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See detailRelating pessimistic memory predictions to Alzheimer’s disease brain structure
Genon, Sarah ULg; Simon, Jessica ULg; Bahri, Mohamed Ali ULg et al

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (in press)

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory ... [more ▼]

Patients with Alzheimer’s disease (AD) show impairment of episodic memory and related metacognitive processes. The present study examined subjective metacognitive judgments preceding objective memory retrieval and investigated the neural correlates of pessimistic predictions for successfully retrieved memories in AD patients. AD patients and healthy older participants provided predictive judgements on their recognition performance before retrieval of famous (semantic) and recently learned (episodic) names. Correlations between grey matter volume (GMV) in T1 images and behavioural scores were examined with multivariate (PLS) and univariate (GLM) analyses in AD patients. AD patients showed a significant proportion of successful name recognition preceded by pessimistic prediction (Prediction_low_hits) in episodic memory. PLS revealed that behavioural pattern in AD patients was related with a mainly right lateralized pattern of GMV decrease including medial temporal lobe and posterior cingulate cortex, but also right ventrolateral prefrontal cortex (VLPFC). GLM further confirmed that pessimistic prediction negatively correlated with GMV in VLPFC. Thus, impaired monitoring processes (possibly influenced by inaccurate beliefs) allowing inferences about one’s own memory performance are primarily related to decrease GMV in VLPFC in AD patients. [less ▲]

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See detailImpact du nombre d’alternatives lors d’une tâche de reconnaissance à choix-forcé sur les processus de reconnaissance dans le vieillissement normal
Simon, Jessica ULg; Gilsoul, Jessica ULg; Bastin, Christine ULg

Poster (2016, September 19)

Les tâches de reconnaissance à choix forcé sont classiquement utilisées pour évaluer la mémoire de reconnaissance. Cependant, aucune étude n’a spécifiquement investigué l’impact du nombre d’alternatives ... [more ▼]

Les tâches de reconnaissance à choix forcé sont classiquement utilisées pour évaluer la mémoire de reconnaissance. Cependant, aucune étude n’a spécifiquement investigué l’impact du nombre d’alternatives sur les performances mnésiques des participants âgés. Nous voulons déterminer, d’une part, si le nombre d’alternatives proposées - deux ou trois – et d’autre part, si le degré de similarité entre la cible et ses leurres ont un impact sur les stratégies de récupération mises en place au cours de la tâche. Pour ce faire, nous avons recruté 20 participants jeunes et 20 participants âgés. Lors de la tâche de reconnaissance, nous leur avons demandé de choisir, parmi deux ou trois photographies de visages, celui qui a été présenté précédemment. Certains couples cibles-leurres étaient plus similaires que d’autres (partage de 60% de caractéristiques communes, contre 40%). Pour chaque item sélectionné, les participants devaient expliquer ce qui a guidé leur choix. Les premières analyses (ANOVA à mesures répétées 2 (groupes) x 2 (alternatives) x 2 (similarité) sur les deux dernières mesures, p<0,05) montrent que les performances entre les groupes sont équivalentes pour la tâche de reconnaissance à deux alternatives. A l’inverse, nous avons observé que les participants jeunes avaient significativement de meilleures performances que les âgés dans la tâche de reconnaissance à trois alternatives. Les profils mnésiques des participants seront étudiés à la lumière des modèles à deux processus de la reconnaissance. Nous faisons l’hypothèse d’un recours plus fréquent à la recollection chez les jeunes dans la tâche de reconnaissance à trois alternatives (vs deux alternatives), alors que le choix de l’item se ferait chez les âgés, en comparant directement les degrés de familiarité associés à chaque item et en sélectionnant le plus familier (Norman & O’Reilly, 2003). [less ▲]

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See detailRecollection versus familiarity in normal aging and in mild cognitive impairment: Impact of test format.
Simon, Jessica ULg; Gilsoul, Jessica ULg; SALMON, Eric ULg et al

Poster (2016, July 18)

The aim of this study was to investigate the impact of test format on recollection and familiarity in normal aging and in MCI. Seventy young participants, 65 younger-old, 53 older-old, and 13 MCIs were ... [more ▼]

