Biomedical subjects

T Jonveaux

Publications and source records attributed to T Jonveaux.

4 recordsLinked to original sources

PubMed2000

[Exploration of visual memory by functional MRI].

PURPOSE: The aim of our study was to evidence the location of the cortical area triggered by visual memory tasks by he mean of functional magnetic resonance imaging examination (fMRI). METHODS: Twelve healthy volunteers underwent fMRI examination on a 1.5 Tesla magnet with echoplanar imaging sequence during figurative and non-figurative memory tasks. An area was considered to be activated if at least 10 contiguous voxels activation was noted. Activated areas were defined for both tasks and the brain mapping was realized according to Talairach atlas. RESULTS: For all examinations a bilateral activity was evidenced (area 17 and 18). In addition, a frontal activation was also noted in 83% of the cases for both tasks. However, frontal activation was bilateral in 9/10 cases for the figurative task and 6/10 cases for the non-figurative task. CONCLUSION: FMRI was able to evidence activation of cerebral areas during visual memory tasks in all our study cases. Frontal activation was not discriminative of figurative or non figurative memory. This might be probably explain by inappropriate non-figurative tests. FMRI should allow a better knowledge of memory mechanisms as well as an enhancement of functional cerebral mapping before surgery.

Adult↗

PubMed1991

[Significance of the blink reflex in the Wallenberg syndrome].

The blink reflex was studied in 38 cases with lateral medullary lesions (Wallenberg syndrome). Twenty-one blink reflexes were abnormal. The most common abnormality is an afferent delay in the late reflex on the side of the lesion with a normal early reflex. This abnormality is not pathognomonic of the Wallenberg syndrome. The physiopathogeny is discussed.

Adult↗

PubMed1991

[Cognitive evoked potentials at the stages II and III of human immunodeficiency virus infection].

Neuropsychological and psychometric investigations have sometimes attested to and sometimes denied the existence of cognitive perturbations during the early phases of human immunodeficiency virus (HIV) infection (stages II and III of the CDC classification): strictly asymptomatic seropositivity or generalized lymphadenopathy. Therein lies the basis of the debate concerning the neurotropism of the virus and its deleterious effects on the central nervous system (CNS). We hoped to contribute to the resolution of this discussion by recording late evoked auditory potentials, which are composed of two types of components: exogenous responses attesting to the reception of stimuli by specific sensory areas of the CNS, regardless of their informative value for the subject; and endogenous responses that occur later, appearing when the subject is required to distinguish between different stimuli, for example, counting high-pitched sounds randomly distributed among low-pitched ones. The latter responses, which have been most extensively studied for wave P300, are associated with cognitive functions, and alterations of the evoked cognitive potentials have been observed during the course of demential syndromes of various origins. Fifteen individuals were subjected to the protocol for recording long-latency, evoked auditory potentials. These studies were completed by a battery of psychometric tests, two methods for evaluating depression and an assessment of the anxiety level. The results showed a significant lengthening of the latency of wave P300 in the seropositive subjects. This prolongation also affected one of the exogenous components, i.e., wave P2. In addition, their intelligence quotients, regardless of whether the IQ explores the so-called crystallized component or the fluid component of intelligence, were not significantly different from those of the general population.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Event-related auditory evoked potentials and multiple sclerosis.

Long latency event-related auditory evoked potentials, particularly the P300 wave, constitute an objective electrophysiological index of cognitive function. For this reason, these potentials have been studied in a series of 101 patients with multiple sclerosis (MS), classified according to McAlpine's criteria into definite, probable and possible cases. The patients were also classified as depressed or non-depressed according to the DSM-III and Research Diagnostic Criteria. They were also subjected to a battery of psychometric tests. In the patient population the N200 and P300 latencies were increased, as were the P200 latencies, when compared with a control population. This electrophysiological pattern had previously been observed in other conditions characterised by subcortical lesions. Partial correlations (at constant disease duration) between the disability score and the cognitive deficit were found to be significant. Patients with an increased P300 latency had a greater disability and the P300 latency was significantly correlated with the duration of the illness. The N200 and P300 latencies were increased in depressed MS subjects, but this increase did not reach the level of significance. Depression was more frequent in the more severely handicapped patients. This suggests that the origin of the depression seen in multiple sclerosis is only partly organic, and that it is one of the factors contributing to the subcortical cognitive deficit in multiple sclerosis. Progressive forms of the disease exhibited the most profound cognitive deficit, and the most marked increase in P300 latency.

Acoustic Stimulation↗