often demonstrate high rates of false memories, leading to stressful and frustrating situations for both patients and caregivers in everyday life. Sometimes these false memories are due to failures in monitoring the source of the information. In the current study, we examined interventions aimed to enhance the use of the metacognitive "recall-to-reject" memory strategy. Such interventions could improve source memory and decrease false memory in patients with MCI. Because the picture superiority effect (better memory for pictures compared to words) has been shown to be present in both patients with MCI and healthy older controls, we investigated whether pictures could help patients with MCI use a recall-to-reject strategy in a simulation of real-world source memory task. In this experiment, patients with MCI and healthy older adults were asked to simulate preparing for and then taking a trip to the market. Subjects first studied 30 pictures of items in their "cupboard," followed by a list of 30 words of items on their "shopping list." At test, participants saw 90 pictures (30 cupboard, 30 list, 30 new) organized as they would be if walking down the market aisles, and are provided with either standard or metacognitive instructions. With standard instructions, they were asked if they needed to buy the item. With the metacognitive instructions, they were asked a series of questions to help guide them through a recall-to-reject strategy to highlight the different sources of memories. Results showed that the metacognitive instructions did significantly reduce the false memory rates for patients with MCI. Further studies need to investigate how to best implement these practical strategies into the everyday lives of patients.

Preserved conceptual implicit memory for pictures in patients with Alzheimer's disease

The current study examined different aspects of conceptual implicit memory in patients with mild Alzheimer's disease (AD). Specifically, we were interested in whether priming of distinctive conceptual features versus general semantic information related to pictures and words would differ for the mild AD patients and healthy older adults. In this study, 14 healthy older adults and 15 patients with mild AD studied both pictures and words followed by an implicit test section, where they were asked about distinctive conceptual or general semantic information related to the items they had previously studied (or novel items). Healthy older adults and patients with mild AD showed both conceptual priming and the picture superiority effect, but the AD patients only showed these effects for the questions focused on the distinctive conceptual information. We found that patients with mild AD showed intact conceptual picture priming in a task that required generating a response (answer) from a cue (question) for cues that focused on distinctive conceptual information. This experiment has helped improve our understanding of both the picture superiority effect and conceptual implicit memory in patients with mild AD in that these findings support the notion that conceptual implicit memory might potentially help to drive familiarity-based recognition in the face of impaired recollection in patients with mild AD.

Selective familiarity deficits in otherwise cognitively intact aging individuals with genetic risk for Alzheimer's disease

Introduction

Familiarity has been associated with integrity of the rhinal cortex. Thus, impairment in familiarity is expected in very early stages of Alzheimer's disease (AD). The apolipoprotein E (APOE) ε4 allele is a major risk factor for AD. Here, we investigated the effect of the APOE ε4 status on familiarity in cognitively normal aging individuals.

Methods

Eighty-one individuals aged between 55 and 80 years, 21 carriers and 60 noncarriers, were used in these analyses. A cognitive evaluation was performed on all participants to document the absence of objective cognitive deficits. The effect of APOE ε4 status on familiarity was tested using independent sample t test and an analysis of covariance controlling for age, gender, and education.

Results

The groups did not differ in term of age, education, and male/female ratio. APOE ε4 carriers showed a significant reduction in familiarity. No other cognitive deficit was observed in the group of ε4 carriers, relative to noncarriers.

Discussion

APOE ε4 is associated with a reduction in familiarity in the absence of other cognitive deficits. These results suggest that performance in familiarity could represent an early cognitive marker for individuals at risk of AD.

The effects of healthy aging, amnestic mild cognitive impairment, and Alzheimer's disease on recollection and familiarity: a meta-analytic review

It is well established that healthy aging, amnestic Mild Cognitive Impairment (aMCI), and Alzheimer's Disease (AD) are associated with substantial declines in episodic memory. However, there is still debate as to how two forms of episodic memory - recollection and familiarity - are affected by healthy and pathological aging. To address this issue we conducted a meta-analytic review of the effect sizes reported in studies using remember/know (RK), receiver operating characteristic (ROC) and process dissociation (PD) methods to examine recollection and familiarity in healthy aging (25 published reports), aMCI (9 published reports), and AD (5 published reports). The results from the meta-analysis revealed that healthy aging is associated with moderate-to-large recollection impairments. Familiarity was not impaired in studies using ROC or PD methods but was impaired in studies that used the RK procedure. aMCI was associated with large decreases in recollection whereas familiarity only tended to show a decrease in studies with a patient sample comprised of both single-domain and multiple-domain aMCI patients. Lastly, AD was associated with large decreases in both recollection and familiarity. The results are consistent with neuroimaging evidence suggesting that the hippocampus is critical for recollection whereas familiarity is dependent on the integrity of the surrounding perirhinal cortex. Moreover, the results highlight the relevance of method selection when examining aging, and suggest that familiarity deficits might be a useful behavioral marker for identifying individuals that will develop dementia.

