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International audience; The aging process does not progress at the same speed between individuals (Hertzog, Kramer, Wilson, & Lindenberger,2008). The following two categories of factors moderate the speed of aging and explain a large part of the variance in the cognitive performance of individuals throughout the life span: genetic factors and lifestyle factors. Genetic factors are related to genetic polymorphisms that can influence cognitive phenotypes. Lifestyle factors notably include the amount of physical activity (PA) practiced every week throughout a long period (e.g., 1 year) and the dietary habits. This chapter aimsto specify the relationships among the following four variables: aging, inhibitory control, the genetic polymorphism of the brain-derived neurotrophic factor (BDNF) gene located at codon 66, and PA.In the second and following section, we focus on inhibitory control and show its crucial role in cognition and daily living. In the third section, we discuss on the unity and diversity of inhibitory processes. In the fourth section, we presentthe two main categories of effortful inhibitory control and their brain substrates. In the fifth section, we address the deleterious effect of aging on this important executive function. In the sixth section, we explain the role of neurotrophins, and more particularly the brain-derived neurotrophic factor (BDNF), in brain plasticity and brain health, and present the gene that affects its trafficking and secretion. In the seventh and eighth parts, we review the role of the genetic polymorphism of this gene in cognition during aging. Finally, in the ninth section, we examine the moderating role of physicalactivity and eating behaviors in the relationship between BDNF polymorphism and cognitive aging.

International audience; In the present study, participants played a modified ultimatum game simulating a situation of inclusion/exclusion, in which either the participant or a rival could be selected to play as the responder. This selection was made either randomly by a computer (i.e. random pairing mode) or by the proposer (i.e. choice mode), based on physical appearance. Being chosen by the proposer triggered positive reciprocal behavior in participants, who accepted unfair offers more frequently than when they had been selected by the computer. Independently of selection mode, greater P200 amplitudes were found when participants received fair offers than when they received unfair offers and when unfair shares were offered to their rivals rather than to them, suggesting that receiving fair offers or observing a rival's misfortune was rewarding for participants. While participants generally showed more interest in the offers they themselves received (i.e. greater P300 responses to these offers), observing their rivals receive fair shares after the latter had been chosen by the proposer triggered an increase in P300 amplitude likely to ref lect a feeling of envy. This study provides new insights into both the cognitive and affective processes underpinning economic decision making in a context of social inclusion/exclusion.

The present study aimed to examine the effects of chronological age and cardiorespiratory fitness (CRF) on cognitive performance and prefrontal cortex activity, and to test the compensation-related utilization of neural circuits hypothesis (CRUNCH). A total of 19 young adults (18&ndash, 22 years) and 37 older ones (60&ndash, 77 years) with a high or low CRF level were recruited to perform a working memory updating task under three different cognitive load conditions. Prefrontal cortex hemodynamic responses were continuously recorded using functional near-infrared spectroscopy, and behavioral performances and perceived difficulty were measured. Results showed that chronological age had deleterious effects on both cognitive performance and prefrontal cortex activation under a higher cognitive load. In older adults, however, higher levels of CRF were related to increased bilateral prefrontal cortex activation patterns that allowed them to sustain better cognitive performances, especially under the highest cognitive load. These results are discussed in the light of the neurocognitive CRUNCH model.

