Thierry Meulemans

Acquisition of new concepts by two amnesic patients

Two Korsakoff amnesics (A.G. and G.S.) and two control subjects were taught six new concepts. Each concept was composed of three parts: the name of the concept, the context in which the concept originated and its definition. The learning procedure consisted of two phases: (1) learning the concept names and definitions by means of the vanishing-cues method; (2) practice on examples of the concepts through a classification task: examples were either set in the same context as that given in the original definition or in mixed contexts (same and new contexts). Subjects were then tested after 24 hours, a week and a month on their ability to identify new examples as belonging to one of the conceptual rules studied (transfer tests). Both patients showed substantial learning. Patient A.G. was slow and dependent of the first letter cues in the vanishing-cues learning phase but nevertheless, she acquired a large and flexible conceptual knowledge and this was especially true for concepts that were practised by means of mixed-context examples. Patient G.S. easily learned to associate the definitions with the concept names but her conceptual knowledge remained more limited. These results confirm the existence of a semantic learning ability in amnesic patients. They also suggest that under appropriate learning conditions, amnesics may eventually acquire a new flexible conceptual knowledge.

Intact procedural motor sequence learning in developmental coordination disorder.

The purpose of the present study was to explore the possibility of a procedural learning deficit among children with developmental coordination disorder (DCD). We tested 34 children aged 6-12 years with and without DCD using the serial reaction time task, in which the standard keyboard was replaced by a touch screen in order to minimize the impact of perceptuomotor coordination difficulties that characterize this disorder. The results showed that children with DCD succeed as well as control children at the procedural sequence learning task. These findings challenge the hypothesis that a procedural learning impairment underlies the difficulties of DCD children in acquiring and automatizing daily activities. We suggest that the previously reported impairment of children with DCD on the serial reaction time task is not due to a sequence learning deficit per se, but rather due to methodological factors such as the response mode used in these studies.

Preserved artificial grammar learning in Parkinson's disease

The core behavioral features of confusional states are alterations in level of arousal, disturbances of attention and impairment in the logical stream of thought (Geschwind, 1982 in Lee & Hamsher, 1988). Confusional states have been known by different names and the DMS-IV uses the term delirium which is characterized by a disturbance of consciousness, reduced clarity of awareness of the environment, easily distracted by irrelevant stimuli, and an accompanying change in cognition. The latter may include memory impairment, disorientation, language disturbance and perceptual disturbances. Behaviorally, these patients have been observed to show language and communicative impairments including metaphorical language use. The question thus arises at what level these patients show adequate semantic processing and at which point it breaks down. One means to investigate this question is to use the ERP technique, and in particular the occurrence of the N400.

Beyond the experience: Detection of metamemorial regularities

We examined the mechanisms involved in the development of the easily learned, easily remembered (ELER) heuristic in three groups of young children (4-5 years, 6-7 years, and 8-9 years). A trial-to-acquisition procedure was used to evaluate how much these childrens judgment of learning depended on the ELER heuristic. Moreover, a new experimental paradigm, composed of six phases-a pretest, four training phases, and a posttest-was employed to implicitly influence the validity of the ELER association that underlies this metacognitive rule. Results revealed that the ELER heuristic develops early (4-5years), but its use is reduced after implicit training. Furthermore, executive monitoring was found to account for the smaller changes observed in older children (8-9 years) after training. From a developmental perspective, these findings present a coherent picture of childrens learning of metacognitive heuristics, wherein early automatic and implicit learning is later followed by effortful control.

Visual neglect: Is there a relationship between impaired spatial working memory and re-cancellation?

AbstractIn visual search tasks, neglect patients tend to explore and repeatedly re-cancel stimuli on the ipsilesional side, as if they did not realize that they had previously examined the rightward locations favoured by their lateral bias. The aim of this study was to explore the hypothesis that a spatial working memory deficit explains these ipsilesional re-cancellation errors in neglect patients. For the first time, we evaluated spatial working memory and re-cancellation through separate and independent tasks in a group of patients with right hemisphere damage and a diagnosis of left neglect. Results showed impaired spatial working memory in neglect patients. Compared to the control group, neglect patients cancelled fewer targets and made more re-cancellations both on the left side and on the right side. The spatial working memory deficit appears to be related to re-cancellations, but only for some neglect patients. Alternative interpretations of re-exploration of space are discussed.

