Lying in neuropsychology.

The issue of lying occurs in neuropsychology especially when examinations are conducted in a forensic context. When a subject intentionally either presents non-existent deficits or exaggerates their severity to obtain financial or material compensation, this behaviour is termed malingering. Malingering is discussed in the general framework of lying in psychology, and the different procedures used by neuropsychologists to evidence a lack of collaboration at examination are briefly presented and discussed. When a lack of collaboration is observed, specific emphasis is placed on the difficulty in unambiguously establishing that this results from the patient's voluntary decision.

Mild cognitive impairment: differential atrophy in the hippocampal subfields.

BACKGROUND AND PURPOSE: Hippocampus volumetry is a useful surrogate marker for the diagnosis of Alzheimer disease, but it seems insufficiently sensitive for the aMCI stage. We postulated that some hippocampus subfields are specifically atrophic in aMCI and that measuring hippocampus subfield volumes will improve sensitivity of MR imaging to detect aMCI. MATERIALS AND METHODS: We evaluated episodic memory and hippocampus subfield volume in 15 patients with aMCI and 15 matched controls. After segmentation of the whole hippocampus from clinical MR imaging, we applied a new computational method allowing fully automated segmentation of the hippocampus subfields. This method used a Bayesian modeling approach to infer segmentations from the imaging data. RESULTS: In comparison with controls, subiculum and CA2-3 were significantly atrophic in patients with aMCI, whereas total hippocampus volume and other subfields were not. Total hippocampus volume in controls was age-related, whereas episodic memory was the main explanatory variable for both the total hippocampus volume and the subfields that were atrophic in patients with aMCI. Segmenting subfields increases sensitivity to diagnose aMCI from 40% to 73%. CONCLUSIONS: Measuring CA2-3 and subiculum volumes allows a better detection of aMCI.

Cognitive deficits in patients with chronic fatigue syndrome compared to those with major depressive disorder and healthy controls.

OBJECT: Chronic fatigue syndrome (CFS) patients report usually cognitive complaints. They also have frequently comorbid depression that can be considered a possible explanation for their cognitive dysfunction. We evaluated the cognitive performance of patients with CFS in comparison with a control group of healthy volunteers and a group of patients with MDD. PATIENTS AND METHODS: Twenty-five patients with CFS, 25 patients with major depressive disorder (MDD), and 25 healthy control subjects were given standardized tests of attention, working memory, and verbal and visual episodic memory, and were also tested for effects related to lack of effort/simulation, suggestibility, and fatigue. RESULTS: Patients with CFS had slower phasic alertness, and also had impaired working, visual and verbal episodic memory compared to controls. They were, however, no more sensitive than the other groups to suggestibility or to fatigue induced during the cognitive session. Cognitive impairments in MDD patients were strongly associated with depression and subjective fatigue; in patients with CFS, there was a weaker correlation between cognition and depression (and no correlation with fatigue). CONCLUSIONS: This study confirms the presence of an objective impairment in attention and memory in patients with CFS but with good mobilization of effort and without exaggerated suggestibility.

[Cognitive rehabilitation]. / La rééducation cognitive.

During these last 30 years, cognitive rehabilitation has accomplished dramatic improvement. In this paper, we review progress in four main domains: the development of pragmatic and ecological approaches in neuropsychological rehabilitation; the development of computerised rehabilitation; rehabilitation of executive functions; cognitive rehabilitation in degenerative dementia. Finally, we present a single-case study, recently published elsewhere, showing the effectiveness of rehabilitation of verbal working memory in a patient with left hemisphere stroke. In addition, future issues for rehabilitation research are presented. The development of bottom-up rehabilitation strategies as well as the use of inter-hemispheric interactions appears as future promising tracks for clinical rehabilitation.

Rehabilitation of the central executive component of working memory: a re-organisation approach applied to a single case.