International audience; Introduction. Cognitive reserve (CR) was proposed to explain how individual differences in brain function help to cope with the effects of normal aging and neurodegenerative diseases. Education, professional solicitations, and engagement in leisure and physical activities across the lifetime are considered as major determinants of this reserve. Method. Using multiple linear regression analyses, we tested separately in healthy elderly and Parkinson’s disease (PD) populations to what extent cognitive performance in several domains was explained by (a) any of these four environmental lifespan variables; (b) demographic and clinical variables (age, gender, depression score, and, for the PD group, duration of disease and dopaminergic drugs). We also tested for an interaction, if any, between these lifespan variables and brain pathology indexed by global atrophy measured from high-resolution anatomical magnetic resonance imaging. Results. Age was negatively associated with cognitive performance in the PD group. In healthy elderly participants, we observed significant positive associations between cognitive performance and (a) education, (b) leisure activities, and (c) professional solicitation (decisional latitude). Furthermore, participants with greater brain atrophy benefited more from CR. In PD patients, education and professional solicitations contributed to cognitive performance but to a lesser extent than in controls. CR factors modulated the relationship between cognition and brain atrophy only in patients with a slight or moderate brain atrophy. Conclusions. Education is the CR factor that contributed the most to late cognitive functioning in both groups, closely followed by leisure activity in normal aging and professional solicitations in PD. Our results also provide evidence suggesting that the effects of CR does not express similarly in normal aging and PD. From a broader perspective, these results seem to indicate that CR factors the most consistently practiced across lifespan (education and professional solicitation) are those that are the more strongly associated to late cognitive efficiency.

The objective of this study was to examine age-related effects on behavioral performance and metabolic activity of the prefrontal cortex (PFC) in a dual-task paradigm involving fine-motor control and executive-function control. Thirty-one adults (20 ± 1.1 years) and 33 older adults (70.7 ± 5.1 years) performed, separately and then concurrently, a modified Fitts task on targets of different sizes (Index of Difficulty: ID = 3; 4; 5 bits) and the random number generation task (RNG). Movement time (MT) and count score (CS) were the dependent variables for the modified Fitts task and the RNG task, respectively. Relative changes in concentrations of oxyhemoglobin [HbO2] and deoxyhemoglobin [HHb] were recorded continuously on the left and right PFCs, with near-infrared spectroscopy (Oxymon MkIII-Artinis) with an acquisition rate of 10 Hz. Our results showed large motor dual-task cost in seniors compared to young adults. Regarding hemodynamic activity, we have observed a prominent activation of the PFC in the young adults compared to the seniors during the dual-task condition.

International audience; The aim of the present study was to provide descriptive dietary patterns of home-living older adults, and to examine their association with sociodemographic and ‘diet-related’ variables, and health and psychological factors. Dietary patterns were analyzed using separately cluster analysis for men (N = 151, Mage = 72.72, SD = 8.80, range = 56-97) and women (N = 251, Mage = 76.74, SD = 9.95, range = 55-97) in 402 older adults aged 55 years and over. Cluster analyses showed four distinct dietary profiles for each gender. In older men, the four distinct dietary clusters were associated with any differences in sociodemographic and ‘diet-related’ variables, cognitive function, and health and psychological factors. Likewise, in older women, the four distinct dietary clusters were associated with any differences in sociodemographic and ‘diet-related' variables’. However in older women, results showed that the cluster 1 “high fish-fruit-vegetable” was associated with a better cognitive function, a better self-rated health and no depressive symptoms, whereas cluster 3 “moderate ready meals” was associated with cognitive decline, slight depression, and poor perceived health. Results emphasize the interest to take into consideration health and psychological factors associated with dietary patterns to better target the vulnerability of individuals and enable an effective prevention.

International audience; The cognitive neuroscience of aging is a growing and stimulating research area. The development of neuroimaging techniques in the past two decades has considerably increased our understanding of the brain mechanisms that might underlie cognitive performance and resulting changes due to normal aging. Beside traditional metabolic neuroimaging techniques, such as Positron Emission Tomography and functional Magnetic Resonance Imaging, near infrared spectroscopy (NIRS), an optical imaging technique allowing to monitor real-time cerebral blood oxygenation, has gained recent interest in this field. The aim of the present review paper, after briefly presenting the NIRS technique, is to review and to summarize the recent results of neuroimaging studies using this technique in the field of cognitive aging. The reviewed literature shows that, despite low spatial resolution and cerebral depth penetration, this technique provides consistent findings on the reduced hemodynamic activity as a function of chronological age, mainly in the prefrontal cortex. Important moderators of brain hemodynamics, such as cognitive load, subjects’ characteristics and experimental conditions, for which the NIRS technique is sensitive, are discussed. Strengths and weaknesses of functional NIRS in the field of cognitive aging are presented and finally, novel perspectives of research are proposed.