The aim of this study was to investigate the impact of test format on recollection and familiarity in normal aging and in MCI. Seventy young participants, 65 younger-old, 53 older-old, and 13 MCIs were presented with forced-choice and yes/no visual recognition memory tasks with the Remember/Know/Guess paradigm. The young people had better recognition performance than younger-old, who performed better than older-old and MCIs. Recollection and familiarity declined progressively in healthy aging. In MCI, recollection was more affected than familiarity, but patients demonstrated a more liberal use of familiarity. Finally, test format did not influence strongly the results. Young people used recollection more often in the forced-choice task compared to the yes/no task. [less ▲]

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See detailRecollection and Familiarity in Normal Aging
Simon, Jessica ULg; Gilsoul, Jessica ULg; Bastin, Christine ULg

Conference (2016, May 11)

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See detailRecollection versus familiarity in normal aging and in mild cognitive impairment: Impact of test format
Gilsoul, Jessica ULg; Simon, Jessica ULg; SALMON, Eric ULg et al

Poster (2016, March 18)

Objectives. Memory retrieval typically involves a combination of recollection and familiarity. However, test format can promote one or the other process (Norman & O’Reilly, 2003). The aim of this study ... [more ▼]

Objectives. Memory retrieval typically involves a combination of recollection and familiarity. However, test format can promote one or the other process (Norman & O’Reilly, 2003). The aim of this study was to investigate the impact of test format on recollection and familiarity in normal aging and in mild cognitive impairment (MCI). Methods. Seventy young participants (18-30 years), 65 “younger-old” (55- 69 years), 53 “older-old” (70-85 years), and 13 MCIs (55-82 years) were enrolled. In the “forced-choice” task, they had to recognize which picture, among three, was presented during the encoding stage. In the “yes/no” task, they had to judge whether each item, successively presented, was previously seen or not. In each task, they had to give a “Remember/Know/Guess” judgment. Results. Group × Format repeated measures ANOVAs revealed that young people had better recognition performance (d’) than “younger-old”, which were better than “older-old” and MCIs. Moreover, young people used familiarity more accurately than both groups of old participants and MCIs, with MCIs being equivalent to “younger-old” and “older-old”. However, MCIs displayed a high rate of familiarity-based false alarms. The resort to recollection decreased with age and in MCIs. Finally, Group × Format interaction revealed that young people (but not the other groups) could use recollection more often in the “forcedchoice” task compared to the “yes/no” task. Conclusions. Recollection and familiarity decline progressively in healthy aging. In MCI, recollection is more affected than familiarity, but patients demonstrated a more liberal use of familiarity. Finally, test format did not influence strongly the results. [less ▲]

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See detailThe impact of cognitive reserve on recognition memory performance is dependent of the task format in healthy aging
Simon, Jessica ULg; Gilsoul, Jessica ULg; Bastin, Christine ULg

Poster (2016, March 17)

Objective: According to the cognitive reserve hypothesis (Stern, 2009), individuals who have developed a high level of reserve should resist better to the effects of aging than individuals with lower ... [more ▼]

Objective: According to the cognitive reserve hypothesis (Stern, 2009), individuals who have developed a high level of reserve should resist better to the effects of aging than individuals with lower cognitive reserve. In this study, we identified the factors of cognitive reserve that impact most memory performance in aging. Methods: 118 healthy older participants performed one yes/no recognition task and one 3-alternative forced-choice recognition task. For each recognized item, participants provided a Remember/Know/Guess judgment. Furthermore, participants completed a questionnaire assessing different aspects of cognitive reserve (level of education, occupation, physical, social, cultural and intellectual activities). We determined the moderators of cognitive reserve that explain a significant proportion of variance for each memory index through stepwise regression analyzes (p<0.05). Results: In the forced-choice test, the level of education explained positively the use of recollection and negatively the level of false alarms associated with familiarity. In the yes/no recognition task, the precision of recognition was explained positively by the physical activities. Recollection was positively explained by the physical activities and the level of education. Finally, the level of false alarms associated with familiarity was explained negatively by the level of education although the precision of the use of the familiarity is explained positively by physical activities. Conclusion: The more older adults were educated and/or were practicing physical activities, the better their recollection was. The impact of the moderators of the cognitive reserve is dependent on the format of the recognition task. [less ▲]

