Testing website usability in Spanish-Speaking Academia through heuristic evaluation and cognitive walkthroughs

Although usability evaluations have been focused on assessing different contexts of use, no proper specifications have been addressed towards the particular environment of academic websites in the Spanish-speaking context of use. Considering that this context involves hundreds of millions of potential users, the AIPO Association is running the UsabAIPO Project. The ultimate goal is to promote an adequate translation of international standards, methods and ideal values related to usability in order to adapt them to diverse Spanish-related contexts of use. This article presents the main statistical results coming from the Second and Third Stages of the UsabAIPO Project, where the UsabAIPO Heuristic method (based on Heuristic Evaluation techniques) and seven Cognitive Walkthroughs were performed over 69 university websites. The planning and execution of the UsabAIPO Heuristic method and the Cognitive Walkthroughs, the definition of two usability metrics, as well as the outline of the UsabAIPO Heuristic Management System prototype are also sketched.

Traumatismes précoces et réponses de stress, leur association aves la santé mentale, l'attachement et l'ocytocine

Lorsqu'un individu est confronté à une situation stressante, une des réponses les plus saillantes est l'activation de l'axe HPA, caractérisée par le déclenchement d'un taux élevé de glucocorticoïdes dans le sang. De manière générale, cette réponse hormonale est adaptative et elle a pour but la mobilisation des ressources physiques et cognitives de l'individu pour une action spécifique (Axelrod & Reisine, 1984; Chrousos & Gold, 1992; N. M. Kaplan, 1988; McEwen, 2004). Cependant, lorsque une personne est confrontée très tôt dans son développement, et de manière répétée, à des situations de stress, cette réponse physiologique peut s'altérer, devenir inadaptée (Anand, 1993; Bremner et al., 1995; Meaney et al., 1996; Mirescu, Peters, & Gould, 2004; Plotsky & Meaney, 1993; Sapolsky, 2000) et être associée à des troubles cognitifs (McEwen & Sapolsky, 1995) et émotionnels (McEwen, 2000). A l'âge adulte, le résultat de ces altérations psychoneuroendocriniennes se traduit au cours de l'activation de l'axe HPA et elles sont visibles lors de situations de stress moins intenses (Graham, Heim, Goodman, Miller, & Nemeroff, 1999; Mirescu et al., 2004; Stam, Bruijnzeel, & Wiegant, 2000; A. Taylor, Fisk, & Glover, 2000). La dysregulation de l'axe HPA semble représenter un facteur de vulnérabilité lié à des dysfonctionnements psychiques et physiologiques chez les adultes (Heim, Ehlert, & Hellhammer, 2000; Heim & Nemeroff, 1999; Heim, Newport, Mletzko, Miller, & Hemeroff, 2008). Cependant, des facteurs de protection peuvent influencer à leur tour ces vulnérabilités. La littérature, basée sur des études translationnelles (animaux, humains), converge vers le postulat selon lequel la dimension relationnelle apportée par l'environnement est fondamentale dans le développement des vulnérabilités physiologiques et psychiques du sujet. Dans ce sens, les relations d'attachement ont été particulièrement étudiées. A l'âge adulte, par exemple, la qualité des représentations d'attachement semble influencer directement l'expression de gènes impliqués dans les réponses hormonales de stress (Biagini, Pich, Carani, Marrama, & Agnati, 1998; Caldji, Diorio, & Meaney, 2000; Dallman, 2000; De Kloet, Rosenfeld, Van Eekelen, Sutanto, & Levine, 1988; Rincon-Cortes & Sullivan, 2014; Romeo, Tang, & Sullivan, 2009; van Oers, de Kloet, Whelan, & Levine, 1998), illustrant ainsi une perspective épigénétique. Traumatismes précoces et réponses de stress, leur association avec la santé mentale, l'attachement et l'ocytocine Deux objectifs principaux définissent ce travail de doctorat. Le premier est de comprendre comment un événement à portée traumatique, qui a eu lieu pendant la période périnatale, l'enfance ou l'adolescence, peut s'inscrire au niveau physiologique (axe hypotalamico- hypophysaire-surrénalien - axe HPA), au niveau psychopathologique ou encore au niveau de la régulation émotionnelle au cours de l'âge adulte. A ce propos, nous avons évalué les réponses physiologiques (telles que le Cortisol, l'ACTH et l'ocytocine), la présence de psychopathologies (relatives à l'axe I du DSM-IV) et les réponses émotionnelles (telles que la perception au stress) au cours d'une situation de stress de nature psychosociale, induite en laboratoire. Le deuxième objectif de ce travail est de savoir si les représentations d'attachement peuvent médiatiser ces effets, chez des individus exposés à différents événements à portée traumatique. Dans ce but, trois populations ont été considérées. La première est relative à des jeunes adultes nés grands prématurés ; la deuxième, concerne des femmes adultes ayant vécu un ou plusieurs abus sexuels au cours de leur enfance ou de leur adolescence et enfin la troisième est constituée de personnes adultes qui ont survécu à une maladie grave (cancer) pendant leur enfance ou leur adolescence. Enfin, ces trois populations sont comparées à des groupes contrôle. La prise en considération de différents types de traumatismes a permis de relever : premièrement, qu'un événement à portée traumatique de nature différente, peut influencer de manière semblable les structures neuronales, par exemple l'hypocortisolémie ; deuxièmement, qu'un dysfonctionnement de l'axe HPA n'aboutit pas nécessairement à la présence de signes de souffrance mentale ; enfin, des effets protecteurs ont été mis en évidence. Ces facteurs sont sous-tendus, d'un point de vue psychologique, par les représentations d'attachement et, d'un point de vue physiologique, par la sécrétion d'ocytocjne périphérique. Traumatismes précoces et réponses de stress, leur association avec la santé mentale, l'attachement et l'ocytocine -- When an individual is faced by a stressful situation, one of the most notable responses is the activation of the HPA axis, which is characterized by a heightened level of glucocortisoids in the blood. In general, this is an adaptive hormonal response which prepares the individual both physically and cognitively for a specific action (Axelrod & Reisine, 1984; Chrousos & Gold, 1992; N. M. Kaplan, 1988; McEwen, 2004). However, should a person be confronted to stressful situations very early and repeatedly in their development, this physiologic response may be altered and become maladapted (Anand, 1993; Bremner et al., 1995; Meaney et al., 1996; Mirescu et al., 2004; Plotsky & Meaney, 1993; Sapolsky, 2000) which can be associated to emotional (McEwen, 2000) and cognitive disorders(McEwen & Sapolsky, 1995). Throughout adulthood, the result of these psychoneuroendocrine alterations affects the activation of the HPA axis and are noticeable during less intense stressful situations (Graham et al., 1999; Mirescu et al., 2004; Stam et al., 2000; A. Taylor et al., 2000). HPA axis dysregulation appears to represent a factor of vulnerability linked to psychological and physical disorders in adults (Heim, Ehlert, et al., 2000; Heim & Nemeroff, 1999; Heim, Newport, et al., 2008). Nonetheless, these vulnerabilities may be influenced by further protection factors. The literature, based on translational studies (animals and humans), suggests that relationships formed in the context of the individual's environment are fundamental in the development of their physiological and psychological vulnerabilities. Thus, attachment relationships have been particularly studied. In adulthood, for example, the quality of attachment representations appear to influence directly the expression of genes involved in the hormonal responses to stress (Biagini et al., 1998; Caldji et al., 2000; Dallman, 2000; De Kloet et al., 1988; Rincon-Cortes & Sullivan, 2014; Romeo et al., 2009; van Oers et al., 1998). With the goal to study these dimensions, two principal objectives define these doctoral study. The first is to understand how an event considered to be traumatic, which took place during early infancy, infancy, or adolescence, could influence physiology (HPA axis), psychopathology or emotional regulation during adulthood. Therefore we have evaluated the presence of psychopathologies (relative to axis I of the DSM), physiological responses (such as Cortisol, ACTH and oxytocin) and emotional responses (such as perception of stress) throughout a psychosocial stress situation, conducted in a laboratory setting. The second objective of this study is to understand if attachment representations can mediate these effects, in individuals exposed to three different types of traumatic events. Therefore, three populations have been considered. The first is young adults who were born prematurely; the second concerns adult women who have suffered sexual abuse, on one or more occasions, during their childhood or adolescence; finally the third group is constituted of people who have survived a grave childhood illness. These populations were all compared to control groups. The consideration of different types of traumatic events has demonstrated, firstly, that different events which are considered to be traumatic can similarly influence neuronal structures, for example hypocortisolism. Secondly, that an HPA axis disorder does not necessarily lead to the presence of mental signs of distress, as is the case for those born very prematurely. Finally, protective effects were demonstrated, distinctively from a psychological point of view, by attachment representations and furthermore by peripheral oxytocin secretion from a physiological perspective.

