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B N'Kaoua

Publications and source records attributed to B N'Kaoua.

10 recordsLinked to original sources
PubMed2004

Verbal fluency output in children aged 7-16 as a function of the production criterion: qualitative analysis of clustering, switching processes, and semantic network exploitation.

Developmental changes in children's verbal fluency were explored in this study. One hundred and forty children aged from 7 to 16 completed four verbal fluency tasks, each with a different the production criterion (letter, sound, semantic, and free). The age differences were analyzed both in terms of number of words produced, and clustering, switching, and semantic network exploration. Analysis of the number of words produced showed a larger difference between the 7-8- and the 9-10-year-olds in semantic than in letter fluency, but this difference gradually disappeared with increasing age for semantic fluency while remaining constant for letter fluency. In letter fluency production, age modified both the number of switches and clusters formed whereas in semantic fluency tasks, only cluster size changed with age. Concerning the semantic network exploration indicators derived from the supermarket fluency task, the number of categories sampled increased from 11 to 12 years, but efficient semantic exploitation occurred only after the age of 13-14 years. These results are discussed in terms of the development of strategic retrieval components and categorical knowledge.

Adolescent↗
PubMed2001

Exploration of hemispheric specialization and lexico-semantic processing in unilateral temporal lobe epilepsy with verbal fluency tasks.

Verbal production has been shown to rely on both hemispheres differentially. To determine how lateralized brain lesions affect the generation of isolated words, we evaluated three subject groups: normal controls (n=22), and patients with right (n=23), and left (n=22) non-operated temporal lobe epilepsy (TLE) using three verbal fluency tasks (letter, phonetic, semantic). LTLE patients produced fewer words than controls in the phonetic, letter, semantic conditions, whereas RTLE patients were only impaired in the semantic task. Hence, there would be a hemispheric specialization in language where phonetic processing involves mostly the left temporal lobe and semantic aspects of production involve both temporal lobes. And, in order to study disruption of semantic lexicon involved in supermarket fluency (to name things which can be bought in a supermarket), specific indicators Tröster et al., (1998) [Tröster AI, Fields JA, Testa JA, Paul RH, Blanco CR, Hames KA, Salmon DP, Beatty WW. Cortical and subcortical influences on clustering and switching in the performance of verbal fluency Tasks, Neuropsychologia 1998;36:295-304.] were exploited. Our results indicated that TLE groups made fewer category shifts than controls. Also, RTLE patients used labels more frequently and produced fewer exemplars. Results show the specificity of processing according to cue, and suggest that the semantic fluency deficits due to TLE be primarily due to an alteration of the mental lexicon.

Adult↗
PubMed1998

Location of the epileptic zone and its physiopathological effects on memory-related activity of the temporal lobe structures: a study with intracranial event-related potentials.

PURPOSE: Neuropsychological research with epileptic patients has suggested that the location of seizure focus may be an important variable determining the nature and severity of memory impairments. According to this assumption, this study was designed to investigate the effects of the location of the epileptic zone on the memory-related activity recorded directly from different temporal lobe structures. METHODS: Intracranial event-related potentials (ERPs) were recorded during a continuous recognition memory task, which is known to elicit the modulation of N400 and P600 components (i.e., the ERP old/new effect). The patients were separated into three groups according to the location of their epileptic zone: unilateral temporal (UTE), temporal plus extratemporal (TEE), and bitemporal (BTE). Recordings were obtained from three temporal lobe structures: hippocampus, amygdala, and lateral temporal cortex. RESULTS: The results showed that in the hippocampus, the ERP old/new effect was abolished in the TEE group only. In the amygdala, although largely unaffected, the ERP modulation appeared to be more impaired in UTE patients. Contrasting with these data is the observation that the magnitude and reliability of the ERP old/new effect recorded at the neocortical level increases as the epileptic zone extends to the temporal lobes (i.e., BTE>TEE>UTE). CONCLUSIONS: It is concluded that the memory-related activity modulation of memory ERPs recorded from different temporal lobe structures is affected differently by the presence of an epileptic zone as a function of its location. The possible clinical implications of these findings in surgery planning are also discussed.

Adolescent↗
PubMed1996

Differential involvement of the human temporal lobe structures in short- and long-term memory processes assessed by intracranial ERPs.

