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Successful joint actions require precise temporal and spatial coordination between individuals who aim to achieve a common goal. A growing number of behavioral data suggest that to efficiently couple and coordinate a joint task, the actors have to represent both own and the partner's actions. However it is unclear how the motor system is specifically recruited for joint actions. To find out how the goal and the presence of the partner's hand can impact the motor activity during joint action, we assessed the functional state of 16 participants' motor cortex during observation and associated motor imagery of joint actions, individual actions, and non-goal-directed actions performed with either 1 or 2 hands. As an indicator of the functional state of the motor cortex, we used the reactivity of the rolandic magnetoencephalographic (MEG) beta rhythm following median-nerve stimulation. Motor imagery combined with action observation was associated with activation of the observer's motor cortex, mainly in the hemisphere contralateral to the viewed (and at the same time imagined) hand actions. The motor-cortex involvement was enhanced when the goal of the actions was visible but also, in the ipsilateral hemisphere, when the partner's hand was visible in the display. During joint action, the partner's action, in addition to the participant's own action, thus seems to be represented in the motor cortex so that it can be triggered by the mere presence of an acting hand in the peripersonal space., info:eu-repo/semantics/published

Comment, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Preference for previously seen, unfamiliar objects reflects a memory bias on affective judgment, known as the "mere exposure effect" (MEE). Here, we investigated the effect of time, post-exposure sleep, and the brain hemisphere solicited on preference generalization toward objects viewed in different perspectives. When presented in the right visual field (RVF), which promotes preferential processing in the left hemisphere, same and mirrored exemplars were preferred immediately after exposure. MEE generalized to much dissimilar views after three nights of sleep. Conversely, object presentation in the left visual field (LVF), promoting right hemisphere processing, elicited a MEE for same views immediately after exposure, then for mirror views after sleep. Most importantly, sleep deprivation during the first post-exposure night, although followed by two recovery nights, extinguished MEE for all views in the LVF but not in the RVF. Besides demonstrating that post-exposure time and sleep facilitate the generalization process by which we integrate various representations of an object, our results suggest that mostly in the right hemisphere, sleep may be mandatory to consolidate the memory bias underlying affective preference. These interhemispheric differences tentatively call for a reappraisal of the role of cerebral asymmetries in wake- and sleep-dependent processes of memory consolidation., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Recognizing people involves creating and retrieving links between distinct representations such as faces and names. In previous research we have shown that the retrieval of face/name associations produced cerebral activities lateralized in the left hemisphere and spreading from posterior to anterior sites after about 300ms. The present ERP study was performed to compare the specific electrophysiological activities elicited by the retrieval of face/proper name (FP) and animal/common name (AC) associations. Using a subtraction method to isolate the specific binding activities, we showed that both kinds of association produced two main posterior negative/anterior positive complexes, with a more frontal distribution for AC, and bilateral temporal activities. These findings confirm that general associative processes - independent of the kind of association - are not simply the sum of the activities elicited by each stimulus, and that they could involve both unimodal sensory and multimodal convergence regions of the brain., Journal Article, info:eu-repo/semantics/published

Metachromatic leukodystrophy (MLD) rarely has its clinical onset in young adults, with a combination of cognitive and behavioural symptoms and peripheral neuropathy. Here we present an exceptional case with very late onset at 42 years of age and no clinical or neurophysiological sign of peripheral neuropathy. Molecular analysis revealed compound heterozygosity for two novel missense mutations affecting conserved residues in the arylsulphatase A (ASA) sulphatase and carboxyterminal domains, resulting in an 89% loss of enzymatic activity. This case indicates that MLD needs to be considered in the differential diagnosis of very late onset white matter diseases, even if not accompanied by peripheral nerve involvement., Case Reports, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

To report long-term imaging follow-up and clinical outcome of 13 patients with a giant vertebrobasilar aneurysm treated by parent artery occlusion (PAO)., Case Reports, Journal Article, info:eu-repo/semantics/published