Stability of cognitive performance in children with mild intellectual disability.

AIM: Longitudinal studies that have examined cognitive performance in children with intellectual disability more than twice over the course of their development are scarce. We assessed population and individual stability of cognitive performance in a clinical sample of children with borderline to mild non-syndromic intellectual disability. METHOD: Thirty-six children (28 males, eight females; age range 3-19y) with borderline to mild intellectual disability (Full-scale IQ [FSIQ] 50-85) of unknown origin were examined in a retrospective clinical case series using linear mixed models including at least three assessments with standardized intelligence tests. RESULTS: Average cognitive performance remained remarkably stable over time (high population stability, drop of only 0.38 IQ points per year, standard error=0.39, p=0.325) whereas individual stability was at best moderate (intraclass correlation of 0.58), indicating that about 60% of the residual variation in FSIQ scores can be attributed to between-child variability. Neither sex nor socio-economic status had a statistically significant impact on FSIQ. INTERPRETATION: Although intellectual disability during childhood is a relatively stable phenomenon, individual stability of IQ is only moderate, likely to be caused by test-to-test reliability (e.g. level of child's cooperation, motivation, and attention). Therefore, clinical decisions and predictions should not rely on single IQ assessments, but should also consider adaptive functioning and previous developmental history.

Cognitive Predictors and Risk Factors of PTSD Following Stillbirth: A Short-Term Longitudinal Study.

This short-term longitudinal study investigated cognitive predictors and risk factors of posttraumatic stress disorder (PTSD) in mothers following stillbirth. After a stillbirth at ≥ 24 weeks gestational age, 65 women completed structured clinical interviews and questionnaires assessing PTSD symptoms, cognitive predictors (appraisals, dysfunctional strategies), and risk factors (perceived social support, trauma history, obstetric history) at 3 and 6 months. PTSD symptoms decreased between 3 and 6 months (Cohen's d ranged .34-.52). Regression analyses also revealed a specific positive relationship between Rumination and concurrent frequency of PTSD symptoms (β = .45). Negative Self-View and Negative World-View related positively and Self-Blame related negatively to concurrent number of PTSD symptoms (β = .48, .44, -.45, respectively). Suppression and Distraction predicted a decrease and Numbing predicted an increase in time-lagged number of PTSD symptoms (β = -.33, -.28, .30, respectively). Risk factors for PTSD symptoms were younger age (β = -.25), lower income (β = -.29), fewer previous pregnancies (β = -.31), and poorer perceived social support (β = -.26). Interventions addressing negative appraisals, dysfunctional strategies, and social support are recommended for mothers with PTSD following stillbirth. Knowledge of cognitive predictors and risk factors of PTSD may inform the development of a screening instrument.