Intracranial event-related potentials (ERPs) elicited during a recognition memory task were recorded in 25 epileptic patients by using depth electrodes sampling four different regions within the temporal lobe (amygdala, hippocampus, anterior and posterior temporal cortices). The task was a continuous recognition memory task in which repeated items were presented after 6 or 19 intervening items following their first presentation. This study was performed to investigate the respective role of the different temporal lobe structures in short-term memory (STM) and long-term memory (LTM) processing. Subregions of the temporal lobe were differently involved in these two memory systems. The posterior temporal cortex is specifically involved in STM processing, whereas the amygdala, hippocampus, and anterior temporal cortex contribute to both STM and LTM. Moreover, it appeared that the latter structures play their own role in LTM. The anterior temporal cortex and amygdala may contribute to recency discrimination, and the hippocampus seems rather to be involved in maintaining memory traces. These findings suggest that the temporal lobe structures may function in a complementary way by subserving different aspects of information processing.

Adolescent↗
PubMed1995

Effects of temporal versus temporal plus extra-temporal lobe epilepsies on hippocampal ERPs: physiopathological implications for recognition memory studies in humans.

The present experiment was designed to investigate the incidence of temporal and extra-temporal epileptogenic lesions on hippocampal activity related to recognition memory. Hippocampal event-related potentials (ERPs) were recorded during a recognition memory task for pictures in patients with unilateral temporal lobe epilepsy and in patients with combined temporal and extra-temporal (frontal or parietal) epileptogenic foci. In the first group, the comparison between correctly recognized pictures and new distractors revealed that the usual ERP (N400/P600) 'old/new' effects were not dramatically affected by the presence of a temporal epileptogenic lesion. In contrast, these effects were absent in multifocal epilepsy patients, indicating that frontal and parietal brain regions play a part in the modulation of hippocampal ERP and related memory processing. These results suggest that ERP 'old/new' effects are dependent on interactions between frontal, parietal and medial temporal structures. Together with the results of other recent studies devoted to locating the neural sources of N400 and P600, the present findings provide physiopathological evidence that ERP 'old/new' effects are subtended by distributed yet interconnected brain regions that are known to play an important role in recognition memory processing.

Adult↗
PubMed1995

Intracranial topography of event-related potentials (N400/P600) elicited during a continuous recognition memory task.

To isolate the anatomical locus of the neural activity most important for generating or modulating the scalp-recorded N400 and P600 components elicited during continuous recognition memory tasks, intracranial event-related potentials (ERPs) were recorded from medial and lateral aspects of the temporal, frontal, parietal, and occipital lobes in 25 patients undergoing stereoelectroencephalography for seizure localization. Large-amplitude and polarity-inverted ERPs were recorded from various temporal, frontal, and parietal structures, whereas the memory-related ERP modulation assessed by the ERP repetition effect was present only in those brain areas that play the most important role in memory processing. These data suggest that the scalp-recorded N400 and P600 components may represent the most readily observable aspect of synchronous activity occurring across widely distributed brain structures and neural systems underlying different cognitive mechanisms, which all contribute to some aspect of information processing during recognition memory.

Adolescent↗
PubMed1991

[P3on and P3off in a passive visual protocol].

This study shows the possibility of obtaining visual event-related potentials without active discrimination instructions. The components are similar to the P3 components obtained in classic active protocol. The (P3off) of simple images indicates an interpretation in terms of information processing and change in mental state.

Adult↗
PubMed1990

[Cerebral psychophysiologic study of the processes brought into action by physical context modifications in the short-term recognition of images].

The study of P300 waves and reaction times during the acquisition and recognition of simple symbolic pictures (Signoret's test) shows the extent of "contextual effect" in visual short-term recognition. These results support the "encodage spécifique" theory according to which contextual changes between acquisition and restitution reduce memory efficiency.

Adult↗
PubMed1989

[P 300 wave and additive or self-terminated processes in short-term image recognition].

The study of the P 300 wave during the acquisition and the recognition of simple symbolic pictures shows a self-terminated treatment in short-term visual recognition processes. The results of this study plead in favour of a general principle of psychobiological economy and of a decrease of the mental charge. This principle is at variance with one of the postulates of Sternberg's additive processes theory.

Adult↗