Philippe Allain

Cognitive inhibition and working memory in unipolar depression.

BACKGROUND Over the past decade, evidence has accumulated to suggest that people suffering from Major Depressive Disorder (MDD) present impairment in attention, working memory, executive function, including cognitive inhibition, problem- and task-planning. The aim of the current study was to assess inhibitory mechanisms within working memory with emotionally neutral material in a group of patients suffering from MDD. We hypothesized that impairment in cognitive inhibition is global and not only due to the emotional valence of the stimuli employed for the tasks. METHODS Twenty patients with MDD (DSM-IV) and 20 healthy controls were recruited. To assess cognitive inhibition, we used neutral material, in the form of the Prose Distraction Task (PDT) (Connelly SL, 1991), Trail Making Test (TMT), Modified Card Sorting Test (MCST), Rule Shift Cards (RSC), Stroop test and Hayling Sentence Completion test (HSC). The Modified 6 elements test, the Brixton Spatial Anticipation test, the dual task performance and the verbal fluencies test were also used to assess other executive function such as flexibility, planning tasks and memory. RESULTS Individuals with depression showed impairment in cognitive inhibition. They made more errors on the PDT, alongside slower response times. Slower response times were also observed on the Stroop, TMT and RSC. The MDD group made more errors in HSC and performed worse than controls in the semantic part of verbal fluency and Modified 6 elements tasks. The impairment of access function was significantly associated with the level of depression. CONCLUSION Depressed patients showed inability to inhibit neutral information access to working memory, restrain and delete irrelevant information. This impairment in cognitive inhibition could underlie cognitive slowness and attentional deficits in depression.

What about theory of mind after severe brain injury

Background: Behavioural changes are often reported after a severe traumatic brain injury (TBI). These changes are usually a greater burden for relatives than physical or cognitive impairments. This study investigated social cognition in TBI patients using two theory of mind (TOM) tasks. Method: The performances of 17 patients with severe TBI and 17 matched controls were compared on two tasks designed to investigate understanding of other peoples mental states: The ‘Reading the Mind in the Eyes’ test (RME) and the ‘Character Intention Task’ (CIT). TBI patients and controls were also given several executive function tasks. Results: Compared to healthy controls, patients were impaired in most executive tests and in both TOM tasks. No relationship was found between TOM and executive measures. This is consistent with Rowes position, who suggested an independence between executive functioning and social cognition. These data suggest that TBI patients may have specific social intelligence disturbances. Conclusion: Future work should employ additional tests of TOM and behavioural ratings and recruit more patients in order to complete analysis.

Unusual use of objects after unilateral brain damage. The technical reasoning model

It has been suggested that gesture engrams, conceptual knowledge and/or the ability to infer function from structure can support object use. The present paper proposes an alternative view which is based upon the idea that object use requires solely the ability to reason about technical means provided by objects. Technical means are abstract principles which are not linked with any object representation (e.g., cutting involves the opposition between dense and permeable material). The technical reasoning model predicts that the inability to perform technical reasoning should impair performance in any situation requiring the use of objects (in a conventional way or not). Twenty left brain-damaged (LBD) patients, 11 right brain-damaged (RBD) patients and 41 healthy controls were examined on experimental tests assessing the conventional use of objects (e.g., screwing a screw with a screwdriver), conceptual knowledge about object function, pantomime of object use and recognition of object utilization gestures. We also designed the Unusual Use of Objects Test, which demands unusual applications of objects to achieve a purpose for which the usually applied object is not provided (e.g., screwing a screw with a knife). The key findings are that only LBD patients have more difficulties on the Unusual Use of Objects Test than controls or RBD patients, and that the severity of their impairment is correlated with that on conventional use of objects. Correlations with tests assessing conceptual knowledge as well as with tests of pantomime of object use and recognition of object utilization gestures were weaker. These results support the technical reasoning model and question the role of conceptual knowledge and gesture engrams in object use. Since the technical reasoning model also predicts two distinct technical disorders, the discussion focuses on the existence of these disorders in regard to individual performance profiles obtained in the Unusual Use of Objects Test.