Several ERP studies have shown an orienting complex, the N2/P3a, associated to the detection of stimulus novelty. Its role consists in preparing the organism to process and react to biologically prepotent stimuli. Whether this N2/P3a: (1) could be obtained with complex visual stimuli, such as with emotional facial expressions; and (2) could take part in a complex discrimination process has yet to be determined. To investigate this issue, event-related potentials were recorded in response to repetitions of a particular facial expression (e.g. sadness) and in response to two different deviant (rare) stimuli, one depicting the same emotion as the frequent stimulus, while the other depicted a different facial expression (e.g. fear). As expected, deviant stimuli evoked an N2/P3a complex of larger amplitude than frequent stimuli. But more interestingly, when the deviant stimulus depicted the same emotion as the frequent stimulus the N2/P3a was delayed compared to the response elicited by the different-emotion deviant. The N2/P3a was thus implicated in the detection of physical facial changes, with a higher sensitivity to changes related to a new different emotional content, perhaps leading to faster adaptive reactions., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

We report a girl with refractory partial seizures since 7 years of age, secondary to right frontal cortical dysplasia, who developed MRI and SPECT abnormalities in the contralateral hemicerebellar cortex. These became more marked, leading to left hemicerebellar atrophy. Crossed cerebellar diaschisis has been described mostly in hemispheric stroke and supratentorial tumours, but less often in epilepsy. It is usually a transient phenomenon. This report shows that crossed cerebellar diaschisis can develop within two years of seizure onset and evolve over time., Case Reports, Journal Article, info:eu-repo/semantics/published

A PET study of seven normal individuals was carried out to investigate the neural populations involved in the retrieval of the visual representation of a face when presented with an associated name, and conversely. Face-name associations were studied by means of four experimental matching conditions, including the retrieval of previously learned (1) name-name (NN), (2) face-face (FF), (3) name-face (NF), and (4) face-name (FN) associations, as well as a resting scan with eyes closed. Before PET images acquisition, subjects were presented with 24 unknown face-name associations to encode in 12 male/female couples. During PET scanning, their task was to decide whether the presented pair was a previously learned association. The right fusiform gyrus was strongly activated in FF condition as compared to NN and Rest conditions. However, no specific activations were found for NN condition relative to FF condition. A network of three areas distributed in the left hemisphere, both active in (NF-FF) and (FN-NN) comparisons, was interpreted as the locus of the integration of visual faces and names representations. These three regions were localized in the inferior frontal gyrus (BA 45), the medial frontal gyrus (BA 6) and the supramarginal gyrus of the inferior parietal lobe (BA 40). An interactive model accounting for these results, with BA 40 seen as an amodal binding region, is proposed., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