International audience; It is well-known that processing speed and executive functions decline with advancing age. However, physical activity (PA) has a positive impact on cognitive performances in aging, specifically for inhibition. Less is known concerning intraindividual variability (iiV) in reaction times. This study aims to investigate the influence of PA and sex differences on iiV in inhibitory performance during aging. Healthy adults were divided into active and sedentary groups according to PA level. To analyse iiV in reaction times, individual mean, standard deviation and the ex-Gaussian parameters were considered. An interaction between activity level and sex was revealed, sedentary females being slower and more variable than sedentary men. No sex differences were found in the active groups. These results indicate that the negative impact of sedentariness on cognitive performance in older age is stronger for females. The present findings underline the need to consider sex differences in active aging approaches.

International audience; The aims of this study were to examine the effects of aerobic exercise on measures of executive performance and their relationships with changes in cardiorespiratory fitness, cardiac vagal control (heart rate variability) and psychological variables. Thirty-six sedentary seniors aged 60–75 years were randomly assigned to a swimming and aquaerobics program or a stretching program two times a week for 21 weeks. Executive functions (inhibition, updating of working memory and cognitive flexibility) and cardiorespiratory fitness (estimated VO2max) were assessed at the start, after 10 weeks of program and at the end of the program. Resting HRV and measures of psychological outcomes (depression, self-efficacy, decisional balance) were obtained at the start and at the end of the program. Participants of both groups significantly improved their VO2max level, their psychological state and their performance for the 2-back task. Only the participants in the aquaerobics group significantly improved their vagally-mediated HRV and their performance for the Stroop test and the verbal running-span test at the end of the program. Only improvements in cardiac vagal control and in inhibition were shown to be functionally related. These results are discussed in line with the model of neurovisceral integration.

The present study investigated the extent to which the impact of motor difficulty on the acquisition of a computer task varies as a function of age. Fourteen young and 14 older participants performed 352 sequences of 10 serial pointing movements with a wireless pen on a digitiser tablet. A conditional probabilistic structure governed the succession of target keys to be pointed at on a virtual keyboard. Detecting and learning with practice how to use this probabilistic structure was expected to allow the participants to anticipate the location of the targets, and thus to improve pointing performance in terms of speed, accuracy, and trajectory rectitude. Motor difficulty was manipulated through the size of the targets to be pointed at. Results showed that for older participants, but not for younger ones, motor difficulty had a detrimental effect on their ability to learn the probabilistic structure. This finding suggests that decreasing the target size provides complex detrimental influence on the performance, affecting the efficiency of both the motor and cognitive processes involved in the task, especially for the elderly.

International audience; This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV) and on executive performance in older people. Twenty-four sedentary men and women aged 65–78 years were randomly assigned to an aerobic exercise program or a stretching program three times a week for 12 weeks. Resting HRV was measured in time and frequency domains in each participant before and after the 12-week programs. Executive performance was measured with the Wisconsin card sorting test (WCST). Significant group–session interactions emerged for the standard deviation of normal beat-to-beat (R–R) intervals, the root-mean-square of successive R–R, and high frequency power. Only the aerobic training group increased vagal-mediated HRV parameters. Moreover, only the participants in the aerobic training group improved their performance on the WCST. These results highlight the role of aerobic exercise as an important cardiac and brain protective factor, and suggest a direct link between exercise, HRV, and cognition in the aged population.