Copy number variations and cognitive phenotypes in unselected populations

IMPORTANCE: The association of copy number variations (CNVs), differing numbers of copies of genetic sequence at locations in the genome, with phenotypes such as intellectual disability has been almost exclusively evaluated using clinically ascertained cohorts. The contribution of these genetic variants to cognitive phenotypes in the general population remains unclear. OBJECTIVE: To investigate the clinical features conferred by CNVs associated with known syndromes in adult carriers without clinical preselection and to assess the genome-wide consequences of rare CNVs (frequency ≤0.05%; size ≥250 kilobase pairs [kb]) on carriers' educational attainment and intellectual disability prevalence in the general population. DESIGN, SETTING, AND PARTICIPANTS: The population biobank of Estonia contains 52,000 participants enrolled from 2002 through 2010. General practitioners examined participants and filled out a questionnaire of health- and lifestyle-related questions, as well as reported diagnoses. Copy number variant analysis was conducted on a random sample of 7877 individuals and genotype-phenotype associations with education and disease traits were evaluated. Our results were replicated on a high-functioning group of 993 Estonians and 3 geographically distinct populations in the United Kingdom, the United States, and Italy. MAIN OUTCOMES AND MEASURES: Phenotypes of genomic disorders in the general population, prevalence of autosomal CNVs, and association of these variants with educational attainment (from less than primary school through scientific degree) and prevalence of intellectual disability. RESULTS: Of the 7877 in the Estonian cohort, we identified 56 carriers of CNVs associated with known syndromes. Their phenotypes, including cognitive and psychiatric problems, epilepsy, neuropathies, obesity, and congenital malformations are similar to those described for carriers of identical rearrangements ascertained in clinical cohorts. A genome-wide evaluation of rare autosomal CNVs (frequency, ≤0.05%; ≥250 kb) identified 831 carriers (10.5%) of the screened general population. Eleven of 216 (5.1%) carriers of a deletion of at least 250 kb (odds ratio [OR], 3.16; 95% CI, 1.51-5.98; P = 1.5e-03) and 6 of 102 (5.9%) carriers of a duplication of at least 1 Mb (OR, 3.67; 95% CI, 1.29-8.54; P = .008) had an intellectual disability compared with 114 of 6819 (1.7%) in the Estonian cohort. The mean education attainment was 3.81 (P = 1.06e-04) among 248 (≥250 kb) deletion carriers and 3.69 (P = 5.024e-05) among 115 duplication carriers (≥1 Mb). Of the deletion carriers, 33.5% did not graduate from high school (OR, 1.48; 95% CI, 1.12-1.95; P = .005) and 39.1% of duplication carriers did not graduate high school (OR, 1.89; 95% CI, 1.27-2.8; P = 1.6e-03). Evidence for an association between rare CNVs and lower educational attainment was supported by analyses of cohorts of adults from Italy and the United States and adolescents from the United Kingdom. CONCLUSIONS AND RELEVANCE: Known pathogenic CNVs in unselected, but assumed to be healthy, adult populations may be associated with unrecognized clinical sequelae. Additionally, individually rare but collectively common intermediate-size CNVs may be negatively associated with educational attainment. Replication of these findings in additional population groups is warranted given the potential implications of this observation for genomics research, clinical care, and public health.

Commentary on "The Cognitive-Emotional Brain: From Interactions to Integration" by Luiz Pessoa - "On theory integration: Toward developing affective components within cognitive architectures"

In The Cognitive-Emotional Brain, Pessoa (2013) suggests that cognition and emotion should not be considered separately. We agree with this and argue that cognitive architectures can provide steady ground for this kind of theory integration and for investigating interactions among underlying cognitive processes. We briefly explore how affective components can be implemented and how neuroimaging measures can help validate models and influence theory development.

Polyphenol-rich foods in the Mediterranean diet are associated with better cognitive function in elderly subjects at high cardiovascular risk