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See detailLe fonctionnement exécutif dans le vieillissement normal: Quel rôle accorder aux variables attentionnelles ?
Gilsoul, Jessica ULg; Simon, Jessica ULg; Collette, Fabienne ULg

Conference (2015, December 04)

Introduction. Selon Miyake et al. (2000), le fonctionnement exécutif serait sous-tendu par trois fonctions distinctes - l’inhibition, la flexibilité et la mise à jour - alors que d’autres auteurs (Fisk ... [more ▼]

Introduction. Selon Miyake et al. (2000), le fonctionnement exécutif serait sous-tendu par trois fonctions distinctes - l’inhibition, la flexibilité et la mise à jour - alors que d’autres auteurs (Fisk & Sharp, 2004) suggèrent qu’elles seraient au nombre de quatre (coordination de tâche double). On sait aujourd’hui que l’avancée en âge s’accompagne d’un déclin exécutif. Toutefois, peu d’études ont étudié l’impact de variables non-exécutives (et plus particulièrement attentionnelles) sur la variabilité des performances exécutives dans le vieillissement. Méthode. 114 participants jeunes et 65 participants âgés ont réalisé un ensemble de tâches cognitives évaluant les quatre aspects du fonctionnement exécutif : l’inhibition (Stroop, Anti-saccade, Stop-Signal), la flexibilité (Plus et Moins, Chiffres-Lettres, Global-Local), la mise à jour (Mise à jour sonore, Mise à jour sémantique, Mise à jour de consonnes) et la coordination de tâche double (PASAT, Brown-Peterson, Attention divisée (TEA)). Par ailleurs, nous avons mesuré la vitesse de traitement de l’information (Comparaison de lettres, Stop-signal contrôle, Alerte tonique, Vitesse articulatoire), le fonctionnement attentionnel dans ses aspects d’alerte phasique, d’orientation visuelle externe (Balayage visuel, Motilité oculaire) et d’attention soutenue (Détection d’irrégularités visuelles, Détection de cibles), ainsi que le niveau d’empan. Nous avons tout d’abord comparé les performances des deux groupes sur chacune des tâches exécutives. Pour celles où nous avons observé une différence entre les groupes, nous avons tenté de déterminer si certaines variables non-exécutives pourraient expliquer une part de la variance des performances de nos participants âgés. Résultats. Les comparaisons entre groupes révèlent que les sujets jeunes ont toujours (sauf pour la tâche Stop-Signal) des performances exécutives supérieures à celles des âgés (p<0.01). Lorsque les différentes variables attentionnelles et non-attentionnelles sont introduites dans un modèle de régression multiple stepwise pas à pas, nous observons que les variables attentionnelles expliquent une part significative de la variance pour la tâche Chiffres-Lettres (alerte), la tâche de Mise à jour sémantique (orientation visuelle externe), la tâche de Mise à jour de consonnes (orientation visuelle externe) et la tâche d’attention divisée (alerte et orientation visuelle externe). Discussion. En accord avec de précédentes études, le fonctionnement exécutif décline avec l’âge. Nos résultats indiquent que le déclin de certaines fonctions (mais pas toutes) serait modulé par les capacités attentionnelles. Cette modulation attentionnelle ne serait toutefois pas un processus général, mais dépendrait des caractéristiques propres à chaque tâche. [less ▲]

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See detailImpact du format du test sur la recollection et la familiarité dans le vieillissement normal et le trouble cognitif léger de type amnésique
Simon, Jessica ULg; Gilsoul, Jessica ULg; SALMON, Eric ULg et al

Conference (2015, December 04)

Les tâches de reconnaissance à choix-forcé et oui/non ont largement été utilisées dans l’évaluation de la mémoire. Selon Norman et O’Reilly (2003), le format oui/non ferait davantage intervenir la ... [more ▼]