Later learning stages in procedural memory are impaired in children with Specific Language Impairment

BACKGROUND According to the Procedural Deficit Hypothesis (PDH), difficulties in the procedural memory system may contribute to the language difficulties encountered by children with Specific Language Impairment (SLI). Most studies investigating the PDH have used the sequence learning paradigm; however these studies have principally focused on initial sequence learning in a single practice session. AIMS The present study sought to extend these investigations by assessing the consolidation stage and longer-term retention of implicit sequence-specific knowledge in 42 children with or without SLI. METHODS AND PROCEDURES Both groups of children completed a serial reaction time task and were tested 24h and one week after practice. OUTCOMES AND RESULTS Results showed that children with SLI succeeded as well as children with typical development (TD) in the early acquisition stage of the sequence learning task. However, as training blocks progressed, only TD children improved their sequence knowledge while children with SLI did not appear to evolve any more. Moreover, children with SLI showed a lack of the consolidation gains in sequence knowledge displayed by the TD children. CONCLUSIONS AND IMPLICATIONS Overall, these results were in line with the predictions of the PDH and suggest that later learning stages in procedural memory are impaired in SLI.

Support for distinct subcomponents of spatial working memory: A double dissociation between spatial-simultaneous and spatial-sequential performance in unilateral neglect

Over the last decade, many studies have demonstrated that visuospatial working memory (VSWM) can be divided into separate subsystems dedicated to the retention of visual patterns and their serial order. Impaired VSWM has been suggested to exacerbate left visual neglect in right-brain-damaged individuals. The aim of this study was to investigate the segregation between spatial–sequential and spatial–simultaneous working memory in individuals with neglect. We demonstrated that patterns of results on these VSWM tasks can be dissociated. Spatial–simultaneous and sequential aspects of VSWM can be selectively impaired in unilateral neglect. Our results support the hypothesis of multiple VSWM subsystems, which should be taken into account to better understand neglect-related deficits.

Age-related differences in perceptuomotor procedural learning in children

Procedural learning is generally considered to proceed in a series of phases, with cognitive resources playing an important role during the initial step. From a developmental perspective, little is known about the development of procedural learning or the role played by explicit cognitive processes during learning. The main objectives of this study were (a) to determine whether procedural learning performance improves with age by comparing groups of 7-year-old children, 10-year-old children, and adults and (b) to investigate the role played by executive functions during the acquisition in these three age groups. The 76 participants were assessed on a computerized adaptation of the mirror tracing paradigm. Results revealed that the youngest children had more difficulty in adapting to the task (they were slower and committed more errors at the beginning of the learning process) than 10-year-olds, but despite this age effect observed at the outset, all children improved performance across trials and transferred their skill to a different figure as well as adults. Correlational analyses showed that inhibition abilities play a key role in the performance of 10-year-olds and adults at the beginning of the learning but not in that of 7-year-olds. Overall, our results suggest that the age-related differences observed in our procedural learning task are at least partly due to the differential involvement of inhibition abilities, which may facilitate learning (so long as they are sufficiently developed) during the initial steps of the learning process; however, they would not be a necessary condition for skill learning to occur.

The childhood executive function inventory: confirmatory factor analyses and cross-cultural clinical validity in a sample of 8- to 11-year-old children.

Objective: The aim was to investigate the psychometric characteristics of the French adaptation of the Childhood Executive Functioning Inventory (CHEXI) in children and to explore the cross-cultural validity of the CHEXI in discriminating between children with ADHD and controls in two culturally different samples (Belgian and Swedish). Method: Study I included normally developing children (n = 242), whereas Study II included both children diagnosed with ADHD (n = 87) and controls (n = 87). CHEXI ratings were collected from parents. Results: Confirmatory factor analyses replicated the two-factor solution, referred to as inhibition and working memory, which had been identified previously. Both subscales had good psychometric properties. Furthermore, the CHEXI was found to discriminate, with high sensitivity and specificity, between children with ADHD and controls in both cultural samples. Conclusion: The CHEXI can be considered as a valuable screening measure for ADHD in children, but the cross-cultural clinical implications of ratings have to be considered.

Procedural learning, consolidation, and transfer of a new skill in Developmental Coordination Disorder.

The aim of this study was to explore the differences in procedural learning abilities between children with DCD and typically developing children by investigating the steps that lead to skill automatization (i.e., the stages of fast learning, consolidation, and slow learning). Transfer of the skill to a new situation was also assessed. We tested 34 children aged 6–12 years with and without DCD on a perceptuomotor adaptation task, a form of procedural learning that is thought to involve the cerebellum and the basal ganglia (regions whose impairment has been associated with DCD) but also other brain areas including frontal regions. The results showed similar rates of learning, consolidation, and transfer in DCD and control children. However, the DCD childrens performance remained slower than that of controls throughout the procedural task and they reached a lower asymptotic performance level; the difficulties observed at the outset did not diminish with practice.