Brain oxidative processes play a major role in age-related cognitive decline, thus consumption of antioxidant-rich foods might help preserve cognition. Our aim was to assess whether consumption of antioxidant-rich foods in the Mediterranean diet relates to cognitive function in the elderly. In asymptomatic subjects at high cardiovascular risk (n = 447; 52% women; age 55-80 y) enrolled in the PREDIMED study, a primary prevention dietary-intervention trial, we assessed food intake and cardiovascular risk profile, determined apolipoprotein E genotype, and used neuropsychological tests to evaluate cognitive function.We also measured urinary polyphenols as an objective biomarker of intake. Associations between energy-adjusted food consumption, urinary polyphenols, and cognitive scores were assessed by multiple linear regression models adjusted for potential confounders. Consumption of some foods was independently related to better cognitive function. The specific associations [regression coefficients (95% confidence intervals)] were: total olive oil with immediate verbal memory [0.755 (0.151-1.358)]; virgin olive oil and coffee with delayed verbal memory [0.163 (0.010-0.316) and 0.294 (0.055-0.534), respectively];walnuts with working memory [1.191 (0.061-2.322)]; and wine with Mini-Mental State Examination scores [0.252 (0.006-0.496)]. Urinary polyphenols were associated with better scores in immediate verbal memory [1.208 (0.236-2.180)]. Increased consumption of antioxidant-rich foods in general and of polyphenols in particular is associated with better cognitive performance in elderly subjects at high cardiovascular risk. The results reinforce the notion that Mediterranean diet components might counteract age-related cognitive decline.

Serum anticholinergic activity and postoperative cognitive dysfunction in elderly parients

BACKGROUND: Cerebral cholinergic transmission plays a key role in cognitive function, and anticholinergic drugs administered during the perioperative phase are a hypothetical cause of postoperative cognitive dysfunction (POCD). We hypothesized that a perioperative increase in serum anticholinergic activity (SAA) is associated with POCD in elderly patients. METHODS: Seventy-nine patients aged >65 years undergoing elective major surgery under stan- dardized general anesthesia (thiopental, sevoflurane, fentanyl, and atracurium) were investi- gated. Cognitive functions were assessed preoperatively and 7 days postoperatively using the extended version of the CERAD-Neuropsychological Assessment Battery. POCD was defined as a postoperative decline >1 z-score in at least 2 test variables. SAA was measured preop- eratively and 7 days postoperatively at the time of cognitive testing. Hodges-Lehmann median differences and their 95% confidence intervals were calculated for between-group comparisons. RESULTS: Of the patients who completed the study, 46% developed POCD. Patients with POCD were slightly older and less educated than patients without POCD. There were no relevant differences between patients with and without POCD regarding gender, demographically cor- rected baseline cognitive functions, and duration of anesthesia. There were no large differences between patients with and without POCD regarding SAA preoperatively (pmol/mL, median [inter- quartile range]/median difference [95% CI], P; 1.14 [0.72, 2.37] vs 1.13 [0.68, 1.68]/0.12 [−0.31, 0.57], P = 0.56), SAA 7 days postoperatively (1.32 [0.68, 2.59] vs 0.97 [0.65, 1.83]/0.25 [−0.26, 0.81], P = 0.37), or changes in SAA (0.08 [−0.50, 0.70] vs −0.02 [−0.53, 0.41]/0.1 [−0.31, 0.52], P = 0.62). There was no significant relationship between changes in SAA and changes in cognitive function (Spearman rank correlation coefficient preoperatively of 0.03 [95% CI, −0.21, 0.26] and postoperatively of −0.002 [95% CI, −0.24, 0.23]). CONCLUSIONS: In this panel of patients with low baseline SAA and clinically insignificant periopera- tive anticholinergic burden, although a relationship cannot be excluded in some patients, our analysis suggests that POCD is probably not a substantial consequence of anticholinergic medications admin- istered perioperatively but rather due to other mechanisms.

A multi-contrast MRI study of microstructural brain damage in patients with mild cognitive impairment.