Objectives: To study the effects of physical stimulation based on walking exercises, equilibrium and endurance on cognitive function and walking efficiency in patients with dementia. Methods: Randomized controlled trial including 31 subjects suffering from dementia (age: 81.8 ± 5.3 years). The intervention group (n = 16) benefited from a 15-week physical activity programme involving three 1-hour sessions per week. The control group (n = 15) did not practice any physical activities. Before and after rehabilitation, all subjects were evaluated with the Rapid Evaluation of Cognitive Functions test (ERFC French version) and walking analysis. Results: After the 15 weeks of rehabilitation, the subjects from the intervention group improved their overall ERFC score (p < 0.01), while those in the control group decreased their overall ERFC score. Interactions were also observed between walking parameters and groups (p < 0.01); the intervention group improved walking capacities through heightened walking speed, stride length and a reduction in double limb support time. Lastly, the subjects from the control group presented a reduction in both walking speed and stride length. Conclusion: This study shows that a physical activity programme can slow cognitive decline and improve quality of walking in elderly persons suffering from dementia.

Le vieillissement de la population est un phenomene majeur pour notre societe. Au niveau individuel, le vieillissement se caracterise notamment par un declin de la vitesse et de l’efficacite des processus cognitifs et sensori-moteurs. Cependant la dynamique du vieillissement n’est pas identique pour tous les individus et certains facteurs, lies au mode de vie, sont susceptibles de moduler ses effets. Parmi ces facteurs, la pratique reguliere d’activite physique fait aujourd’hui l’objet d’un travail de recherche croissant. Les travaux dans ce domaine montrent qu’elle peut etre un puissant facteur de maintien de la vitalite cognitive, essentielle a l’autonomie et a la qualite de vie des personnes âgees. Cet article se propose de faire le point sur les connaissances actuelles dans ce domaine de recherche. A travers une analyse des questions posees et des methodologies utilisees pour y repondre, nous montrerons que la relation entre activite physique et vieillissement cognitif semble etre aujourd’hui etablie. Cette relation est toutefois dependante de certains facteurs, comme la nature des tâches utilisees ou les caracteristiques des individus (âge, aptitude physique). Les principaux modeles theoriques elabores pour expliquer cette relation seront finalement presentes, nous amenant a proposer certaines perspectives de recherche.

International audience; Background:The brain-derived neurotrophic factor (BDNF) concentration is highest in the hippocampus comparedwith that in other brain structures and affects episodic memory, a cognitive function that is impaired in olderadults. According to the neurotrophic hypothesis, BDNF released during physical activity enhances brain plasticity andconsequently brain health. However, even if the physical activity level is involved in the secretion of neurotrophin, thisprotein is also under the control of a specific gene. The aim of the present study was to examine the effect of theinteraction between physical activity and BDNF Val66Met(rs6265), a genetic polymorphism, on episodic memory.Methods:Two hundred and five volunteers aged 55 and older with a Mini Mental State Examination score≥24participated in this study. Four groups of participants were established according to their physical activity level andpolymorphism BDNF profile (Active Val homozygous, Inactive Val homozygous, Active Met carriers, Inactive Met carriers).Episodic memory was evaluated based on the delayed recall of the Logical Memory test of the MEM III battery.Results:As expected, the physical activity level interacted with BDNF polymorphism to affect episodic memoryperformance (p< .05). The active Val homozygous participants significantly outperformed the active Met carriers andinactive Val homozygous participants.Conclusion:This study clearly demonstrates an interaction between physical activity andBDNF Val66Metpolymorphismthat affects episodic memory in the elderly and confirms that physical activity contributes to the neurotrophic mechanismimplicated in cognitive health. The interaction shows that only participants with Val/Val polymorphism benefited fromphysical activity