Les tâches de reconnaissance à choix-forcé et oui/non ont largement été utilisées dans l’évaluation de la mémoire. Selon Norman et O’Reilly (2003), le format oui/non ferait davantage intervenir la recollection alors que le format à choix-forcé favoriserait la comparaison du sentiment de familiarité associé à chaque item et la sélection du plus familier. L’objectif de cette étude est d’explorer l’impact du format du test sur la recollection et la familiarité au travers du vieillissement normal et pathologique. Septante participants jeunes (18 - 30 ans), 65 participants jeunes-âgés (55 - 69 ans), 53 participants âgés-âgés (70-85 ans) et 13 patients présentant un trouble cognitif léger amnésique (55-82 ans) ont réalisé deux tâches de reconnaissance. Pour chaque tâche, lors de l’encodage, nous avons présenté, à deux reprises, 25 images à mémoriser. Dans la tâche de reconnaissance à choix forcé, les participants devaient reconnaitre parmi trois images très semblables celle qui a été vue précédemment. Dans la tâche de reconnaissance oui/non, les items étaient présentés successivement et les participants devaient reconnaitre ceux présentés à l’encodage. Pour chaque item reconnu, les participants devaient fournir un jugement Remember/Know/Guess. Les ANOVA Groupe x Format à mesures répétées sur la dernière variable (p<0,05) ont révélé que les jeunes avaient de meilleures performances en reconnaissance (score d’) que les jeunes-âgés, qui ont eux-mêmes de meilleures performances que les âgés-âgés et les patients. En outre, les jeunes utilisent plus souvent le sentiment de familiarité pour reconnaître les images étudiées que les participants âgés et les patients. De plus, les participants jeunes-âgés utilisent plus souvent la familiarité que les participants âgés-âgés, alors qu’il n’y a pas de différence entre ceux-ci et les patients. Cependant, les fausses alarmes associées à la familiarité augmentent progressivement dans le vieillissement et la pathologie. L’utilisation de la recollection est progressivement réduite avec l’âge et altérée dans la pathologie. Enfin, les jeunes tendent à utiliser plus souvent la recollection dans la tâche à choix-forcé (p=0,055), alors qu’il n’y a pas de différence pour les autres groupes. Tous ces résultats suggèrent que le vieillissement normal s’accompagne d’un déclin progressif de la recollection et de la familiarité. Dans le vieillissement pathologique, on observe des performances similaires au groupe le plus âgé en reconnaissance malgré un déficit de recollection. Les patients utilisent la familiarité autant que les deux groupes âgés bien que les taux de fausses alarmes soient plus importants, suggérant une utilisation privilégiée mais inadéquate de ce processus. [less ▲]

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See detailThe executive functioning in normal aging: Impact of the cognitive reserve
Simon, Jessica ULg; Gilsoul, Jessica ULg; Collette, Fabienne ULg

Poster (2015, September 04)

There exists a large inter-individual variability regarding the effects of aging on cognition. According to Stern (2009), people who developed a high level of reserve are more resilient to the effects of ... [more ▼]

There exists a large inter-individual variability regarding the effects of aging on cognition. According to Stern (2009), people who developed a high level of reserve are more resilient to the effects of aging that individuals with lower cognitive reserve. In this study, we describe the impact of cognitive reserve on executive functions in normal aging. Ninety healthy participants aged from 60 to 80 years were recruited. We assessed the three major executive functions: Inhibition (Stroop test, Hayling test, TAP Incompatibility subtest), Shifting (TAP Flexibility subtest, Plus-Minus task), and Updating (Letter-Number Sequencing subtest from MEM III, Letter memory task, 2-back task). Cognitive reserve was measured by questionnaires assessing educational level, occupation, leisure activities and physical activity across the life. Multiple linear regressions (p<0.05) adjusted for age, quality of sleep, processing speed showed that elderly with a high level of reserve have better performance on updating. We also assessed the effect of each factor of cognitive reserve separately after adjustment for the other. We observed that people with high level of education have better performance on flexibility (TAP Flexibility subtest and composite score) and on updating (Letter-Number Sequencing subtest, Letter memory and composite score). However, we didn’t observe any significant effect of the other factors of cognitive reserve. These results suggest that the cognitive reserve is related to abilities in some executive tests. [less ▲]