OBJECTIVES: The aim of this study was to investigate pathological mechanisms underlying brain tissue alterations in mild cognitive impairment (MCI) using multi-contrast 3 T magnetic resonance imaging (MRI). METHODS: Forty-two MCI patients and 77 healthy controls (HC) underwent T1/T2* relaxometry as well as Magnetization Transfer (MT) MRI. Between-groups comparisons in MRI metrics were performed using permutation-based tests. Using MRI data, a generalized linear model (GLM) was computed to predict clinical performance and a support-vector machine (SVM) classification was used to classify MCI and HC subjects. RESULTS: Multi-parametric MRI data showed microstructural brain alterations in MCI patients vs HC that might be interpreted as: (i) a broad loss of myelin/cellular proteins and tissue microstructure in the hippocampus (p ≤ 0.01) and global white matter (p < 0.05); and (ii) iron accumulation in the pallidus nucleus (p ≤ 0.05). MRI metrics accurately predicted memory and executive performances in patients (p ≤ 0.005). SVM classification reached an accuracy of 75% to separate MCI and HC, and performed best using both volumes and T1/T2*/MT metrics. CONCLUSION: Multi-contrast MRI appears to be a promising approach to infer pathophysiological mechanisms leading to brain tissue alterations in MCI. Likewise, parametric MRI data provide powerful correlates of cognitive deficits and improve automatic disease classification based on morphometric features.

Structural Brain Connectivity in School-Age Preterm Infants Provides Evidence for Impaired Networks Relevant for Higher Order Cognitive Skills and Social Cognition.

Extreme prematurity and pregnancy conditions leading to intrauterine growth restriction (IUGR) affect thousands of newborns every year and increase their risk for poor higher order cognitive and social skills at school age. However, little is known about the brain structural basis of these disabilities. To compare the structural integrity of neural circuits between prematurely born controls and children born extreme preterm (EP) or with IUGR at school age, long-ranging and short-ranging connections were noninvasively mapped across cortical hemispheres by connection matrices derived from diffusion tensor tractography. Brain connectivity was modeled along fiber bundles connecting 83 brain regions by a weighted characterization of structural connectivity (SC). EP and IUGR subjects, when compared with controls, had decreased fractional anisotropy-weighted SC (FAw-SC) of cortico-basal ganglia-thalamo-cortical loop connections while cortico-cortical association connections showed both decreased and increased FAw-SC. FAw-SC strength of these connections was associated with poorer socio-cognitive performance in both EP and IUGR children.

Cognitive anatomy of the temporal lobe: Effect of personality in population with mild cognitive impairment & Functional specialization for memory systems in healthy individuals.

