Amount, not strength of recollection, drives hippocampal activity: A problem for apparent word familiarity-related hippocampal activation.

The role of the hippocampus in recollection and familiarity remains debated. Using functional magnetic resonance imaging (fMRI), we explored whether hippocampal activity is modulated by increasing recollection confidence, increasing amount of recalled information, or both. We also investigated whether any hippocampal differences between recollection and familiarity relate to processing differences or amount of information in memory. Across two fMRI tasks, we separately compared brain responses to levels of confidence for cued word recall and word familiarity, respectively. Contrary to previous beliefs, increasing confidence/accuracy of cued recall of studied words did not increase hippocampal activity, when unconfounded by amount recollected. In contrast, additional recollection (i.e., recollecting more information than the word alone) increased hippocampal activity, although its accuracy matched that of word recall alone. Unlike cued word recall, increasing word familiarity accuracy did increase hippocampal activity linearly, although at an uncorrected level. This finding occurred although cued word recall and familiarity memory seemed matched with respect to information in memory. The detailed characteristics of these effects do not prove that word familiarity is exceptional in having hippocampal neural correlates. They suggest instead that participants fail to identify some aspects of recollection, misreporting it as familiarity, a problem with word-like items that have strong and recallable semantic associates.

Spatial navigation deficits in amnestic mild cognitive impairment with neuropsychiatric comorbidity.

AIMS: To find out whether neuropsychiatric comorbidity (comMCI) influences spatial navigation performance in amnestic mild cognitive impairment (aMCI). METHODS: We recruited aMCI patients with (n = 21) and without (n = 21) neuropsychiatric comorbidity or alcohol abuse, matched for global cognitive impairment and cognitively healthy elderly participants (HE, n = 22). They completed the Mini-Mental State Examination and a virtual Hidden Goal Task in egocentric, allocentric, and delayed recall subtests. RESULTS: In allocentric navigation, aMCI and comMCI performed significantly worse than HE and similarly to each other. Although aMCI performed significantly worse at egocentric navigation than HE, they performed significantly better than patients with comMCI. CONCLUSIONS: Despite the growing burden of dementia and the prevalence of neuropsychiatric symptoms in the elderly population, comMCI remains under-studied. Since trials often assess "pure" aMCI, we may underestimate patients' navigation and other deficits. This finding emphasizes the importance of taking account of the cognitive effects of psychiatric disorders in aMCI.

Personal semantic and episodic autobiographical memories in Korsakoff syndrome: A comparison of interview methods.

OBJECTIVE: The temporal gradient in patients with Korsakoff's syndrome has been of particular interest in the literature, as many studies have found evidence for a steep temporal gradient, but others have observed more uniform remote memory impairment across all past time periods. Inconsistencies might be the result of the nature of remote memory impairment under study (i.e., nonpersonal or autobiographical memory) and of methodological differences in the examination of remote memory loss. The aim of this study was to examine whether differences between autobiographical memory interview (AMI) and autobiographical interview (AI) procedures influence the presence of a temporal gradient in semantic and episodic autobiographical memory in Korsakoff patients. METHOD: The procedure used in the present study combined the AMI and AI into one study session. We compared the performance of 20 patients with Korsakoff's syndrome and 27 healthy controls. First, participants were asked to recall knowledge from different life periods. Second, participants were asked to recall memories from five life periods. Thirdly, participants were asked to rate their subjective experience of each event recalled on a 5-point scale. Finally, we analyzed the findings in terms of all the memories recalled versus the first memory from each life-period only. RESULTS: Both the AMI and the AI showed a temporally graded retrograde amnesia in the Korsakoff patients for personal semantic and episodic autobiographical memories. The pattern of amnesia in Korsakoff patients was not affected by examining only one event per life-period. Subjective ratings of recalled memories were largely comparable between the groups. CONCLUSIONS: The findings were generally consistent across the AMI and AI. Varying the number of events did not affect the pattern of the gradient. Hence, the temporal gradient in Korsakoff patients is not an artefact of either the AMI or the AI method.