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See detailExecutive functions in normal aging: Impact of cognitive reserve and objective physical activity
Gilsoul, Jessica ULg; Simon, Jessica ULg; Collette, Fabienne ULg

Poster (2015, May 28)

It is now acknowledged that there exists a large inter-individual variability in age-related cognitive changes. According to Stern (2009), the cognitive reserve built up throughout the life span will make ... [more ▼]

It is now acknowledged that there exists a large inter-individual variability in age-related cognitive changes. According to Stern (2009), the cognitive reserve built up throughout the life span will make seniors more or less resilient to the deleterious effects of aging on cognition, with seniors having a high level of cognitive reserve being more prone to successfully cope with cognitive and neuronal changes. Currently, few studies have focused on the specific effects of different factors of cognitive reserve on cognition. Consequently, the objective of this study is to determine the impact of four determinants of cognitive reserve on executive functions in normal aging. Sixty-eight healthy participants aged 60 to 80 were enrolled. Regarding executive functions, Inhibition (Stroop test, Hayling test, TAP Incompatibility subtest), Shifting (TAP Flexibility subtest, Plus-Minus task), and Updating (Letter-Number Sequencing subtest from MEM III, Letter memory task, 2-back task) were assessed (Miyake et al., 2000). Cognitive reserve was measured by questionnaires assessing educational level, occupation, leisure activities and physical activity. Moreover, an accelerometer allowed quantitative measure of physical activity by recording body movements during two weeks. Group comparisons (p<0.05) showed that seniors with a high level of cognitive reserve (measured by a global composite z-score) have better updating abilities (Letter memory task and updating composite score). In order to test the influence of each cognitive reserve factor on executive functions, simple linear regressions (p<0.05) were performed. The results showed that the educational level accounts for a significant part of the variance in flexibility (TAP Flexibility) and updating (Letter-Number sequencing, 2-back and composite score). The occupational level accounts significantly for the variance of the updating composite score. Regarding the quantitative physical activity, the mean number of minutes per day in moderate or intense physical activity significantly predicted the updating composite score. These results indicate that the level of cognitive reserve is related to abilities in some executive tests, particularly updating abilities. Importantly, all aspects of cognitive reserve are not associated with the three executive processes. This indicates a specificity of the protective effect of cognitive reserve on executive abilities. [less ▲]

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See detailL’impact du trouble cognitif léger et de la maladie d’Alzheimer sur la recollection et la familiarité
Simon, Jessica ULg; Bastin, Christine ULg

in Revue de Neuropsychologie (2015), 7(3), 177-188

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See detailL’impact de la réserve cognitive sur le fonctionnement exécutif au cours du vieillissement normal
Simon, Jessica ULg; Gilsoul, Jessica ULg; Collette, Fabienne ULg

Conference (2014, December 05)

Le vieillissement normal s’accompagne d’un dysfonctionnement exécutif important. Or, on sait aujourd’hui qu’il existe une forte variabilité interindividuelle quant aux effets du vieillissement sur la ... [more ▼]