Associative memory and its cerebral correlates in Alzheimer׳s disease: evidence for distinct deficits of relational and conjunctive memory

This study investigated the impact of Alzheimer׳s disease (AD) on conjunctive and relational binding in episodic memory. Mild AD patients and controls had to remember item-color associations by imagining color either as a contextual association (relational memory) or as a feature of the item to be encoded (conjunctive memory). Patients׳ performance in each condition was correlated with cerebral metabolism measured by FDG-PET. The results showed that AD patients had an impaired capacity to remember item-color associations, with deficits in both relational and conjunctive memory. However, performance in the two kinds of associative memory varied independently across patients. Partial Least Square analyses revealed that poor conjunctive memory was related to hypometabolism in an anterior temporal-posterior fusiform brain network, whereas relational memory correlated with metabolism in regions of the default mode network. These findings support the hypothesis of distinct neural systems specialized in different types of associative memory and point to heterogeneous profiles of memory alteration in Alzheimer׳s disease as a function of damage to the respective neural networks.

Individual differences in forced-choice recognition memory: partitioning contributions of recollection and familiarity

In forced-choice recognition memory, two different testing formats are possible under conditions of high target-foil similarity: Each target can be presented alongside foils similar to itself (forced-choice corresponding; FCC), or alongside foils similar to other targets (forced-choice noncorresponding; FCNC). Recent behavioural and neuropsychological studies suggest that FCC performance can be supported by familiarity whereas FCNC performance is supported primarily by recollection. In this paper, we corroborate this finding from an individual differences perspective. A group of older adults were given a test of FCC and FCNC recognition for object pictures, as well as standardized tests of recall, recognition, and IQ. Recall measures were found to predict FCNC, but not FCC performance, consistent with a critical role for recollection in FCNC only. After the common influence of recall was removed, standardized tests of recognition predicted FCC, but not FCNC performance. This is consistent with a contribution of only familiarity in FCC. Simulations show that a two-process model, where familiarity and recollection make separate contributions to recognition, is 10 times more likely to give these results than a single-process model. This evidence highlights the importance of recognition memory test design when examining the involvement of recollection and familiarity.

Recognition memory in amnestic-mild cognitive impairment: insights from event-related potentials

Episodic memory loss is the hallmark cognitive dysfunction associated with Alzheimer’s disease (AD). Amnestic mild cognitive impairment (a-MCI) frequently represents a transitional stage between normal aging and early AD. A better understanding of the qualitative features of memory loss in a-MCI may have important implications for predicting those most likely to harbor AD-related pathology and for disease monitoring. Dual process models of memory argue that recognition memory is subserved by the dissociable processes of recollection and familiarity. Work studying recognition memory in a-MCI from this perspective has been controversial, particularly with regard to the integrity of familiarity. Event-related potentials (ERPs) offer an alternative means for assessing these functions without the associated assumptions of behavioral estimation methods. ERPs were recorded while a-MCI patients and cognitively normal (CN) age-matched adults performed a recognition memory task. When retrieval success was measured (hits versus correct rejections) in which performance was matched by group, a-MCI patients displayed similar neural correlates to that of the CN group, including modulation of the FN400 and the late positive complex (LPC) which are thought to index familiarity and recollection, respectively. Alternatively, when the integrity of these components was measured based on retrieval attempts (studied versus unstudied items), a-MCI patients displayed a reduced FN400 and LPC. Furthermore, modulation of the FN400 correlated with a behavioral estimate of familiarity and the LPC with a behavioral estimate of recollection obtained in a separate experiment in the same individuals, consistent with the proposed mappings of these indices. These results support a global decline of recognition memory in a-MCI, which suggests that the memory loss of prodromal AD may be qualitatively distinct from normal aging.

A biased competition account of attention and memory in Alzheimer's disease

The common view of Alzheimer's disease (AD) is that of an age-related memory disorder, i.e. declarative memory deficits are the first signs of the disease and associated with progressive brain changes in the medial temporal lobes and the default mode network. However, two findings challenge this view. First, new model-based tools of attention research have revealed that impaired selective attention accompanies memory deficits from early pre-dementia AD stages on. Second, very early distributed lesions of lateral parietal networks may cause these attention deficits by disrupting brain mechanisms underlying attentional biased competition. We suggest that memory and attention impairments might indicate disturbances of a common underlying neurocognitive mechanism. We propose a unifying account of impaired neural interactions within and across brain networks involved in attention and memory inspired by the biased competition principle. We specify this account at two levels of analysis: at the computational level, the selective competition of representations during both perception and memory is biased by AD-induced lesions; at the large-scale brain level, integration within and across intrinsic brain networks, which overlap in parietal and temporal lobes, is disrupted. This account integrates a large amount of previously unrelated findings of changed behaviour and brain networks and favours a brain mechanism-centred view on AD.

