Description of routes in people with intellectual disability

The ability to describe routes was assessed in participants with intellectual disability (ID) and participants without ID matched on chronological age (CA) or on mental age (MA). In two experiments, participants learned a route through a virtual environment until they reached a learning criterion. Then, they were asked to externalise their spatial knowledge in a verbal description task, a landmark recognition task or a map completion task. Results revealed that participants with ID mainly described the route as a succession of actions (“turn left”) while participants in the CA group prescribed actions referring to a landmark (“turn left at the swing”). Yet, results from the other tasks showed that individuals with ID had good landmark knowledge of the environment

Different aspects of emotional processes in apathy: Application of the French translated dimensional apathy scale

Apathy is a behavioural symptom that occurs in neuropsychiatric, neurological and neurodegenerative disease. It is defined as a lack of motivation and/or a quantitative reduction of goal-directed behaviour. Levy and Dubois Cerebral Cortex, 16(7), 916–928 (2006) proposed a triadic substructure of apathy and similar subtypes can be assessed using the Dimensional Apathy Scale (DAS), via the Executive, Emotional and Initiation subscales. The aim of this study was to translate the DAS in to French (f-DAS), examine its psychometric properties and the substructure of apathy using Confirmatory Factor Analysis (CFA). The results showed an acceptable internal consistency reliability of the f-DAS and a similar relationship to depression as in the original DAS development study. The CFA supported a triadic dimensional substructure of the f-DAS, similar to the original DAS but suggested a more complex substructure, specifically, two further processes of the Emotional apathy dimension relating to “Social Emotional” and “Individual Emotional” aspects of demotivation. To conclude, the f-DAS is a robust and reliable tool for assessing multidimensional apathy. Further research should explore the utility of the f-DAS in patients with neuropsychiatric diseases in view of social emotional aspects in apathy

Multifractal and entropy analysis of resting-state electroencephalography reveals spatial organization in local dynamic functional connectivity

Functional connectivity of the brain fluctuates even in resting-state condition. It has been reported recently that fluctuations of global functional network topology and those of individual connections between brain regions expressed multifractal scaling. To expand on these findings, in this study we investigated if multifractality was indeed an inherent property of dynamic functional connectivity (DFC) on the regional level as well. Furthermore, we explored if local DFC showed region-specific differences in its multifractal and entropy-related features. DFC analyses were performed on 62-channel, resting-state electroencephalography recordings of twelve young, healthy subjects. Surrogate data testing verified the true multifractal nature of regional DFC that could be attributed to the presumed nonlinear nature of the underlying processes. Moreover, we found a characteristic spatial distribution of local connectivity dynamics, in that frontal and occipital regions showed stronger long-range correlation and higher degree of multifractality, whereas the highest values of entropy were found over the central and temporal regions. The revealed topology reflected well the underlying resting-state network organization of the brain. The presented results and the proposed analysis framework could improve our understanding on how resting-state brain activity is spatio-temporally organized and may provide potential biomarkers for future clinical research

Environmental enrichment reduces signs of boredom in caged mink

Animals housed in impoverished cages are often labelled 'bored'. They have also been called 'apathetic' or 'depressed', particularly when profoundly inactive. However, these terms are rarely operationally defined and validated. As a negative state caused by under-stimulation, boredom should increase interest in stimuli of all kinds. Apathy (lack of interest), by contrast, should manifest as decreased interest in all stimuli, while anhedonia (loss of pleasure, a depressive symptom) should specifically decrease interest in normally rewarding stimuli. We tested the hypotheses that mink, a model carnivore, experience more boredom, depression-like apathy, or anhedonia in non-enriched (NE) cages than in complex, enriched (E) cages. We exposed 29 subjects (13 E, 16 NE) to ten stimuli categorized a priori as aversive (e.g. air puffs), rewarding (e.g. evoking chasing) or ambiguous/neutral (e.g. candles). Interest in stimuli was assessed via latencies to contact, contact durations, and durations oriented to stimuli. NE mink contacted all stimuli faster (P = 0.003) than E mink, and spent longer oriented to/in contact with them, albeit only significantly so for ambiguous ones (treatment*type P<0.013). With stimulus category removed from statistical models, interest in all stimuli was consistently higher among NE mink (P<0.0001 for all measures). NE mink also consumed more food rewards (P = 0.037). Finally, we investigated whether lying down while awake and stereotypic behaviour (both increased by NE housing) predicted these responses. Lying awake positively co-varied with certain measures of increased exploration. In contrast, stereotypic 'scrabbling' or locomotion (e.g. pacing) did not. Overall, NE mink showed no evidence of apathy or depression, but instead a heightened investigation of diverse stimuli consistent with boredom. This state was potentially indicated by spending much time lying still but awake (although this result requires replication). Boredom can thus be operationalized and assessed empirically in non-human animals. It can also be reduced by environmental enrichment

Route knowledge and configural knowledge in typical and atypical development: a comparison of sparse and rich environments