Résumé: L'impact de la maladie d'Alzheimer (MA) est dévastateur pour la vie quotidienne de la personne affectée, avec perte progressive de la mémoire et d'autres facultés cognitives jusqu'à la démence. Il n'existe toujours pas de traitement contre cette maladie et il y a aussi une grande incertitude sur le diagnostic des premiers stades de la MA. La signature anatomique de la MA, en particulier l'atrophie du lobe temporal moyen (LTM) mesurée avec la neuroimagerie, peut être utilisée comme un biomarqueur précoce, in vivo, des premiers stades de la MA. Toutefois, malgré le rôle évident du LMT dans les processus de la mémoire, nous savons que les modèles anatomiques prédictifs de la MA basés seulement sur des mesures d'atrophie du LTM n'expliquent pas tous les cas cliniques. Au cours de ma thèse, j'ai conduit trois projets pour comprendre l'anatomie et le fonctionnement du LMT dans (1) les processus de la maladie et dans (2) les processus de mémoire ainsi que (3) ceux de l'apprentissage. Je me suis intéressée à une population avec déficit cognitif léger (« Mild Cognitive Impairment », MCI), à risque pour la MA. Le but du premier projet était de tester l'hypothèse que des facteurs, autres que ceux cognitifs, tels que les traits de personnalité peuvent expliquer les différences interindividuelles dans le LTM. De plus, la diversité phénotypique des manifestations précliniques de la MA provient aussi d'une connaissance limitée des processus de mémoire et d'apprentissage dans le cerveau sain. L'objectif du deuxième projet porte sur l'investigation des sous-régions du LTM, et plus particulièrement de leur contribution dans différentes composantes de la mémoire de reconnaissance chez le sujet sain. Pour étudier cela, j'ai utilisé une nouvelle méthode multivariée ainsi que l'IRM à haute résolution pour tester la contribution de ces sous-régions dans les processus de familiarité (« ou Know ») et de remémoration (ou « Recollection »). Finalement, l'objectif du troisième projet était de tester la contribution du LTM en tant que système de mémoire dans l'apprentissage et l'interaction dynamique entre différents systèmes de mémoire durant l'apprentissage. Les résultats du premier projet montrent que, en plus du déficit cognitif observé dans une population avec MCI, les traits de personnalité peuvent expliquer les différences interindividuelles du LTM ; notamment avec une plus grande contribution du neuroticisme liée à une vulnérabilité au stress et à la dépression. Mon étude a permis d'identifier un pattern d'anormalité anatomique dans le LTM associé à la personnalité avec des mesures de volume et de diffusion moyenne du tissu. Ce pattern est caractérisé par une asymétrie droite-gauche du LTM et un gradient antéro-postérieur dans le LTM. J'ai interprété ce résultat par des propriétés tissulaires et neurochimiques différemment sensibles au stress. Les résultats de mon deuxième projet ont contribué au débat actuel sur la contribution des sous-régions du LTM dans les processus de familiarité et de remémoration. Utilisant une nouvelle méthode multivariée, les résultats supportent premièrement une dissociation des sous-régions associées aux différentes composantes de la mémoire. L'hippocampe est le plus associé à la mémoire de type remémoration et le cortex parahippocampique, à la mémoire de type familiarité. Deuxièmement, l'activation correspondant à la trace mnésique pour chaque type de mémoire est caractérisée par une distribution spatiale distincte. La représentation neuronale spécifique, « sparse-distributed», associée à la mémoire de remémoration dans l'hippocampe serait la meilleure manière d'encoder rapidement des souvenirs détaillés sans interférer les souvenirs précédemment stockés. Dans mon troisième projet, j'ai mis en place une tâche d'apprentissage en IRM fonctionnelle pour étudier les processus d'apprentissage d'associations probabilistes basé sur le feedback/récompense. Cette étude m'a permis de mettre en évidence le rôle du LTM dans l'apprentissage et l'interaction entre différents systèmes de mémoire comme la mémoire procédurale, perceptuelle ou d'amorçage et la mémoire de travail. Nous avons trouvé des activations dans le LTM correspondant à un processus de mémoire épisodique; les ganglions de la base (GB), à la mémoire procédurale et la récompense; le cortex occipito-temporal (OT), à la mémoire de représentation perceptive ou l'amorçage et le cortex préfrontal, à la mémoire de travail. Nous avons également observé que ces régions peuvent interagir; le type de relation entre le LTM et les GB a été interprété comme une compétition, ce qui a déjà été reporté dans des études récentes. De plus, avec un modèle dynamique causal, j'ai démontré l'existence d'une connectivité effective entre des régions. Elle se caractérise par une influence causale de type « top-down » venant de régions corticales associées avec des processus de plus haut niveau venant du cortex préfrontal sur des régions corticales plus primaires comme le OT cortex. Cette influence diminue au cours du de l'apprentissage; cela pourrait correspondre à un mécanisme de diminution de l'erreur de prédiction. Mon interprétation est que cela est à l'origine de la connaissance sémantique. J'ai également montré que les choix du sujet et l'activation cérébrale associée sont influencés par les traits de personnalité et des états affectifs négatifs. Les résultats de cette thèse m'ont amenée à proposer (1) un modèle expliquant les mécanismes possibles liés à l'influence de la personnalité sur le LTM dans une population avec MCI, (2) une dissociation des sous-régions du LTM dans différents types de mémoire et une représentation neuronale spécifique à ces régions. Cela pourrait être une piste pour résoudre les débats actuels sur la mémoire de reconnaissance. Finalement, (3) le LTM est aussi un système de mémoire impliqué dans l'apprentissage