Cognitive changes in asymptomatic carriers of the Huntington disease mutation gene

Huntington disease (HD) is a neurodegenerative disorder due to an excessive number of CAG repeats in the IT15 gene on chromosome 4. Studies of cognitive function in asymptomatic gene carriers have yielded contradictory results. This study compared cognitive performance in 44 subjects with the HD mutation (group of carriers) who had no clinical signs of HD and 39 at‐risk individuals without HD mutation (group of non‐carriers). Neuropsychological evaluation focused on global cognitive efficiency, psychomotor speed, attentional, executive and memory functions. Significant differences, with lower performances in the group of gene carriers, were detected for some measures of psychomotor speed, attention and executive functioning (all P < 0.01). More differences between groups were observed for memory measures, in particular on the California Verbal Memory Test. Complementing these observations, cognitive scores were correlated with age in the group of gene carriers, but not in the group of non‐carriers. This suggests that the cognitive changes precede the appearance of the motor and psychiatric symptoms in HD and that tests proved to be sensitive to early HD deficiencies are better suited than global cognitive efficiency scales to observe them.

Executive dysfunction in children with neurofibromatosis type 1: a study of action planning.

In this study, we tested the hypothesis that action planning is impaired in children with neurofibromatosis type 1 (NF1). Thirty-six children with NF1 were pair-matched to 36 healthy controls (HC) on age (range, 7-12 years), sex, and parental education level, and both groups were administered three action-planning tasks. To examine the relation of task performance to attention deficit hyperactivity disorder (ADHD), the NF1 group was divided into subsets of children who met or did not meet criteria for ADHD. Children with NF1 performed less well than HC on all planning tasks, and differences remained when controlling for IQ or a measure of visuospatial skill. Both the NF1 with ADHD subset and NF1 without ADHD subset performed more poorly than HC on two of the tasks, whereas only the NF1 with ADHD subset performed worse than HC on the third planning task. The results underscore the importance of evaluating executive function in children with NF1 and suggest that deficits in this domain may be only partially related to ADHD. Planning deficits in children with NF1 may be part of their cognitive phenotype. Identifying these deficits is relevant in determining factors contributing to learning problems and in developing appropriate interventions.

Directed forgetting of autobiographical memory in mild Alzheimer's disease

Using the autobiographical directed forgetting method (Barnier et al., 2007), the present paper addressed the intentional inhibitory processes of episodic and semantic autobiographical memory in Alzheimers disease (AD). Mild AD patients and healthy elderly people were instructed to either forget or to continue remembering previously generated autobiographical events. In a later recall test they were asked to reconstruct the early-generated memories regardless of the forget/remember instruction. Autobiographical reconstruction was further distributed into episodic and semantic memories. Results showed no forget instruction effect on episodic or semantic autobiographical recall with AD patients, whereas healthy elderly people were able to inhibit only episodic autobiographical memories. The findings suggest an impairment of the intentional inhibitory processes in autobiographical memory with AD and a relative preservation of these mechanisms with normal ageing. They also demonstrate an earlier decline in the intentional inhibitory processes compared to the autobiographical deterioration in AD.