We describe the case of a 58-years-old right-handed women suffering from an occipital-parietal lesion. The administration of a cognitively based assessment tool for limb praxis (Batterie d'Evaluation des Praxies, B.E.P. Peigneux and Van der Linden, 1998) demonstrated bilateral visuo-imitative apraxia. Gesture production was mainly characterised by spatial, errors, and imitation of meaningful gestures was worse than their pantomime on verbal command. Moreover, the imitation of meaningless gestures and their reproduction on a manikin were worse than imitation of their matched meaningful gestures. In a cognitive perspective, adapted from the Rothi et al. (1997) and Goldenberg (1995) contributions to our understanding of limb praxis, this configuration of performance suggests deficits occurring at multiple levels. On one hand, it suggests either access difficulties or alteration of the output praxicon, i.e. the lexicon for visuo-kinesthetic engrams of meaningful gestures. On the other hand, the simultaneous deficit for meaningless gesture reproduction on the subject's own body and on a manikin favors an alteration of the structural descriptions of the human body (i.e. human body knowledge), underlying the mental transposition processes occurring between the visual analysis of a meaningless gestural configuration and its effective reproduction on oneself or on a manikin, thus contradicting the classic view of a direct pathway linking visual analysis and motor planning in meaningless gesture imitation. Finally, due to the output praxicon deficit, imitation of meaningful gestures is partly processed in the same way as meaningless gestures (also impaired in this case), leading to an interference effect between both degraded memory-based and visually-transposed traces, which account for imitation of meaningful gestures being worse than their pantomime on verbal command. We also assess regional cerebral metabolism using positron emission tomography (PET). Comparison with 41 h, Case Reports, English Abstract, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Behavioral studies have shown that two different morphed faces belonging to the same identity are harder to discriminate than two faces stemming from two different identities. The temporal course of this categorical perception effect has been explored through event-related potentials. Three kinds of pairs were presented in a matching task: (1) two different morphed faces representing the same identity (within), (2) two other faces representing two different identities (between), and (3) two identical morphed faces (same). Following the second face onset in the pair, the amplitude of the right occipitotemporal negativity (N170) was reduced for within and same pairs as compared with between pairs, suggesting an identity priming effect. We also observed a modulation of the P3b wave, as the amplitude of the responses for within pairs was higher than for between and same pairs, suggesting a higher complexity of the task for within pairs. These results indicate that categorical perception of human faces has a perceptual origin in the right occipitotemporal hemisphere., Journal Article, Research Support, Non-U.S. Gov't, FLWIN, info:eu-repo/semantics/published

The inability to identify objects by manipulation with eyes closed (astereognosia) results from a focal cortical lesion of the second order parietal area 2, which integrates inputs from finger joints with tactile information., Letter, SCOPUS: ar.j, info:eu-repo/semantics/published

In unselected adult patients with brain damage, the Judgment of Line Orientation Test and the Facial Recognition Test are considered valid instruments for detecting right cerebral hemisphere lesions. It is unknown, however, whether this applies to children as well. Performance levels on the Judgment of Line Orientation Test and the Facial Recognition Test of 18 children with acquired left cerebral lesions and 14 children with acquired right cerebral lesions were reviewed. Subjects were unselected for age, sex, or etiology. Age-related norms were obtained in 81 normal controls, aged 7 to 14 years. Judgment of Line Orientation Test and Facial Recognition Test performance levels did not predict the presence of cerebral pathology per se in our unselected groups with demonstrated unilateral cerebral lesions, nor did they contribute to the prediction of the side of the lesion within the two groups with cerebral lesions. These results cast serious doubt on an important aspect of the clinical utility of both tests in children, namely their discriminative validity in the assessment of etiologically unselected populations with brain damage., Clinical Trial, Comparative Study, Controlled Clinical Trial, Journal Article, info:eu-repo/semantics/published

We investigated, by positron emission tomography (PET) with [18F]fluoro-2-deoxy-d-glucose (FDG) (FDG-PET), brain glucose metabolism in 19 patients with parkinsonian features. We compared local pattern of FDG uptake and asymmetry indexes in patients with therapeutic response to levodopa (L-dopa) (group 1, presumed Parkinson's disease, n = 9) and patients without L-dopa therapeutic response (group 2, presumed striatonigral degeneration, n = 10). Limb dystonia was present in 11% of patients in group 1 and in 40% of patients in group 2. Asymmetry in basal ganglia metabolism was distributed differently in the two groups (analysis of variance, p < 0.04). In superior and inferior putamen, superior and middle caudate, ventral striatum, and inferior thalamus, relative reduction in metabolism on the side contralateral to predominant parkinsonian signs was associated with L-dopa unresponsiveness. On the contrary, in middle caudate, ventral striatum, and inferior thalamus, a relative increase in metabolism on the side contralateral to the predominant side, parkinsonian signs were found in L-dopa-responsive patients. Our FDG-PET study using simple statistical procedures demonstrates inverse asymmetry of basal ganglia glucose metabolism in parkinsonian patients grouped on the sole basis of L-dopa responsiveness., Journal Article, Research Support, Non-U.S. Gov't, FLWIN, info:eu-repo/semantics/published

