Biomedical subjects

Jean-Luc Martinot

Publications and source records attributed to Jean-Luc Martinot.

8 recordsLinked to original sources

PubMed2006

Brain morphometry and cognitive performance in detoxified alcohol-dependents with preserved psychosocial functioning.

The extent of structural brain damage and related cognitive deficits has been little described in alcohol-dependent individuals with preserved social functioning. Thus, we investigated the relationship between regional alterations, executive performance, and drinking history. Volumes of gray and white matter were assessed using magnetic resonance imaging voxel-based morphometry in healthy men and in detoxified alcohol-dependent men with good psychosocial functioning. Their executive performance was assessed using neuropsychological tests. Regression analyses were carried out in the regions in which volume differences were detected. Decreases in gray matter were detected bilaterally in alcohol-dependents in the dorsolateral frontal cortex (up to 20% lower), and to a lesser extent in the temporal cortex, insula, thalamus, and cerebellum. Decreases in white matter volume were widespread, being up to 10% in corpus callosum. The degradation of neuropsychological performance correlated with gray matter volume decreases in the frontal lobe, insula, hippocampus, thalami and cerebellum, and with white matter decrease in the brainstem. An early age at first drinking was associated with decreased gray matter volumes in the cerebellum, brainstem (pons), and frontal regions. Regional alteration in gray and white matter volume was associated with impairment of executive function despite preserved social and somatic functioning in detoxified patients. Besides involving frontal regions, these findings are consistent with a cerebello-thalamo-cortical model of impaired executive functions in alcohol-dependent individuals.

Alcoholism↗

PubMed2006

Left superior temporal gyrus activation during sentence perception negatively correlates with auditory hallucination severity in schizophrenia patients.

The left superior temporal cortex, which supports linguistic functions, has consistently been reported to activate during auditory-verbal hallucinations in schizophrenia patients. It has been suggested that auditory hallucinations and the processing of normal external speech compete for common neurophysiological resources. We tested the hypothesis of a negative relationship between the clinical severity of hallucinations and local brain activity in posterior linguistic regions while patients were listening to external speech. Fifteen right-handed patients with schizophrenia and daily auditory hallucinations for at least 3 months were studied with event-related fMRI while listening to sentences in French or to silence. Severity of hallucinations, assessed using the auditory hallucination subscales of the Psychotic Symptom Rating Scales (PSYRATS) and of the Scale for the Assessment of Positive Symptoms (SAPS-AH), negatively correlated with activation in the left temporal superior region in the French minus silence condition. This finding supports the hypothesis that auditory hallucinations compete with normal external speech for processing sites within the temporal cortex in schizophrenia.

Adult↗

PubMed2006

Paracingulate sulcus morphology and fMRI activation detection in schizophrenia patients.

OBJECTIVE: Altered anterior cingulate cortex activity has been consistently detected by functional imaging in schizophrenia patients. In the present study, we hypothesized that the detection of such local hypoactivity varies when the subjects' local gyrification is monitored. Using a group-statistical approach, we investigated whether the presence or absence of a paracingulate sulcus (PCS) does influence the detection of the activation patterns in the cognitive division of the anterior cingulate cortex (ACcd). METHOD: fMRI data were acquired using an event-related paradigm during a task involving both priming and interference between stimuli. In the fMRI dataset collected from 13 schizophrenia patients and 16 healthy subjects, subgroups were defined according to the presence or absence of a PCS. Regional activations during interference between stimuli were examined in the ACcd of each hemisphere, using for each region of interest both voxel-based random-effects and non-parametric analyses. RESULTS: ACcd activation was left-sided in healthy subjects with a PCS, and right-sided in healthy subjects devoid of a PCS. ACcd activations were detected bilaterally in schizophrenia patients with a PCS, whereas left ACcd was deactivated in patients without a PCS. Subgroup comparisons revealed no difference between healthy subjects with a PCS and patients with a PCS, whereas in the subgroups devoid of PCS, the patients exhibited a bilateral ACcd hypoactivation relative to healthy subjects. CONCLUSIONS: PCS presence or absence influences the detection of ACcd activations in group-analysis of schizophrenia patients.

Adult↗

PubMed2005

Cognitive control in childhood-onset obsessive-compulsive disorder: a functional MRI study.

BACKGROUND: Failure to resist chronic obsessive-compulsive symptoms may denote an altered state of cognitive control. We searched for the cerebral regions engaged in this dysfunction. METHOD: Differences in brain regional activity were examined by event-related functional magnetic regional imaging (fMRI) in a group of adolescents or young adults (n = 12) with childhood-onset obsessive-compulsive disorder (OCD), relative to healthy subjects. Subjects performed a conflict task involving the presentation of two consecutive and possibly conflicting prime and target numbers. Patients' image dataset was further analysed according to resistance or non-resistance to symptoms during the scans. RESULTS: Using volume correction based on a priori hypotheses, an exploratory analysis revealed that, within the prime-target repetition condition, the OCD subjects activated more than healthy subjects a subregion of the anterior cingulate gyrus and the left parietal lobe. Furthermore, compared with 'resistant' patients, the 'non-resistant' OCD subjects activated a bilateral network including the precuneus, pulvinar and paracentral lobules. CONCLUSIONS: Higher regional activations suggest an abnormal amplification process in OCD subjects during the discrimination of repetitive visual stimuli. The regional distribution of functional changes may vary with the patients' ability to resist obsessions.