Le vieillissement normal s’accompagne d’un dysfonctionnement exécutif important. Or, on sait aujourd’hui qu’il existe une forte variabilité interindividuelle quant aux effets du vieillissement sur la cognition. Selon l’hypothèse de la réserve cognitive (Stern, 2009), les individus qui auraient développé un haut niveau de réserve résisteraient mieux aux effets du vieillissement que des individus de plus faible réserve cognitive. Dans cette étude, nous avons voulu mesurer l’impact des facteurs de réserve cognitive sur le fonctionnement exécutif au cours du vieillissement normal. Nous avons recruté 59 participants âgés de 60 à 80 ans, sans trouble cognitif ni neurologique. Nous leur avons proposé 8 tâches cognitives évaluant le fonctionnement exécutif : des épreuves d’inhibition (test de Stroop, test de Hayling, subtest Incompatibilité de la TAP), de flexibilité (subtest Flexibilité de la TAP, épreuve d’alternance arithmétique « plus-moins ») et de mise à jour (subtest Lettre-Chiffre de la MEM III, mise à jour de consonnes et tâche de 2-back). De plus, nous leur avons demandé de compléter différents questionnaires évaluant quatre facteurs de réserve cognitive (niveau d’études, parcours professionnel, activité physique et activités de loisir). Nous avons réparti nos participants en deux groupes en fonction de leur niveau de réserve cognitive (faible et haute). Des analyses de t de student (p<0.05) montrent que les participants avec une haute réserve cognitive ont de meilleures performances au subtest de mise à jour des consonnes (p=0,05) ainsi que des résultats quasi significatif pour le score composite de mise à jour (p=0,06) et le subtest de mise de consonnes (p=0,06). Nous avons aussi évalué l’impact spécifique de chaque facteur de réserve cognitive sur les performances au moyen de régressions simples (p<0.05). Les données montrent que le niveau d’étude explique une part significative de la variance du score composite de mise à jour et aux subtests Flexibilité et Lettre-Chiffre ainsi qu’une part quasi significative de la variance au score de mise à jour de consonnes. L’activité professionnelle au cours de la vie explique une part quasi-significative de la variance pour le score de mise à jour (p=0,07) et pour le test de mise à jour de consonnes (p=0,07). Enfin, les activités de loisir, quant à elles, expliquent une part significative de la variance des performances à la tâche du 2-back et une part quasi-significative de la variance des performances au test de Hayling (p=0.06). En conclusion, il apparait que les sujets âgés avec un haut niveau de réserve cognitive montrent de meilleures capacités à certains tests exécutifs uniquement. De plus, nos données suggèrent que tous les aspects du fonctionnement exécutif ne sont pas impactés de façon similaire par les différents facteurs de réserve cognitive. [less ▲]

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See detailMémoire épisodique dans la maladie d’Alzheimer : Déclin de la remémoration consciente et de la familiarité ?
Simon, Jessica ULg; Bastin, Christine ULg

in Medecine Sciences : M/S (2014), 30

According to the dual-process recognition models, the retrieval of information from long-term memory is supported by recollection and familiarity. Alzheimer’s disease is consistently found to affect ... [more ▼]

According to the dual-process recognition models, the retrieval of information from long-term memory is supported by recollection and familiarity. Alzheimer’s disease is consistently found to affect recollection. As for familiarity, however, no consensus has been reached so far. Some studies are in favor of an early impairment of familiarity, while others are in favor of a preservation of familiarity in the mild and moderate stages of the disease. This lack of consensus can be partly explained by methodological differences between studies. We discuss three methodological dimensions: the type of recognition test, the type of paradigm for estimating familiarity and recollection, and the nature of the material used. These differences reveal the complex nature of familiarity which would be underlied by different mechanisms that may be selectively altered or preserved in the disease. [less ▲]

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See detailThe Impact of the Salience of Fluency in Recognition Memory in Alzheimer’s Disease
Simon, Jessica ULg; Bastin, Christine ULg; SALMON, Eric ULg et al

Poster (2014, March 11)

Introduction: According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes ... [more ▼]

Introduction: According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes. One of the most important mechanisms is the sense of familiarity driven by the fluency processing (Whittlesea, 1993). The fluency can be defined by the enhancement of processing speed and the ease of processing due to an earlier encounter with the stimulus. Our objective is to explore the effect on an increase of salience of fluency cues on the recognition memory performance of patients with Alzheimer disease (AD). Methods: Sixteen AD patients and sixteen healthy elderly controls (HC) performed two conditions of a memory task. In the study phase, 25 words were presented at a rate of one word every 1.5s. Participants were instructed to read the words aloud and to try and remember them. After a break of 5 minutes, participant performed a yes/no recognition task with 25 studied words and 25 new words. In the Non-Overlap condition, the 25 studied words were composed of a subset of letters of the alphabet and the 25 new words of the remaining letters. In the Overlap condition, the 50 words were based on the whole alphabet. The two recognition tasks were separated by a delay of 24h. Results: The capacity to discriminate between old and new items was measured by the index d’. A 2 (group) by 2 (condition) repeated measure ANOVA on d’ scores revealed that discrimination was poorer in the AD group than in the HC [F(1,30)=48.07, p<.001] and also poorer in the Overlap condition than in the Non-Overlap condition [F(1,30)=19.901, p<.001]. Conclusion: The current results showed that to increase salience of fluency at the level of letter by eliminating letter-overlap between old and new words increases the recognition performance to the same extent in both groups but the amplitude of AD memory deficit was not reduced (Bastin, Willems, Genon, & Salmon, 2013). [less ▲]