This paper describes and evaluates a programme of neuropsychological rehabilitation which aims to improve three sub-components of the working memory central executive: processing load, updating and dual-task monitoring, by the acquisition of three re-organisation strategies (double coding, serial processing and speed reduction). Our programme has two stages: cognitive rehabilitation (graduated exercises subdivided into three sub-programmes each corresponding to a sub-component) which enables the patient to acquire the three specific strategies; and an ecological rehabilitation, including analyses of scenarios and simulations of real-life situations, which aims to transfer the strategies learned to everyday life. The programme also includes information meetings. It was applied to a single case who had working memory deficits after a surgical operation for a cerebral tumour on his left internal temporal ganglioglioma. Multiple baseline tests were used to measure the effectiveness of the rehabilitation. The programme proved to be effective for all three working memory components; a generalisation of its effects to everyday life was observed, and the effects were undiminished three months later.

Hypothyroidism and major depression: a common executive dysfunction?

Little is known about the possible link between the cognitive disorders associated with hypothyroidism and those encountered in depression. This study examines attentional and executive functions as well as the intensity of anxiety and depressive symptoms in hypothyroidism and major depression and the possible link between these symptoms and cognitive disturbances. This study confirms the existence of psychomotor slowing associated with attentional and executive disturbance in major depression as well as in hypothyroidism. However, while depressed subjects manifested a conscious bias with material of negative emotional valence, no such bias was found in the hypothyroid subjects. While the hypothyroid state is accompanied by anxiety/depressive symptoms, it seems that the latter are too discrete for an attentional bias to be observed with material with a negative emotional valence.

Non-algorithmic access to calendar information in a calendar calculator with autism.

The possible use of a calendar algorithm was assessed in DBC, an autistic "savant" of normal measured intelligence. Testing of all the dates in a year revealed a random distribution of errors. Re-testing DBC on the same dates one year later shows that his errors were not stable across time. Finally, DBC was able to answer "reversed" questions that cannot be solved by a classical algorithm. These findings favor a non-algorithmic retrieval of calendar information. It is proposed that multidirectional, non-hierarchical retrieval of information, and solving problems in a non-algorithmic way, are involved in savant performances. The possible role of a functional rededication of low-level perceptual systems to the processing of symbolic information in savants is discussed.

Anxiety and depression, attention, and executive functions in hypothyroidism.

BACKGROUND: Divergences in cognitive disturbances in hypothyroidism reported in the literature are a result of a methodological bias. METHODS: By using a precise methodology, we examined attention and executive functions in hypothyroidism, verified the presence of anxiety and depressive symptoms in hypothyroidism, and examined the possible link between these symptoms and the cognitive disturbances (searching for attentional bias for words with a negative emotional valence). We administered a battery of cognitive tests to 23 participants who had undergone thyroidectomy for thyroid carcinoma: for the first time in an euthyroid state, then 3 weeks later (still in the euthyroid state) to assess the test/retest effect, and finally 4 weeks later in an hypothyroid state. We compared their performance with that of a group of 26 control participants who were also administered the same cognitive tests, also 3 times. RESULTS: In hypothyroidism, the thyroid participants were more anxious and depressed than the controls and presented attentional and executive disturbances that reflected general slowing and difficulties in using their capacities of inhibition. However, they did not exhibit an attentional bias for words with a negative emotional valence. CONCLUSIONS: Contrary to what was expected, symptoms of anxiety and not symptoms of depression interfered with the cognitive performance of participants in hypothyroidism.

Involvement of short-term memory in complex mental calculation.

The aim of this study was to examine the involvement of the short-term memory system in complex mental addition by manipulating the phonological and visual similarity of two numbers to be added. The phonological similarity of the problems appeared to have a major effect on both speed and accuracy. However, the manipulation of visual similarity failed to have any measurable impact. This suggests that the phonological loop, rather than the visual-spatial sketch pad, would be used preferably for temporary storage of addends. An interpretation of these results in terms of the nature of the internal code underlying this task is discussed.

Mental calculation in a prodigy is sustained by right prefrontal and medial temporal areas.

Calculating prodigies are individuals who are exceptional at quickly and accurately solving complex mental calculations. With positron emission tomography (PET), we investigated the neural bases of the cognitive abilities of an expert calculator and a group of non-experts, contrasting complex mental calculation to memory retrieval of arithmetic facts. We demonstrated that calculation expertise was not due to increased activity of processes that exist in non-experts; rather, the expert and the non-experts used different brain areas for calculation. We found that the expert could switch between short-term effort-requiring storage strategies and highly efficient episodic memory encoding and retrieval, a process that was sustained by right prefrontal and medial temporal areas.

