Biomedical subjects

B Claverie

Publications and source records attributed to B Claverie.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Functional heterogeneity of the frontal lobe: evidence from intracranial memory ERPs.

Intracranial event-related potentials (ERPs) elicited during a recognition memory task were recorded in 17 epileptic patients by using depth electrodes sampling different regions within the frontal lobe. The task was a continuous recognition memory task in which repeated items were presented after six or 19 intervening items following their first presentation. Such a paradigm is one of the experimental tasks requiring both short-term memory and interference control processes which are thought to be subserved by the frontal lobe. The results provide electrophysiological support for the classical view that the frontal lobe is heterogeneous region encompassing a number of functional systems subserving different aspects of memory processing. The anterior dorsolateral and cingulate cortices were found to contribute to short-term memory and recency judgment. The orbital region is more likely to be involved in interference control. The posterior part of the frontal cortex plays a role in some processes related to the control of the motor response.

Adult↗

PubMedDate not supplied

[Emotional and attentive interferences and slow cerebral potentials (CNV-P 300) (author's transl)].

A study was conducted to establish possible correlations between electrophysiological indices and performance under neutral situations and those involving completing a double task of increasing complexity, by studying CNV and P 300 in young healthy men. The results demonstrated that: 1. After habituation, the CNV amplitudes were not related to performance. A significant correlation was noted only during the most complex tasks. 2. The CNV appears to depend mainly on endogenous factors, that is to say the aptitude and readiness of an individual to treat the information, rather than on the performance resulting from this treatment. 3. The amplitude of the P 300 is related to performance, as a function of detection rate and the complexity of the tasks. The functional duality of the CNV and the differences between it and the P 300 have been emphasized. The indices obtained from slow potentials appear to be of value for an evaluation of behaviour. Rather than analyzing the characteristics of the potentials in a supposedly "neutral" situation it would appear preferable to establish, from the indices, profiles of individual reactivity and adaptation to different experimental situations.

Action Potentials↗

PubMedDate not supplied

[Visual evoked potentials in elderly subjects (author's transl)].

Study of visual evoked potentials by contrast stimuli (VEPL) and by luminance stimuli (VEPC) in 28 subjects aged between 65 and 95 years (mean age: 81.8 years). Changes related to aging in regard to VEP involve: an increase of latencies of VEPL affecting the early components and an increase in the maximum amplitude of VEPL. The course of EP as age progresses introduces a difference in topographical organisation with a deterioration of responses in the left occipital regions and a change in potentials recorded at the vertex. Aging would appear to cause more marked inter-individual differences which could have clinical implications by making it possible to demonstrate individual differences in the biological processes of aging.

Aged↗

PubMedDate not supplied

Age effect in recall performance according to the levels of processing, elaboration, and retrieval cues.

The present study was conducted to investigate the incidence of several factors contributing to age-related memory decrement. Variables manipulated include quality (level of processing encoding conditions), the degree of effort and encoding quantitative elaboration (active/passive encoding conditions), and the influence of retrieval support (free-/cued recall conditions). In support of the environmental support hypothesis, middle-old and old subjects benefited more than young ones from cued recall in all the memory tests. Moreover, the results showed a differential (qualitative vs. quantitative) impairment of conceptual processing between the middle-old and the old-age groups. In the middle-olds, age differences were abolished by deep processing in old adults, age differences were attentuated only with deep and active processing associated with retrieval support. These gradual memory impairments are evaluated according to Mandler's model of memory (1979, In L. G. Nilsson [Ed.], Perspective in memory research. Hillsdale: Lawrence-Erlbaum), and the environmental support hypothesis is discussed in terms of the involvement of encoding and retrieval operations required by the memory task.

Adult↗