Material Specificity Drives Medial Temporal Lobe Familiarity But Not Hippocampal Recollection.

The specific role of the perirhinal (PRC), entorhinal (ERC) and parahippocampal cortices (PHC) in supporting familiarity-based recognition remains unknown. An fMRI study explored whether these medial temporal lobe (MTL) structures responded in the same way or differentially to familiarity as a function of stimulus type at recognition. A secondary aim was to explore whether the hippocampus responds in the same way to equally strong familiarity and recollection and whether this is influenced by the kind of stimulus involved. Univariate and multivariate analyses revealed that familiarity responses in the PRC, ERC, PHC and the amygdala are material-specific. Specifically, the PRC and ERC selectively responded to object familiarity, while the PHC responded to both object and scene familiarity. The amygdala only responded to familiarity memory for faces. The hippocampus did not respond to stimulus familiarity for any of the three types of stimuli, but it did respond to recollection for all three types of stimuli. This was true even when recollection was contrasted to equally accurate familiarity. Overall, the findings suggest that the role of the MTL neocortices and the amygdala in familiarity-based recognition depends on the kind of stimulus in memory, whereas the role of the hippocampus in recollection is independent of the type of cuing stimulus. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.

mHealth and memory aids: levels of smartphone ownership in patients.

BACKGROUND: The use of mobile devices to deliver healthcare has not yet been exploited in neuropsychological rehabilitation. Smartphones have the potential to serve as multi-functional memory aids. AIMS: To investigate whether patients attending a clinic for mixed memory problems own smartphones, to determine whether this could be a widely applicable medium to use as a memory aids device. METHODS: A questionnaire on smartphone ownership was given to an opportunity sample of consecutive patients attending a neuropsychiatry and memory disorders outpatient clinic. Data were collected in 2012 and repeated 12 months later in 2013 to assess changes over time. RESULTS: Ownership of mobile phones was stable between 2012 (81%) and 2013 (85%), but ownership of smartphones showed a significant increase (from 26% to 40%). Age negatively predicted smartphone ownership. CONCLUSION: Despite cognitive or psychiatric problems, our patient group are as likely to own a mobile phone as a member of the general population. Ownership levels are at 40% and likely to increase in the future. Exploring how smartphones and their apps could function as memory aids is likely to be useful for a large enough number of patients to be clinically worthwhile.

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.

Effects of risperidone, amisulpride and nicotine on eye movement control and their modulation by schizotypy.

RATIONALE: The increasing demand to develop more efficient compounds to treat cognitive impairments in schizophrenia has led to the development of experimental model systems. One such model system combines the study of surrogate populations expressing high levels of schizotypy with oculomotor biomarkers. OBJECTIVES: We aimed (1) to replicate oculomotor deficits in a psychometric schizotypy sample and (2) to investigate whether the expected deficits can be remedied by compounds shown to ameliorate impairments in schizophrenia. METHODS: In this randomized double-blind, placebo-controlled study 233 healthy participants performed prosaccade (PS), antisaccade (AS) and smooth pursuit eye movement (SPEM) tasks after being randomly assigned to one of four drug groups (nicotine, risperidone, amisulpride, placebo). Participants were classified into medium- and high-schizotypy groups based on their scores on the Schizotypal Personality Questionnaire (SPQ, Raine (Schizophr Bull 17:555-564, 1991)). RESULTS: AS error rate showed a main effect of Drug (p < 0.01), with nicotine improving performance, and a Drug by Schizotypy interaction (p = 0.04), indicating higher error rates in medium schizotypes (p = 0.01) but not high schizotypes under risperidone compared to placebo. High schizotypes had higher error rates than medium schizotypes under placebo (p = 0.03). There was a main effect of Drug for saccadic peak velocity and SPEM velocity gain (both p ≤ 0.01) indicating impaired performance with risperidone. CONCLUSIONS: We replicate the observation of AS impairments in high schizotypy under placebo and show that nicotine enhances performance irrespective of group status. Caution should be exerted in applying this model as no beneficial effects of antipsychotics were seen in high schizotypes.