Object utilization and object usage: A single-case study

ABSTRACT It has been suggested that both conceptual knowledge and the ability to infer function from structure can support object use. By contrast, we propose that object use requires solely the ability to reason about technical ends. Technical ends (e.g., cutting) are not purposes (e.g., eating), but the technical way to achieve them. This perspective suggests that there is no mutual relationship between technical ends and purposes since the same purpose (e.g., writing) can be achieved thanks to distinct technical ends (graving, tracing), and, inversely, the same technical end (e.g., tracing) can achieve different purposes (making up, writing). Thus, conceptual knowledge might determine which technical end is usually associated with a given purpose. To contribute to the discussion, we described the behaviour of a female patient with left temporal lobe lesions and bilateral frontal lobe lesions following a closed-head injury. Conceptual knowledge was impaired. She encountered difficulties in demonstrating the use of objects in isolation (e.g., using a screwdriver without the screw). The presence of a recipient (e.g., using a screwdriver with the screw) improved her performance. The performance was also normal when asked to perform unusual applications of objects to achieve a goal for which the usually applied object was not provided (e.g., screwing a screw with a knife). Consistent with the theoretical framework supported here, her performance profile suggests an intact ability to reason about technical ends (i.e., utilization), in the presence of a defective ability to determine the usual relationship between technical ends and purposes (i.e., usage).

To what extent does destination recall induce episodic reliving? Evidence from Alzheimer's disease.

We compared destination memory to source memory in patients with Alzheimer’s disease (AD), as the latter type of memory is believed to be severely deteriorated in AD. Control participants and AD patients were tested on two conditions, both of which had a study phase and a recognition phase. In the study phase of the first condition, participants had to tell a set of facts to the faces of a set of celebrities (destination memory). In the study phase of the second condition, they had to receive a different set of facts from a different set of celebrity faces (source memory). During the recognition phase, participants had to indicate, for destination memory, whether they had previously told a given fact to a given face (yes) or not (no) and, for source memory, whether they had previously received a given fact from a given face (yes) or not (no). In both conditions, they were asked to choose between “remember” or “know” options when answering “yes.” AD patients showed reliable difficulties in destination recall, accompanied by a significant decrease in the number of “remember” responses they gave. AD-related destination memory decline may be attributed to the perturbation of episodic memory and its autonoetic reliving. The potential neural bases of this decline are discussed in terms of hippocampal failures.

Prospective and retrospective time perception are related to mental time travel: evidence from Alzheimer's disease.

Unlike prospective time perception paradigms, in which participants are aware that they have to estimate forthcoming time, little is known about retrospective time perception in normal aging and Alzheimers disease (AD). Our paper addresses this shortcoming by comparing prospective and retrospective time estimation in younger adults, older adults, and AD patients. In four prospective tasks (lasting 30s, 60s, 90s, or 120s) participants were asked to read a series of numbers and to provide a verbal estimation of the reading time. In four other retrospective tasks, they were not informed about time judgment until they were asked to provide a verbal estimation of four elapsed time intervals (lasting 30s, 60s, 90s, or 120s). AD participants gave shorter verbal time estimations than older adults and younger participants did, suggesting that time is perceived to pass quickly in these patients. For all participants, the duration of the retrospective tasks was underestimated as compared to the prospective tasks and both estimations were shorter than the real time interval. Prospective time estimation was further correlated with mental time travel, as measured with the Remember/Know paradigm. Mental time travel was even higher correlated with retrospective time estimation. Our findings shed light on the relationship between time perception and the ability to mentally project oneself into time, two skills contributing to human memory functioning. Finally, time perception deficits, as observed in AD patients, can be interpreted in terms of dramatic changes occurring in frontal lobes and hippocampus.

Different constraints on grip selection in brain-damaged patients: Object use versus object transport

The present study discusses the presence of different constraints on action selection during object use versus object transport. Sixteen left brain-damaged (LBD) patients, 10 right brain-damaged (RBD) and 35 healthy controls were examined on a grip preference test consisting of a grasping-to-transport and a grasping-to-use condition. Assessment included a general praxis testing (pantomime production, object utilization gesture recognition and object use). We also reported the case of a close-head injury patient (DR) with an atypical behavioural pattern. Our results supported the different constraint hypothesis. While several LBD and RBD patients performed inappropriate grips in the grasping-to-transport condition, only two patients (L2 and DR) used inappropriate grips in the grasping-to-use condition. No correlation was found between the two conditions of the grip preference test and measures of the general praxis testing. The discussion focuses on the nature of constraints on grip selection during object use and object transport.