Ecological assessment of mild cognitive impairment and Alzheimer disease using the Rivermead Behavioural Memory Test

INTRODUCTION

The Rivermead Behavioural Memory Test (RBMT) is a short, ecologically-valid memory test battery that can provide data about a subject's memory function in daily life. We used RBMT to examine daily memory function in patients with mild cognitive impairment (MCI), Alzheimer disease (AD), and in healthy controls. We also evaluated differences between the memory profiles of subjects whose MCI remained stable after 1 year and those with conversion to AD.

PATIENTS AND METHODS

Sample of 91 subjects older than 60 years: 30 controls, 27 MCI subjects and 34 AD patients. Subjects were assessed using MMSE and RBMT.

RESULTS

The 40 men and 51 women in the sample had a mean age of 74.29±6.71 and 5.87±2.93 years of education. For the total profile and screening RBMT scores (P<.001) and total MMSE scores (P<.05), control subjects scored significantly higher than those with MCI, who in turn scored higher than AD patients. In all subtests, the control group (P<.001) and MCI group (P<.05) were distinguishable from the AD group. Prospective, retrospective, and orientation subtests found differences between the MCI and control groups (P<.05). MCI subjects who progressed to AD scored lower at baseline on the total RBMT and MMSE, and on name recall, belongings, story-immediate recall, route-delayed recall, orientation (P<.05), face recognition, story-delayed recall, and messages-delayed recall sections (P<.01).

CONCLUSIONS

RBMT is an ecologically-valid episodic memory test that can be used to differentiate between controls, MCI subjects, and AD subjects. It can also be used to detect patients with MCI who will experience progression to AD.

Response to Algarabel et al., 2012 "Recognition memory deficits in mild cognitive impairment". Reconsidering claims of familiarity disruptions in mild cognitive impairment

There is some debate over the relative impairment of recollection and familiarity in mild cognitive impairment (MCI). A recent publication by Algarabel et al. (2012, Recognition memory deficits in mild cognitive impairment, Aging, Neuropsychology, and Cognition, 19, 608-619) claims to undermine previous studies reporting preserved familiarity in patients with MCI. Here, we respond to their main criticisms, concluding that they are not sufficiently supported by the data presented. The role of recollection and familiarity in MCI remains unresolved and further work will be required to disentangle the mixed literature.

Pattern separation and pattern completion in Alzheimer's disease: evidence of rapid forgetting in amnestic mild cognitive impairment

Over the past four decades, the characterization of memory loss associated with Alzheimer's disease (AD) has been extensively debated. Recent iterations have focused on disordered encoding versus rapid forgetting. To address this issue, we used a behavioral pattern separation task to assess the ability of the hippocampus to create and maintain distinct and orthogonalized visual memory representations in patients with amnestic mild cognitive impairment (aMCI) and mild AD. We specifically used a lag-based continuous recognition paradigm to determine whether patients with aMCI and mild AD fail to encode visual memory representations or whether these patients properly encode representations that are rapidly forgotten. Consistent with the rapid forgetting hypothesis of AD, we found that patients with aMCI demonstrated decreasing pattern separation rates as the lag of interfering objects increased. In contrast, patients with AD demonstrated consistently poor pattern separation rates across three increasingly longer lags. We propose a continuum that reflects underlying hippocampal neuropathology whereby patients with aMCI are able to properly encode information into memory but rapidly lose these memory representations, and patients with AD, who have extensive hippocampal and parahippocampal damage, cannot properly encode information in distinct, orthogonal representations. Our results also revealed that whereas patients with aMCI demonstrated similar behavioral pattern completion rates to healthy older adults, patients with AD showed lower pattern completion rates when we corrected for response bias. Finally, these behavioral pattern separation and pattern completion results are discussed in terms of the dual process model of recognition memory.