et qui peut interagir avec les GB par une compétition. Nous avons aussi mis en évidence une interaction dynamique de type « top -down » et « bottom-up » entre le cortex préfrontal et le cortex OT. En conclusion, les résultats peuvent donner des indices afin de mieux comprendre certains dysfonctionnements de la mémoire liés à l'âge et la maladie d'Alzheimer ainsi qu'à améliorer le développement de traitement. Abstract: The impact of Alzheimer's disease is devastating for the daily life of the affected patients, with progressive loss of memory and other cognitive skills until dementia. We still lack disease modifying treatment and there is also a great amount of uncertainty regarding the accuracy of diagnostic classification in the early stages of AD. The anatomical signature of AD, in particular the medial temporal lobe (MTL) atrophy measured with neuroimaging, can be used as an early in vivo biomarker in early stages of AD. However, despite the evident role of MTL in memory, we know that the derived predictive anatomical model based only on measures of brain atrophy in MTL does not explain all clinical cases. Throughout my thesis, I have conducted three projects to understand the anatomy and the functioning of MTL on (1) disease's progression, (2) memory process and (3) learning process. I was interested in a population with mild cognitive impairment (MCI), at risk for AD. The objective of the first project was to test the hypothesis that factors, other than the cognitive ones, such as the personality traits, can explain inter-individual differences in the MTL. Moreover, the phenotypic diversity in the manifestations of preclinical AD arises also from the limited knowledge of memory and learning processes in healthy brain. The objective of the second project concerns the investigation of sub-regions of the MTL, and more particularly their contributions in the different components of recognition memory in healthy subjects. To study that, I have used a new multivariate method as well as MRI at high resolution to test the contribution of those sub-regions in the processes of familiarity and recollection. Finally, the objective of the third project was to test the contribution of the MTL as a memory system in learning and the dynamic interaction between memory systems during learning. The results of the first project show that, beyond cognitive state of impairment observed in the population with MCI, the personality traits can explain the inter-individual differences in the MTL; notably with a higher contribution of neuroticism linked to proneness to stress and depression. My study has allowed identifying a pattern of anatomical abnormality in the MTL related to personality with measures of volume and mean diffusion of the tissue. That pattern is characterized by right-left asymmetry in MTL and an anterior to posterior gradient within MTL. I have interpreted that result by tissue and neurochemical properties differently sensitive to stress. Results of my second project have contributed to the actual debate on the contribution of MTL sub-regions in the processes of familiarity and recollection. Using a new multivariate method, the results support firstly a dissociation of the subregions associated with different memory components. The hippocampus was mostly associated with recollection and the surrounding parahippocampal cortex, with familiarity type of memory. Secondly, the activation corresponding to the mensic trace for each type of memory is characterized by a distinct spatial distribution. The specific neuronal representation, "sparse-distributed", associated with recollection in the hippocampus would be the best way to rapidly encode detailed memories without overwriting previously stored memories. In the third project, I have created a learning task with functional MRI to sudy the processes of learning of probabilistic associations based on feedback/reward. That study allowed me to highlight the role of the MTL in learning and the interaction between different memory systems such as the procedural memory, the perceptual memory or priming and the working memory. We have found activations in the MTL corresponding to a process of episodic memory; the basal ganglia (BG), to a procedural memory and reward; the occipito-temporal (OT) cortex, to a perceptive memory or priming and the prefrontal cortex, to working memory. We have also observed that those regions can interact; the relation type between the MTL and the BG has been interpreted as a competition. In addition, with a dynamic causal model, I have demonstrated a "top-down" influence from cortical regions associated with high level cortical area such as the prefrontal cortex on lower level cortical regions such as the OT cortex. That influence decreases during learning; that could correspond to a mechanism linked to a diminution of prediction error. My interpretation is that this is at the origin of the semantic knowledge. I have also shown that the subject's choice and the associated brain activation are influenced by personality traits and negative affects. Overall results of this thesis have brought me to propose (1) a model explaining the possible mechanism linked to the influence of personality on the MTL in a population with MCI, (2) a dissociation of MTL sub-regions in different memory types and a neuronal representation specific to each region. This could be a cue to resolve the actual debates on recognition memory. Finally, (3) the MTL is also a system involved in learning and that can interact with the BG by a competition. We have also shown a dynamic interaction of « top -down » and « bottom-up » types between the pre-frontal cortex and the OT cortex. In conclusion, the results could give cues to better understand some memory dysfunctions in aging and Alzheimer's disease and to improve development of treatment.