Neuroanatomical substrates of arabic number processing, numerical comparison, and simple addition: a PET study.

Positron emission tomography was used to localize the cerebral networks specifically involved in three basic numerical processes: arabic numeral processing, numerical magnitude comparison, and retrieval of simple addition facts. Relative cerebral blood flow changes were measured while normal volunteers were resting with eyes closed, making physical judgment on nonnumerical characters or arabic digits, comparing, or adding the same digits. Processing arabic digits bilaterally produced a large nonspecific activation of occipito-parietal areas, as well as a specific activation of the right anterior insula. Comparison and simple addition fact retrieval revealed a fronto-parietal network involving mainly the left intraparietal sulcus, the superior parietal lobule and the precentral gyrus. Comparison also activated, but to a lesser extent, the right superior parietal lobe, whereas addition also activated the orbito-frontal areas and the anterior insula in the right hemisphere. Implications for current anatomo-functional models of numerical cognition are drawn.

Number processing and calculation in a case of visual agnosia.

We describe the performance of a brain-damaged subject who suffered from visual agnosia leading to major difficulties in generating and exploiting visual representations from long-term memory. His performance in a physical judgement task in which he was required to answer questions about the visual shapes of Arabic numerals reflected his agnosic problems. However, he showed no impairment in usual number processing and calculation tasks. This case shows that, despite some commonalities in number and object processing, actual numerical processes are not affected by visual agnosia and can be preserved even when fine visual processes are impaired.

Noncommutability of the N + 0 arithmetical rule: a case study of dissociated impairment.

It has been shown that some arithmetical problems are stored in the form of individual facts representations (e.g., 3 x 4 = 12) whereas others are solved by general stored rules (e.g., 0 x N = 0). We describe the performance of a brain-damaged subject who presented a mild impairment in arithmetical fact retrieval. Although her performance was almost perfect for rule-based problems in all arithmetical operations, she was severely impaired for 0 + n problems in contrast with her relatively good performance for the corresponding n + 0 problems. This dissociation extends to addition the noncommutability of arithmetical rules described in multiplication.

The odd-even effect in multiplication: parity rule or familiarity with even numbers?

This study questions the evidence that a parity rule is used during the verification of multiplication. Previous studies reported that products are rejected faster when they violate the expected parity, which was attributed to the use of a rule (Krueger, 1986; Lemaire & Fayol, 1995). This experiment tested an alternative explanation of this effect: the familiarity hypothesis. Fifty subjects participated in a verification task with contrasting types of problems (even x even, odd x odd, mixed). Some aspects of our results constitute evidence against the use of the parity rule: False even answers were rejected slowly, even when the two operands were odd. We suggest that the odd-even effect in verification of multiplication could not be due to the use of the parity rule, but rather to a familiarity with even numbers (three quarters of products are indeed even).

Physostigmine results in an increased decrement in brain glucose consumption in Alzheimer's disease.

The responsibility of cerebral cholinergic lesions for the weak clinical response to cholinergic neurotransmission enhancement of Alzheimer's disease (AD) was studied by measuring the effects of physostigmine on glucose consumption and neuropsychological tests. Ten AD and ten aged normals (AN) were examined twice, under placebo and under maximal tolerated dose of physostigmine, in randomized order and blind fashion. Under physostigmine, both groups showed better performances in tests measuring attention (P < 0.05-0.001) but not long-term memory, and cerebral glucose consumption was regionally modified (P < 0.0001). We observed a regional decrease in AD and in AN which was larger in AD, where each patient exhibited a mean metabolic decrease. With normalized values, AD and AN showed a similar decrease in the metabolic values of prefrontal cortex and striatum (P = 0.0003). These findings suggest that cholinergic neurotransmission enhancement depresses glucose consumption and increases selective attention in similar ways in both groups, but to a larger extent in AD. This suggests that brain metabolism in AD over-responds to enhancement of cholinergic neurotransmission. The observed weak response of clinical symptomatology to anticholinesterase agents does not appear to be due to the failure to enhance the activity of the cholinergic system in AD.