Background: Individuals with Down syndrome (DS) and individuals with Williams syndrome (WS) have poor navigation skills, which impact their potential to become independent. Two aspects of navigation were investigated in these groups, using virtual environments (VE): route knowledge (the ability to learn the way from A to B by following a fixed sequence of turns) and configural knowledge (knowledge of the spatial relationships between places within an environment). Methods: Typically developing (TD) children aged 5 to 11 years (N = 93), individuals with DS (N = 29) and individuals with WS (N = 20) were presented with a sparse and a rich VE grid maze. Within each maze, participants were asked to learn a route from A to B and a route from A to C before being asked to find a novel shortcut from B to C. Results: Performance was broadly similar across sparse and rich mazes. The majority of participants were able to learn novel routes, with poorest performance in the DS group, but the ability to find a shortcut, our measure of configural knowledge, was limited for all three groups. That is, 59 % TD participants successfully found a shortcut, compared to 10 % participants with DS and 35 % participants with WS. Differences in the underlying mechanisms associated with route knowledge and configural knowledge and in the developmental trajectories of performance across groups were observed. Only the TD participants walked a shorter distance in the last shortcut trial compared to the first, indicative of increased configural knowledge across trials. The DS group often used an alternative strategy to get from B to C, summing the two taught routes together. Conclusions: Our findings demonstrate impaired configural knowledge in DS and in WS, with the strongest deficit in DS. This suggests that these groups rely on a rigid route knowledge based method for navigating and as a result are likely to get lost easily. Route knowledge was also impaired in both DS and WS groups and was related to different underlying processes across all three groups. These are discussed with reference to limitations in attention and/or visuo-spatial processing in the atypical groups

Evolution temporelle d'un amorçage hémisphérique dans une situation double-tâche

Summary : Temporal evolution of hemispheric priming in a dual-task situation. The heuristic importance of dual-task paradigms is easily demonstrated in the field of hemispheric asymmetries. Dual-task paradigms have contributed to the evolution of static and dynamic models, particularly by taking into account contextual aspects as potential determinants of lateral effects. In this research area, the concept of priming refers to the processes by which an hemisphere is activated prior to the carrying out of a task. This priming effect can be forced by the execution of a secondary lateralized task. We developed a situation in which the main task was a divided-visual-field tachistoscopic matching test. According to a random-controlled situation, subjects were instructed to say whether the two stimuli were « the same » or « different » before, concurrently or after (with an inter-task interval of 1,5, 2,5 or 4 seconds) an activating task. For this latter task, the subjects were asked to beat a complex rhythm by hitting in a loop on a sensitive board. As expected, the results showed a significant increase in the number of correct responses in the activated hemisphere. Moreover, an optimum was found when the task was performed concurrently or with an interval of 1,5 second after the end of the priming task. The priming process seems to be a temporal function characterized by an immediate increase and by a later and progressive decrease in the resources of the hemisphere involved. These hemisphere-specific activation paradigms are mainly used to produce an inter-hemispheric imbalance in normal or pathological subjects. Through an inter-hemispheric imbalance it is possible to access details of hemispheric co-operation for information processing or to induce new cognitive capacities in a non-damaged hemisphere. Our results suggest the importance of optimizing these paradigms by taking into account the temporal evolution of the brain activation. Key words : hemispheric priming, brain activation, dual-task paradigms.Résumé Le concept d'amorçage désigne les processus par lesquels un hémisphère est éveillé avant l'exécution d'une tâche. Cet amorçage peut être effectué par l'engagement du sujet dans une autre tâche. Nous avons développé une situation de comparaison de stimuli présentés en champ visuel divisé. Les sujets doivent dire si deux stimuli sont identiques, avant, pendant ou après l'exécution d'une tâche activatrice. Cette épreuve consiste à frapper en boucle un rythme complexe. Les résultats montrent une augmentation du nombre de réponses correctes dans l'hémisphère activé avec un optimum lorsque la tâche principale est exécutée conjointement ou avec un délai de 1,5 seconde après la tâche d'amorçage. Les performances diminuent conjointement dans l'autre hémisphère. Le processus d'amorçage semble être une fonction temporelle caractérisée par une augmentation immédiate puis une diminution progressive des ressources de l'hémisphère impliqué. Utiliser les paradigmes double-tâche, notamment pour modifier la balance interhémisphérique d'activation, nécessite donc le contrôle des aspects dynamiques et de la diffusion de l'activation produite par la tâche d'amorçage. Mots-clés : amorçage hémisphérique, activation cérébrale, paradigme double-tâche.Sockeel P. Evolution temporelle d'un amorçage hémisphérique dans une situation double-tâche. In: L'année psychologique. 1995 vol. 95, n°1. pp. 47-62

Do individuals with intellectual disability select appropriate objects as landmarks when learning a new route?

Background The present study was aimed at investigating the selection of landmarks by individuals with intellectual disability (ID). The hypothesis was that they would be less efficient than individuals without IDs in the selection of landmarks when learning a new route. Methods The experiment took place in a natural setting with a group of participants with ID and a group of control participants matched by chronological age. The participants were first guided along a route situated in an unfamiliar district. Then, they had to guide the experimenter along the route while pointing to all the objects and features they found useful for wayfinding. Results The designated objects were categorised as a function of their landmarks properties. There were significant differences between the two groups for non‐permanent landmarks, distant landmarks and non‐unique landmarks. The two groups selected landmarks near intersections in the same proportions. However, the individuals with ID selected more non‐unique landmarks and less textual signage than the control group at these decision points. Conclusion Individuals with ID seem to be less efficient than individuals without disability in landmark selection. This may limit their wayfinding abilities in their day‐to‐day travelling. This may also account for their difficulties in obtaining the kind of spatial knowledge which relates to the configural structure of their environment