The impact of time and repeated exposure on famous person knowledge in amnestic mild cognitive impairment and Alzheimer's disease.

OBJECTIVE: Famous people knowledge has been shown to be impaired early in Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI). However, the question of whether recently acquired knowledge is more impaired than remotely acquired knowledge remains a matter of debate. The aim of this study was to investigate the patterns of semantic memory impairment in aMCI and AD by investigating 2 factors that may influence the retrieval of such knowledge, namely remoteness and frequency of repetition of information over time. METHOD: Three groups (19 controls, 20 aMCI, and 20 AD patients) were compared on a test assessing general and specific biographical knowledge about famous people, where the period of acquired fame (remote vs. recent) and the type of fame (enduring vs. transient) were controlled for. RESULTS: Global performance of aMCI and AD patients was significantly poorer than that of controls. However, different patterns of recall were observed as a function of time and type of fame. A temporal gradient was found in both patient groups for enduring names but not for transient ones, whereby knowledge about remote enduring famous persons was better recalled. Patients were more impaired at questions assessing specific biographical knowledge (unique to an individual) than more general knowledge. CONCLUSIONS: Tests of famous people knowledge offer a unique opportunity to investigate semantic deficits in aMCI and AD, because they make it possible to estimate the time at which memories were acquired, as well as the type of fame. Results are discussed in light of memory consolidation models. (PsycINFO Database Record

Memory for Public Events in Mild Cognitive Impairment and Alzheimer's Disease: The Importance of Rehearsal.

Ribot's law refers to the better preservation of remote memories compared with recent ones that presumably characterizes retrograde amnesia. Even if Ribot-type temporal gradient has been extensively studied in retrograde amnesia, particularly in Alzheimer's disease (AD), this pattern has not been consistently found. One explanation for these results may be that rehearsal frequency rather than remoteness accounts for the better preservation of these memories. Thus, the aim of present study was to address this question by studying retrograde semantic memory in subjects with amnestic mild cognitive impairment (aMCI) (n = 20), mild AD (n = 20) and in healthy older controls (HC; n = 19). In order to evaluate the impact of repetition as well as the impact of remoteness, we used a test assessing memory for enduring and transient public events that occurred in the recent and remote past. Results show no clear temporal gradient across time periods (1960-1975; 1976-1990; 1991-2005; 2006-2011), but a better performance was observed in all three groups for enduring compared with transient events. Moreover, although deficits were globally found in both patients groups compared with HC, more specific analyses revealed that aMCI patients were only impaired on transient events while AD patients were impaired on both transient and enduring events. Exploratory analyses also revealed a tendency suggesting preservation of remote transient events in aMCI. These findings are discussed with regards to memory consolidation models.

[The evaluation of the retrograde memory in the Quebec population aged: PUB-40 and PUB-12]. / L'évaluation de la mémoire rétrograde dans la population Québécoise âgée: Le PUB-40 et le PUB-12.

Memory assessment represents an important part of the clinical neuropsychologist's duties in a geriatric context. In fact, in Canada, about one-third of seniors report memory complaints, with different causes. Based on the underlying etiology, different components of memory may be affected in older adults. Nonautobiographical retrograde memory (public or semantic) is an important aspect of memory to assess; nevertheless, there is currently no reliable and standardized clinical tool to evaluate this aspect of memory in the elderly Quebecer population. The aims of this research were therefore: (1) to develop a protocol specifically aimed at assessing non-autobiographical retrograde memory in this population, the PUB-40; (2) to obtain reference data among 105 healthy subjects; and (3) to develop a short version based on the items which discriminated a group of 20 patients with amnestic Mild cognitive impairment (aMCI) from older healthy subjects.

Contribution of night and day sleep vs. simple passage of time to the consolidation of motor sequence and visuomotor adaptation learning.

There is increasing evidence supporting the notion that the contribution of sleep to consolidation of motor skills depends on the nature of the task used in practice. We compared the role of three post-training conditions in the expression of delayed gains on two different motor skill learning tasks: finger tapping sequence learning (FTSL) and visuomotor adaptation (VMA). Subjects in the DaySleep and ImmDaySleep conditions were trained in the morning and at noon, respectively, afforded a 90-min nap early in the afternoon and were re-tested 12 h post-training. In the NightSleep condition, subjects were trained in the evening on either of the two learning paradigms and re-tested 12 h later following sleep, while subjects in the NoSleep condition underwent their training session in the morning and were re-tested 12 h later without any intervening sleep. The results of the FTSL task revealed that post-training sleep (day-time nap or night-time sleep) significantly promoted the expression of delayed gains at 12 h post-training, especially if sleep was afforded immediately after training. In the VMA task, however, there were no significant differences in the gains expressed at 12 h post-training in the three conditions. These findings suggest that "off-line" performance gains reflecting consolidation processes in the FTSL task benefit from sleep, even a short nap, while the simple passage of time is as effective as time in sleep for consolidation of VMA to occur. They also imply that procedural memory consolidation processes differ depending on the nature of task demands.

Motor sequence learning increases sleep spindles and fast frequencies in post-training sleep.

STUDY OBJECTIVES: To investigate polysomnographic (PSG) sleep and NREM sleep characteristics, including sleep spindles and spectral activity involved in offline consolidation of a motor sequence learning task. DESIGN: Counterbalanced within-subject design. SETTING: Three weekly visits to the sleep laboratory. PARTICIPANTS: Fourteen healthy participants aged between 20 and 30 years (8 women). INTERVENTIONS: Motor sequence learning (MSL) task or motor control (CTRL) task before sleep. MEASUREMENTS AND RESULTS: Subjects were trained on either the MSL or CTRL task in the evening and retested 12 hours later the following morning on the same task after a night of PSG sleep recording. Total number and duration of sleep spindles and spectral power between 0.5 and 24 Hz were quantified during NREM sleep. After performing the MSL task, subjects exhibited a large increase in number and duration of sleep spindles compared to after the CTRL task. Higher sigma (sigma; 13 Hz) and beta (beta; 18-20 Hz) spectral power during the post-training night's sleep were also observed after the MSL task. CONCLUSIONS: These results provide evidence that sleep spindles are involved in the offline consolidation of a new sequence of finger movements known to be sleep dependent. Moreover, they expand on prior findings by showing that changes in NREM sleep following motor learning are specific to consolidation (and learning), and not to nonspecific motor activity. Finally, these data demonstrate, for the first time, higher fast rhythms (beta frequencies) during sleep after motor learning.