A visual object stimulus database with standardized similarity information.

Although many visual stimulus databases exist, none has data on item similarity levels for multiple items of each kind of stimulus. We present such data for 50 sets of grayscale object photographs. Similarity measures between pictures in each set (e.g., 25 different buttons) were collected using a similarity-sorting method (Goldstone, Behavior Research Methods Instruments & Computers, 26(4):381-386, 1994). A validation experiment used data from 1 picture set and compared responses from standard pairwise measures. This showed close agreement. The similarity-sorting measures were then standardized across picture sets, using pairwise ratings. Finally, the standardized similarity distances were validated in a recognition memory experiment; false alarms increased when targets and foils were more similar. These data will facilitate memory and perception research that needs to make comparisons between stimuli with a range of known target-foil similarities.

Measuring recollection and familiarity: Improving the remember/know procedure.

The remember/know (RK) procedure is the most widely used method to investigate recollection and familiarity. It uses trial-by-trial reports to determine how much recollection and familiarity contribute to different kinds of recognition. Few other methods provide information about individual memory judgements and no alternative allows such direct indications of recollection and familiarity influences. Here we review how the RK procedure has been and should be used to help resolve theoretical disagreements about the processing and neural bases of components of recognition memory. Emphasis is placed on procedural weaknesses and a possible confound of recollection and familiarity with recognition memory strength. Recommendations are made about how to minimise these problems including using modified versions of the procedure. The proposals here are important for improving behavioural and lesion research, and vital for brain imaging work.

British English norms for the spontaneous completion of three-letter word stems.

Word stem completion tasks involve showing participants a number of words and then later asking them to complete word stems to make a full word. If the stem is completed with one of the studied words, it indicates memory. It is a test widely used to assess both implicit and explicit forms of memory. An important aspect of stimulus selection is that target words should not frequently be generated spontaneously from the word stem, to ensure that production of the word really represents memory. In this article, we present a database of spontaneous stem completion rates for 395 stems from a group of 80 British undergraduate psychology students. It includes information on other characteristics of the words (word frequency, concreteness, imageability, age of acquisition, common part of speech, and number of letters) and, as such, can be used to select suitable words to include in a stem completion task. Supplemental materials for this article may be downloaded from http://brm.psychonomic-journals.org/content/supplemental.

A novel test of conditioned inhibition correlates with personality measures of schizotypy and reward sensitivity.

Conditioned inhibition is demonstrated when the meaning of one signal (conditioned stimulus, CS) is qualified by another (conditioned inhibitor, CI). Whilst the CS presented alone reliably predicts the outcome (unconditioned stimulus, US), when presented in conjunction with the CI the otherwise expected US will not occur. Conditioned inhibition has long been established in animal research but there have been difficulties in establishing reliable procedures suitable for use in human research. Such procedures are necessary to investigate disorders in which cognitive inhibitory mechanisms are known to be deficient, e.g., schizophrenia. In healthy participants, individual differences in the tendency to show conditioned inhibition should be related to personality measures of cognitive inhibition. In the present study, this was measured using an automated test procedure, in which visual stimuli predict the occurrence or non-occurrence of a visual outcome US, and BIS/BAS and schizotypy scales. Conditioned inhibition was reliable across two alternative test variants, in which the non-occurrence of the US was specified differently, and was confirmed by summation tests. The level of CI shown was positively associated with BAS Reward Responsiveness but did not correlate significantly with any of the other BIS/BAS scales. Conversely, the level of CI shown was negatively associated with schizotypy. We suggest that this novel conditioned inhibition task should now be applied to investigate a range of disorders that have some basis in dysfunctional inhibitory processes, such as schizophrenia.