International audience; Falls represent a major cause of burden and death in older adults. The MACVIA-LR (fighting chronic diseases for active and healthy ageing in Languedoc-Roussillon) falls initiative is a cross-cutting Living Lab based on the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) at the regional level. It covers all action plans (A1, A2, A3, B3, C2 and D4) of the EIP on AHA. The Living Lab will: (i) raise awareness, (ii) drive attitude change with respect to falls and falls prevention and (iii) improve access to information on falls prevention. It aims to reduce fall-related hospitalisations by 30% in 2020 in the région Languedoc-Roussillon (LR). It includes: (i) a falls prevention clinic for the assessment of subjects (with a falls risk) in the two teaching hospitals of Montpellier and Nîmes, (ii) the Regional Ageing Institute (CARSAT-LR), (iii) the Low Vision Institute of Nîmes, (iv) the Lattes Social Welfare Centre, (v) the home automation Institut méditerranéen des métiers de longévité, (vi) teaching, training and coaching as well as (vii) industrial partnership. Two care pathways have been developed (stroke and falls) and are being applied to remote rural areas of the région. The MACVIA-falls prevention initiative is an output of the EIP on AHA.

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International audience; The purposes of this study were to determine the impact of physical activity on three different executive functions (shifting, inhibition, and updating) and to examine whether cardiovascular fitness was a good mediator of the positive link(s) between these variables. Sixty-three young adults (18–28 years), 30 young-old adults (60–70 years) and 30 old adults (71–81 years) were divided into physically active and sedentary groups according to physical activity level (assessed from an accelerometer and the Historical Leisure Activity Questionnaire). Cardiovascular fitness was assessed by VO2max from the Rockport 1 mile. Each executive function was assessed through three different experimental tasks. ANCOVAs revealed that the effect of physical activity level was specific to the old adults and significant for inhibition, but not for updating and shifting. Mediation analysis showed that this positive effect in the old adults group was mediated by cardiovascular fitness level. The present findings highlight the positive linkages among physical activity, cardiovascular fitness, and inhibition in aging.

International audience; The processing-speed theory and the prefrontal-executive theory are competing theories of cognitive aging. Here we used a theoretically and methodologically-driven framework to investigate the relationships among measures classically used to assess these two theoretical constructs. Twenty-eight young adults (18–32 years) and 39 healthy older adults (65–80 years) performed a battery of nine neuropsychological and experimental tasks assessing three executive function (EF) components: Inhibition, Updating, and Shifting. Rate of information processing was evaluated via three different experimental and psychometric tests. Partial correlations analyses suggested that 2-Choice Reaction Time (CRT) performance is a more pure measure of processing speed than Digit Symbol Substitution Test (DSST) performance in the elderly. Hierarchical regression analyses showed that, although measures of processing speed and EF components share mutual variance, each measure was independently affected by chronological age. The unique adverse effect of age was more important for processing speed than for EF. The processing-speed theory and the prefrontal-executive theory of cognitive aging were shown not to be mutually exclusive but share mutual variance. This implies the need to control for their mutual relationship before examining their unique potential role in the explanation of age-related cognitive declines. Caution has still to be taken concerning the tasks used to evaluate these theoretical constructs.

International audience; Prospective motor learning (PML) can be defined as learning an action to be performed in the future. The privileged retrieval mechanism behind this delayed motor performance remains unknown. From a motor control and learning perspective, we may conceive of two forms of retrieval: a stimulus- and an intention-based control. Retrieval from intention-based control is based on the anticipation of intended sensory effects related to an action in order to select and control the appropriate motor procedure (i.e., the ideomotor mechanism). In contrast, in a stimulus-based control a connection between stimuli-features and their related action-features is stored in the memory and serves as the retrieval mechanism. In this view, action retrieval from external stimuli is based on the detection of events in the environment to perform the intended behaviour (i.e., the sensorimotor mechanism). In this study, we report an advantage in the action retrieval for participants who use an intention-based mode of control in comparison to a stimulus-based control. Furthermore, a control task reveals that the intention-based advantage is specific to PML. Our findings show that PML is benefited by mental anticipation of a sensory effect that is efficiently processed through an ideomotor mechanism to fulfil delayed motor intentions.