Adult↗

PubMed2003

Conscious and subliminal conflicts in normal subjects and patients with schizophrenia: the role of the anterior cingulate.

The human anterior cingulate cortex (ACC), which is active during conflict-monitoring tasks, is thought to participate with prefrontal cortices in a distributed network for conscious self-regulation. This hypothesis predicts that conflict-related ACC activation should occur only when the conflicting stimuli are consciously perceived. To dissociate conflict from consciousness, we measured the behavioral and brain imaging correlates of a motor conflict induced by task-irrelevant subliminal or conscious primes. The same task was studied in normal subjects and in patients with schizophrenia in whom the ACC and prefrontal cortex are thought to be dysfunctional. Conscious, but not subliminal, conflict affected anterior cingulate activity in normal subjects. Furthermore, patients with schizophrenia, who exhibited a hypoactivation of the ACC and other frontal, temporal, hippocampal, and striatal sites, showed impaired conscious priming but normal subliminal priming. Those findings suggest that subliminal conflicts are resolved without ACC contribution and that the ACC participates in a distributed conscious control network that is altered in schizophrenia.

Adolescent↗

PubMed2003

Paracingulate sulcus morphology in men with early-onset schizophrenia.

BACKGROUND: Cingulate dysfunction has been reported in schizophrenia. Although the paracingulate sulcus (PCS) is known to be asymmetric in healthy people, little information is available about its morphology in schizophrenia. AIMS: To search for morphological anomalies of the PCS in men with early-onset schizophrenia. METHOD: The PCS was examined in magnetic resonance images of the brains of men with schizophrenia and 100 healthy men. RESULTS: A significant asymmetry was found in the brains of healthy volunteers, whose sulci were more frequent and more marked in the left hemisphere. In contrast, the sulcus was as frequent in the right as in the left hemisphere in the patient group. Moreover, patients displayed significantly more rightward asymmetry, and overall less-asymmetrical patterns than the comparison group. CONCLUSIONS: Since the PCS has developed at 36 weeks of gestation, these findings suggest an impaired maturation of the cingulate region during the third trimester.

Adult↗

PubMed2002

Effect of impaired recognition and expression of emotions on frontocingulate cortices: an fMRI study of men with alexithymia.

OBJECTIVE: Although the brain areas involved in emotional response and in the recognition of others' emotions have been reported, the neural bases of individual differences in affective style remain to be elucidated. Alexithymia, i.e., impairment of the ability to identify and communicate one's emotional state, influences how emotions are regulated. Alexithymia has been hypothesized to involve anterior cingulate dysfunction. Therefore, the authors searched for differential cerebral regional activation in response to emotional stimuli in subjects with alexithymia. METHOD: Two groups of eight men each were selected from 437 healthy subjects on the basis of high or low scores on the 20-item Toronto Alexithymia Scale. Using functional magnetic resonance imaging (fMRI), the authors compared the two groups for their regional cerebral activation in response to the presentation of pictures with validated positive or negative arousal capabilities. RESULTS: Men with alexithymia demonstrated less cerebral activation in the left mediofrontal-paracingulate cortex in response to highly negative stimuli and more activation in the anterior cingulate, mediofrontal cortex, and middle frontal gyrus in response to highly positive stimuli than men without alexithymia. CONCLUSIONS: These findings provide direct evidence that alexithymia, a personality trait playing a role in affect regulation, is linked with differences in anterior cingulate and mediofrontal activity during emotional stimuli processing.

Adult↗

PubMed2002

[Brain imaging and eating disorders].

Among the brain imaging studies that have been conducted in eating disorder patients, some focused on the morphological alterations associated with these disorders, and others aimed at investigating functional cerebral alterations of these patients. However, very few studied the links between the observed morphological and functional alterations and cognitive functioning of these patients more specifically. Here we report the results provided by the various brain neuroimaging techniques that were used to assess brain structure and functioning, and neuroendocrine dysregulation of eating disorders patients. A number of abnormalities evidenced by neuroimaging studies, notably the structural ones, do not seem completely reversible with clinical improvement. This article stresses the need for more imaging studies examining to which extent these alterations are reversible. Based on animal and human literature describing the neural bases of eating behavior, that highlight potential pathophysiological mechanisms that may be involved in the etiology of eating disorders, we will try to determine how understanding eating disorders pathophysiology could benefit from the use of neuroimaging.

Animals↗