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See detailMetabolic cerebral correlates of conjunctive and relational memory in Alzheimer's disease
Bastin, Christine ULg; Bahri, Mohamed Ali ULg; Collette, Fabienne ULg et al

Poster (2014)

Introduction. Memory deficits are the clinical hallmark of typical Alzheimer’s disease. The precise nature of these deficits however remains to be fully characterized. In this study, we investigated ... [more ▼]

Introduction. Memory deficits are the clinical hallmark of typical Alzheimer’s disease. The precise nature of these deficits however remains to be fully characterized. In this study, we investigated binding in long-term episodic memory. Relational binding processes in memory create an associative link between independent items or between items and context into episodic memories (Cohen et al., 1999). An alternative process, conjunctive binding, allows associations to be encoded as a united representation of features into a single entity (O'Reilly and Rudy, 2001; Mayes et al., 2007). The current study (1) assessed whether Alzheimer’s disease disrupt both conjunctive and relational memory, and (2) related patients’ memory performance to cerebral metabolism. Methods. Thirty patients with mild Alzheimer’s disease and 24 healthy older adults performed a source memory task where items were associated to a background color (Diana et al., 2008, 2010). In one condition, relational binding was promoted by the instruction to associate the item with another object of the same color as the background. In the other condition, color had to be integrated as an item feature (conjunctive binding). Patients’ brain metabolic activity at rest (FDG-PET) was analysed with spatio-temporal Partial Least Squares (McIntosh et al., 1996) in order to assess the relation of behavioral performance and activity in functional cerebral networks. Results. Alzheimer’s disease 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 a significant pattern of metabolic activity that correlated specifically with each condition (accounting for 76.48 % of the covariance in the data; p< .05). More specifically, 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. Conclusions. 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. [less ▲]

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See detailThe impact of the salience of fluency in recognition memory in Alzheimer’s disease
Simon, Jessica ULg; Bastin, Christine ULg; SALMON, Eric ULg et al

Poster (2013, December 06)

According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes. One of the ... [more ▼]

According to the dual-process models, recognition memory is supported by recollection and familiarity (Yonelinas, 2002). Familiarity is a complex function that depends on several processes. One of the most important mechanisms is the sense of familiarity driven by the fluency processing (Whittlesea, 1993). The fluency can be defined by the enhancement of processing speed and the ease of processing due to an earlier encounter with the stimulus. Our objective is to explore the effect on an increase of salience of fluency cues on the recognition memory performance of patients with Alzheimer disease (AD). Sixteen AD patients and sixteen healthy elderly controls (HC) performed two conditions of a memory task. In the study phase, 25 words were presented at a rate of one word every 1.5s. Participants were instructed to read the words aloud and to try and remember them. After a break of 5 minutes, participant performed a yes/no recognition task with 25 studied words and 25 new words. In the Non-Overlap condition, the 25 studied words were composed of a subset of letters of the alphabet and the 25 new words of the remaining letters. In the Overlap condition, the 50 words were based on the whole alphabet. The two recognition tasks were separated by a delay of 24h. The capacity to discriminate between old and new items was measured by the index d’. An ANOVA on d’ scores revealed that discrimination was poorer in the AD group than in the HC and also poorer in the Overlap condition than in the Non-Overlap condition. The current results showed that to increase salience of fluency at the level of letter by eliminating letter-overlap between old and new words increases the recognition performance to the same extent in both groups but the amplitude of AD memory deficit was not reduced (Bastin, Willems, Genon, & Salmon, 2013). [less ▲]

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