International audience; Objectif.-Le but de cette étude était d'examiner l'effet d'un programme d'activités physiques sur la stabilité et le contrôle attentionnel de la posture lors de la réalisation concomitante d'une tâche cognitive attentionnelle chez des personnes âgées en perte d'autonomie. Méthode.-Douze personnes âgées (M = 81,4 ± 9 ans), institutionnalisées en structure gériatrique ont participé à un programme d'activités physiques de type posture-équilibration-motricité (PEM) pendant 12 semaines à raison de deux séances d'une heure par semaine. Les paramètres stabilométriques de surface et de longueur du trajet parcouru par le centre de pression plantaire (CPP), les yeux ouverts (YO) et les yeux fermés (YF), en condition simple-tâche et en condition double-tâche sur sol dur ont été analysés avant et après le programme d'entraînement. En condition double-tâche, les sujets effectuaient, lors de l'évaluation stabilométrique, une tâche cognitive attentionnelle de génération de chiffres aléatoires. Résultats.-Les principaux résultats ont révélé que seule la longueur du trajet parcouru par le CPP était plus importante en condition doubletâche qu'en condition simple-tâche (p = 0,05). Lors de l'évaluation initiale, la performance à la tâche cognitive était significativement moins bonne en condition double-tâche (debout) qu'en condition simple-tâche (assis), seulement dans la modalité YF mais pas dans la modalité YO (p < 0,05). Toutefois, à l'issue du programme d'entraînement, les performances à la tâche cognitive ne se différenciaient plus (n.s.) pour les deux conditions assis YF et debout YF. Conclusion.-L'entraînement a permis d'améliorer la capacité des sujets à réaliser une tâche mentale attentionnelle tout en maintenant un équilibre correct, notamment les yeux fermés. Bien que les performances stabilométriques semblaient moins bonnes en condition double-tâche qu'en condition simple-tâche, ces résultats pourraient être interprétés comme une amélioration, suite au programme d'entraînement, du contrôle attentionnel du maintien de la posture. Les limites méthodologiques de cette étude sont ensuite discutées.

Using a computer-simulated anticipation-coincidence task, the main aim of the study was to examine the effect of the type of instruction on learning a temporal pattern. For this task, participants must learn to anticipate the appropriate time to launch a projectile to hit a moving target. The experiment involved three instructional conditions. In the Explicit-rule Discover Instruction Condition participants were informed that target speed could change from trial to trial and that change is controlled by a regular pattern. Their task was then to search, to identify, and to use such pattern to enhance their anticipation. In the Explicit-Informative Instruction Condition, participants were, however, allowed before practice to examine attentively the regular pattern. Participants were also explicitly urged to use the pattern they observed to ensure a better interception of the target. Finally, in the Implicit Instruction Condition, participants were only informed that their task was to hit, or at least, to place the projectile as near as possible to the target. No additional information was provided about the target's behaviour. Analysis indicated that learning the temporal pattern was more important in Implicit than in Explicit-rule Discover Instruction Condition. However, the Explicit-Informative Instruction Condition produced unambiguously the highest learning. Overall, the study highlights the role of information over guidance in the understanding of the effect of the instructions on learning. Finally, we discussed the implications of these results on the comprehension of the variability of the effects of the instruction on learning.