Manipulating letter fluency for words alters electrophysiological correlates of recognition memory

The mechanisms that give rise to familiarity memory have received intense research interest. One current topic of debate concerns the extent to which familiarity is driven by the same fluency sources that give rise to certain implicit memory phenomena. Familiarity may be tied to conceptual fluency, given that familiarity and conceptual implicit memory can exhibit similar neurocognitive properties. However, familiarity can also be driven by perceptual factors, and its neural basis under these circumstances has received less attention. Here we recorded brain potentials during recognition testing using a procedure that has previously been shown to encourage a reliance on letter information when assessing familiarity for words. Studied and unstudied words were derived either from two separate letter pools or a single letter pool ("letter-segregated" and "normal" conditions, respectively) in a within-subjects contrast. As predicted, recognition accuracy was higher in the letter-segregated relative to the normal condition. Electrophysiological analyses revealed parietal old-new effects from 500-700 ms in both conditions. In addition, a topographically dissociable occipital old-new effect from 300-700 ms was present in the letter-segregated condition only. In a second experiment, we found that similar occipital brain potentials were associated with confident false recognition of words that shared letters with studied words but were not themselves studied. These findings indicate that familiarity is a multiply determined phenomenon, and that the stimulus dimensions on which familiarity is based can moderate its neural correlates. Conceptual and perceptual contributions to familiarity vary across testing circumstances, and both must be accounted for in theories of recognition memory and its neural basis.

Using pictures and words to understand recognition memory deterioration in amnestic mild cognitive impairment and Alzheimer's disease: a review

Difficulty recognizing previously encountered stimuli is one of the earliest signs of incipient Alzheimer's disease (AD). Work over the last 10 years has focused on how patients with AD and those in the prodromal stage of amnestic mild cognitive impairment make recognition decisions for visual and verbal stimuli. Interestingly, both groups of patients demonstrate markedly better memory for pictures over words, to a degree that is significantly greater in magnitude than their healthy older counterparts. Understanding this phenomenon not only helps to conceptualize how memory breaks down in AD, but also potentially provides the basis for future interventions. This review critically examines recent recognition memory work using pictures and words in the context of the dual-process theory of recognition and current hypotheses of cognitive breakdown in the course of very early AD.

Familiarity-based memory as an early cognitive marker of preclinical and prodromal AD

There is great interest in the development of cognitive markers that differentiate "normal" age-associated cognitive change from that of Alzheimer's disease (AD) in its prodromal (i.e., mild cognitive impairment; MCI) or even preclinical stages. Dual process models posit that recognition memory is supported by the dissociable processes of recollection and familiarity. Familiarity-based memory has generally been considered to be spared during normal aging, but it remains controversial whether this type of memory is impaired in early AD. Here, we describe findings of estimates of recollection and familiarity in young adults (YA), cognitively normal older adults (CN), and patients with amnestic-MCI (a-MCI). These measures in the CN and a-MCI patients were then related to a structural imaging biomarker of AD that has previously been demonstrated to be sensitive to preclinical and prodromal AD, the Cortical Signature of AD (ADsig). Consistent with much work in the literature, recollection, but not familiarity, was impaired in CN versus YA. Replicating our prior findings, a-MCI patients displayed impairment in both familiarity and recollection. Finally, the familiarity measure was correlated with the ADsig biomarker across the CN and a-MCI group, as well as within the CN adults alone. No other standard psychometric measure was as highly associated with the ADsig, suggesting that familiarity may be a sensitive biomarker of AD-specific brain changes in preclinical and prodromal AD and that it may offer a qualitatively distinct measure of early AD memory impairment relative to normal age-associated change.

Item familiarity and controlled associative retrieval in Alzheimer's disease: an fMRI study

Typical Alzheimer's disease (AD) is characterized by an impaired form of associative memory, recollection, that includes the controlled retrieval of associations. In contrast, familiarity-based memory for individual items may sometimes be preserved in the early stages of the disease. This is the first study that directly examines whole-brain regional activity during one core aspect of the recollection function: associative controlled episodic retrieval (CER), contrasted to item familiarity in AD patients. Cerebral activity related to associative CER and item familiarity in AD patients and healthy controls (HCs) was measured with functional magnetic resonance imaging during a word-pair recognition task to which the process dissociation procedure was applied. Some patients had null CER estimates (AD-), whereas others did show some CER abilities (AD+), although significantly less than HC. In contrast, familiarity estimates were equivalent in the three groups. In AD+, as in controls, associative CER activated the inferior precuneus/posterior cingulate cortex (PCC). When performing group comparisons, no region was found to be significantly more activated during CER in HC than AD+ and vice versa. However, during associative CER, functional connectivity between this region and the hippocampus, the inferior parietal and dorsolateral prefrontal cortex (DLPFC) was significantly higher in HC than in AD+. In all three groups, item familiarity was related to activation along the intraparietal sulcus (IPS). In conclusion, whereas the preserved automatic detection of an old item (without retrieval of accurate word association) is related to parietal activation centred on the IPS, the inferior precuneus/PCC supports associative CER ability in AD patients, as in HC. However, AD patients have deficient functional connectivity during associative CER, suggesting that the residual recollection function in these patients might be impoverished by the lack of some recollection-related aspects such as autonoetic quality, episodic details and verification.