[A case of metamorphopsia restricted to faces and different familiar objects]. / Etude d'un cas de métamorphopsie limitée aux visages et à certains objets familiers.

The case of a 19-year old patient suffering of transient metamorphopsia restricted to familiar faces and familiar objects is reported. This clinical sign resulted from a small right occipitotemporal haemorrhage due to a sub-cortical metastasis. The patient claimed that faces are distorted and look more pleasant. There were neither visual field defects nor visual agnosia. MRI revealed a small high signal area in the right fusiform gyrus. The structural and functional aspects of the metamorphopsia are documented and discussed in relation to aperceptive prosopagnosia. More specifically, it is suggested that facial metamorphopsia and aperceptive prosopagnosia express the same underlying disorder differing only in terms of severity.

Lexicalization errors in writing arabic numerals: a single-case study.

This paper presents a single-case study of a patient suffering from several impairments in number processing. The main focus of the paper is to describe and interpret the patient's errors in verbal to arabic transcoding. The errors were of the syntactical type and consisted of partial lexicalizations appearing mainly in response to items with Thousand in sum relationships and less frequently with Hundred in sum relationships. The Discussion section compares three models in their ability to account for the patient's dissociation. It was suggested that models such as that of McCloskey, Caramazza, and Basili (1985), postulating a semantic representation for numbers built up on a base-ten system, are unable to account for the patient's errors. By contrast, Power et al.'s perspective (Power & Longuet-Higgins, 1978; Power & Dal Martello, 1990), which posits a semantic representation of numbers reflecting the structure of the verbal numeral system, could provide an economical interpretation for the dissociation observed between the mastery of sum and product relationships. Similarly, the asemantic transcoding model developed by Deloche and Seron (1987) gives a valid account for the patient's profile.

Selective impairment as evidence for mental organisation of arithmetical facts: BB, a case of preserved subtraction?

We report here the case of a patient (BB), suffering from a precocious evolving dementia with impaired arithmetic performance, who showed specific and theoretical pertinent dissociations in basic mental arithmetic. First, in a task involving production of answers to simple arithmetic problems, a strong dissociation was found among operation: while multiplication was severely impaired, addition was moderately and subtraction only slightly impaired. A second dissociation was found between problems potentially solvable by rules and the others, with the former being better preserved. Finally, in multiplication verification tasks, the rate and distribution of errors among problems were not different from those observed in the multiplication production task. This pattern of performance like the one presented by the patient RG (Dagenbach and McCloskey, 1992), suggests first that stored arithmetical fact representations are segregated by arithmetic operation and second that a distinction has to be drawn between arithmetical rules and arithmetical facts. Last, the parallelism of performance observed here in verification and production tasks suggests that the same deficit(s) is (are) responsible for errors in both tasks.

Calculation and number processing: assessment battery; role of demographic factors.

This paper describes the structure and contents of EC301, a standardized testing battery for the evaluation of brain-damaged adults in the area of calculation and number processing. The battery was administered to 180 normal subjects stratified by education (3 levels), age (3) and gender. EC301 is composed of a large variety of tasks dealing with basic arithmetic skills, and their linguistic, spatial, and mnesic dimensions. The three main notational systems for numbers--Arabic digits, written verbal, and spoken verbal number forms--are explored. Analysis of error rates indicated the effect of some demographic factors (principally, education; incidentally, gender) on normal performance in some tasks.

Patterns of line bisection in patients suffering from unilateral spatial neglect.

Thirteen patients suffering from Unilateral Spatial Neglect and 6 Right Brain Damaged Control Patients were tested on a line bisection task in order to verify peculiar patterns of error. Stimuli were arranged in order to avoid confounding the effects of line length and line position in the space. Two parameters of rightward displacement of setting point were used: 1) the distance of patient's setting point from actual line midpoint, and 2) the deduced left end-point of the line that patient took into account. Results showed that: 1) the rightward extension of lines did not lead to a consistent rightward displacement of setting point; 2) error significantly increased as lines extended more than 10 cm in the left hemispace; 3) the USN severity amplified the degradation of leftmost portion of stimuli until the deduced left endpoint of all space/length conditions was aligned on the left of patient's sagittal midplane. The interpretation of these results points to the particular arrangement of neurons directing attention on specific portions of the visual field.