International audience; A large number of epidemiological, cross-sectional and interventional studies present a body of convincing evidences for a prophylactic effect of the regular practice of physical activity on seniors’ brain and cognitive health. Three meta-analyses, gathering data from about 50 random control trials published from 1966 to 2009, clearly show a causal relationship between chronic physical exercise and cognitive performances of elderly, and that the size of this effect is moderate to large. Several cognitive functions such as information processing speed, executive functions and declarative memory seemed to function more efficiently following a six-month program combining 45 minutes of moderate- to high-intensity aerobic exercises (brisk walking, jogging) and resistance exercise at least three times a week. Different neurophysiological mechanisms involving neurotrophic factors released during exercise and linked to brain plasticity could explain and underpin this phenomenon. The relationship between cardiorespiratory or motor fitness and brain or cognitive health seems to be moderated by several individual factors closely related with the lifestyles of elderly (food diet, cognitive reserve accumulated throughout life) and their genetic inheritance (polymorphisms of apolipoprotein E, catechol-O-methyltransferase and brain-derived neurotrophic factor genes). Although the existence and the scientific and clinical interest of the effect of chronic exercise on brain and cognitive health were clearly established, social, health and exercise psychologists have to find methods to motivate sedentary older adults to start practicing regular physical activity and maintain this lifestyle as long as possible. Research indicates that theory-based interventions successfully influence adherence to physical activity. Two theoretical frameworks seem promising for that purpose: the theory of planned behavior and the transtheoretical model. Finally, several important theoretical and applied questions remain unanswered and need to be addressed in the future; for instance the efficacy of chronic exercise in preventing, delaying and/or slowing several brain neuropathologies such as Alzheimer’s or Parkinson’s diseases, strokes, or multiple sclerosis.; De nombreuses études épidémiologiques, transversales et interventionnelles présentent un faisceau d’arguments convaincants en faveur d’un effet prophylactique de la pratique régulière d’une activité physique sur la santé cérébrale et cognitive des seniors. Trois méta-analyses, rassemblant les données d’une cinquantaine d’essais contrôlés randomisés, montrent qu’il existe bien une relation de cause à effet entre l’exercice physique chronique et les performances cognitives des personnes âgées, et que l’amplitude de l’effet est faible à modérée. Différentes fonctions cognitives telles que la vitesse de traitement de l’information, les fonctions exécutives ou la mémoire déclarative semblent fonctionner de manière plus efficiente sous l’effet d’un programme de 6 mois combinant 45 minutes d’exercices physiques aérobies d’intensité modérée à élevée (marche soutenue, jogging) et d’exercices de musculation trois fois par semaine ou plus. Plusieurs mécanismes neurophysiologiques, impliquant différents facteurs neurotrophiques libérés au cours de l’exercice et augmentant la plasticité cérébrale, pourraient expliquer ce phénomène. Enfin, la relation entre la santé cardio-respiratoire et la santé cérébrale ou cognitive semble être modérée par différents facteurs individuels en lien avec les habitudes de vie des seniors (régime alimentaire, réserve cognitive accumulée au cours de la vie) ou leur patrimoine génétique (polymorphismes des gènes de l’apolipoprotéine E, de la catéchol-O-méthyltransférase et du facteur neurotrophique dérivé du cerveau).

A motor task that requires fine control of upper limb movements and a cognitive task that requires executive processing—first performing them separately and then concurrently—was performed by 18 young and 18 older adults. The motor task required participants to tap alternatively on two targets, the sizes of which varied systematically. The cognitive task required participants to generate a series of random numbers at fixed production rates. Participants' performance on the motor task decreased slightly from single- to concurrent-task condition, and the dual-task cost was age-independent. Older adults showed large cognitive dual-task costs as motor-control demands increased. Younger adults' cognitive performance was not affected by concurrent task demands. These results are discussed in light of the permeation model developed by Baltes and Lindenberger (1997). Practical implications and educational recommendations are presented.

Using continuous-wave near-infrared spectroscopy (NIRS), this study compared three different methods, namely the slope method (SM), the amplitude method (AM), and the area under the curve (AUC) method to determine the variations of intramuscular oxygenation level as a function of workload. Ten right-handed subjects (22+/-4 years) performed one isometric contraction at each of three different workloads (30 %, 50 % and 90 % of maximal voluntary strength) during a period of twenty seconds. Changes in oxyhemoglobin (delta[HbO(2)]) and deoxyhemoglobin (delta[HHb]) concentrations in the superficial flexor of fingers were recorded using continuous-wave NIRS. The results showed a strong consistency between the three methods, with standardized Cronbach alphas of 0.87 for delta[HHb] and 0.95 for delta[HbO(2)]. No significant differences between the three methods were observed concerning delta[HHb] as a function of workload. However, only the SM showed sufficient sensitivity to detect a significant decrease in delta[HbO(2)] between 30 % and 50 % of workload (p