Cerebral glucose metabolism was studied in 20 underweight anorectic girls and in 10 age- and sex-matched healthy volunteers using positron emission tomography with (18-F)-fluorodeoxy-glucose. Both groups were scanned during rest, with eye closed and with low ambient noise. Compared to controls, the underweight anorectic group showed a global hypometabolism (p = .002) and an absolute (p < .001) as well as relative (p < .01) hypometabolism of glucose in cortical regions, with the most significant differences found in the frontal and the parietal cortices. Within the underweight anorectic and the control groups, no correlations were found between absolute or relative rCMRGlu and BMI, anxiety scores, or Hamilton scores of depression. Different factors might explain this reduction of glucose metabolism in anorexia nervosa. It might be the consequence of neurophysiological or morphological aspects of anorexia nervosa and/or the result of some associated symptoms such as anxiety or depressed feelings. Supported by cognitive studies, we can also hypothesize a primary corticocerebral dysfunctioning in anorexia nervosa., Journal Article, info:eu-repo/semantics/published

Positron emission tomography with [18F]-fluoro-2-deoxy-D-glucose as tracer was used to investigate frontal glucose metabolism in 15 unmedicated schizophrenic patients and 15 healthy subjects under resting conditions. Although no difference in absolute frontal cerebral metabolic rates of glucose (CMRglu) were found between schizophrenic patients and control subjects, relative measures significantly differentiated the two groups. Whole frontal metabolism and frontocaudate ratio were significantly decreased in both hemispheres in the patients. The results confirm the existence of hypofrontality in unmedicated schizophrenia and indicate disturbances in metabolic relationships between the frontal cortex and the striatum in this disorder., Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

The authors investigated brain glucose utilization using positron emission tomography (PET) in 12 normal volunteers and 12 unipolar unmedicated depressed patients (six endogenous; six nonendogenous) following injection of [18F]fluoro-deoxyglucose (FDG). Compared by analyses of variance, absolute and relative regional glucose metabolic rates appeared different in depressed patients and control subjects, especially in parietal and frontal lobes. In patients with unipolar depression, metabolic rates were increased in the orbital part of the frontal lobe and decreased in a frontal dorsolateral area. The metabolic supero-basal gradient calculated in the frontal cortex was significantly lower in depressed patients than in normal subjects. Decreased glucose metabolism was also observed in the parietal cortex of depressed patients. No differences in glucose metabolic rates have been detected between endogenous and nonendogenous patients. No correlation has been found between the metabolic data and the Hamilton Rating Scale., Journal Article, info:eu-repo/semantics/published

Case Reports, Journal Article, Research Support, Non-U.S. Gov't, info:eu-repo/semantics/published

Prerolandic and parietal SEPs to electrical stimulation of fingers or median nerve were studied with non-cephalic reference in 40 normal young adults and in 35 healthy octogenarians. Limb temperatures were 36-37 degrees C. Intersubject variations of SEP components were analysed. A new widespread component N18 was identified and shown to be generated below the cortex. This N18 is about the only early component recorded at the parietal ipsilateral region after the positive far-field potentials P9, P11 and P13-P14. Transit times along the central somatosensory pathway were replicated and discussed as well as other evidence about the sequential activation of the various neural structures involved. The N20 potential representing the earliest cortical response is recorded from the contralateral parietal region, but is absent ipsilaterally. The prerolandic potential is related to distinct generators and is elicited by a separate thalamocortical pathway rather than by corticocortical connections from areas 2 and 5 in parietal cortex. The changes associated with normal aging have been confirmed and extended., In Vitro, Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: ar.j, info:eu-repo/semantics/published

Journal Article, Research Support, Non-U.S. Gov't, SCOPUS: NotDefined.j, FLWNA, info:eu-repo/semantics/published, Evoked Potentials