Search results for "Potentials"
showing 10 items of 1072 documents
Cannabinoid type 1 receptor modulates intestinal propulsion by an attenuation of intestinal motor responses within the myenteric part of the peristal…
2007
Cannabinoid-1 (CB1) receptor activation affects gastrointestinal propulsion in vivo. It was our aim to further characterize the involved myenteric mechanisms in vivo and in vitro. In CB1(-/-) mice and wild-type littermates we performed in vivo transit experiments by charcoal feeding and in vitro electrophysiological recordings in mouse small intestinal smooth muscle. Ascending neuronal contraction (ANC) following electrical field stimulation was studied in rat ileum in a partitioned organ bath separating the aboral stimulation site from the oral recording site. The knockout animals displayed an accelerated upper gastrointestinal transit compared to control animals. The CB1 receptor antagoni…
Les compléments neurophysiologiques du diagnostic
2009
Les recherches presentees mettent en evidence des relations entre anomalies comportementales et cognitives et dysfonctionnements cerebraux sous-jacents a partir de methodes d'exploration electrophysiologique non invasives (electroencephalogramme, potentiels evoques auditifs). Trois types de troubles sont etudies : les troubles du sommeil, l'intolerance au changement et l'exploration visuelle atypique des visages humains. La complementarite des approches cliniques et neurophysiologiques est cruciale aux etapes du diagnostic fonctionnel, de l'intervention therapeutique et educative.
Factors affecting basket catheter detection of real and phantom rotors in the atria: A computational study
2018
[EN] Anatomically based procedures to ablate atrial fibrillation (AF) are often successful in terminating paroxysmal AF. However, the ability to terminate persistent AF remains disappointing. New mechanistic approaches use multiple-electrode basket catheter mapping to localize and target AF drivers in the form of rotors but significant concerns remain about their accuracy. We aimed to evaluate how electrode-endocardium distance, far-field sources and inter-electrode distance affect the accuracy of localizing rotors. Sustained rotor activation of the atria was simulated numerically and mapped using a virtual basket catheter with varying electrode densities placed at different positions withi…
Rapid developmental switch in the mechanisms driving early cortical columnar networks
2006
The immature cerebral cortex self-organizes into local neuronal clusters long before it is activated by patterned sensory inputs. In the cortical anlage of newborn mammals, neurons coassemble through electrical or chemical synapses either spontaneously or by activation of transmitter-gated receptors. The neuronal network and the cellular mechanisms underlying this cortical self-organization process during early development are not completely understood. Here we show in an intact in vitro preparation of the immature mouse cerebral cortex that neurons are functionally coupled in local clusters by means of propagating network oscillations in the beta frequency range. In the newborn mouse, this…
Rhythmic variations in reaction times and evoked potentials
1995
The present work aimed to assess the existence of a regular ultradian cyclicity underlying the variations in amplitude of the N1-P2 component of acoustic EP during a relatively long recording session and investigate its relationship with behavioral measure as RT to the same stimulus. 128 tones were presented to each subject; 128 RTs and the associated EPs to target stimuli were recorded. N1-P2 amplitude has been measured at a single trial level through Woody adaptive filter modified by Wastell. Results showed that there are ultradian rhythmic variations of N1-P2 and RT, with a periodicity from about 5 to 40 min and these variations have similar patterns in the two measures in most of the su…
Physiological and metabolic actions of mycophenolate mofetil on cultured newborn rat cardiomyocytes in normoxia and in simulated ischemia
2004
Mycophenolate mofetil (MMF) is a new immunosuppressive drug used to reduce acute rejection after heart transplantation. As with other immunosuppressive drugs, MMF therapy is associated with several adverse effects. However, the direct effects of MMF on myocardial tissue has not been yet evaluated. The aim of the work was thus to evaluate the effects of MMF on isolated cardiomyocytes (CM) in normal conditions and in an in vitro model of simulated ischemia (SI; substrate-free hypoxia) and reperfusion (R; reoxygenation). Myocyte-enriched cultures were prepared from newborn rat heart ventricles. The transmembrane potentials were recorded using conventional microelectrodes and the cell contracti…
SINGLE-TRIAL BASED INDEPENDENT COMPONENT ANALYSIS ON MISMATCH NEGATIVITY IN CHILDREN
2010
Independent component analysis (ICA) does not follow the superposition rule. This motivates us to study a negative event-related potential — mismatch negativity (MMN) estimated by the single-trial based ICA (sICA) and averaged trace based ICA (aICA), respectively. To sICA, an optimal digital filter (ODF) was used to remove low-frequency noise. As a result, this study demonstrates that the performance of the sICA+ODF and aICA could be different. Moreover, MMN under sICA+ODF fits better with the theoretical expectation, i.e., larger deviant elicits larger MMN peak amplitude.
Auditory Event-Related Potentials in the Study of Developmental Language-Related Disorders
1997
This article reviews recent auditory event-related potential (ERP) studies of developmental language disorder (DLD) and dyslexia/reading disorder (RD). The possibility of using ERPs in searching for precursors of these disorders in the early development of infants at risk is also discussed. Differences in exogenous/sensory ERPs at the latency range of P1 and N1-P2 components have been reported between groups with DLD and RD and control groups. Latency differences between the groups may be related to a common timing deficit suggested by some researchers to be one of the possible underlying factors both in DLD and dyslexia. N1 amplitude group differences may be partly related to arousal/atten…
Deaf readers benefit from lexical feedback during orthographic processing
2019
Published: 23 August 2019 It has been proposed that poor reading abilities in deaf readers might be related to weak connections between the orthographic and lexical-semantic levels of processing. Here we used event related potentials (ERPs), known for their excellent time resolution, to examine whether lexical feedback modulates early orthographic processing. Twenty congenitally deaf readers made lexical decisions to target words and pseudowords. Each of those target stimuli could be preceded by a briefly presented matched-case or mismatched-case identity prime (e.g., ALTAR-ALTAR vs. altar- ALTAR). Results showed an early effect of case overlap at the N/P150 for all targets. Critically, thi…
Mismatch negativity (MMN) as a tool for investigating auditory discrimination and sensory memory in infants and children
2000
For decades behavioral methods, such as the head-turning or sucking paradigms, have been the primary methods to investigate auditory discrimination, learning and the function of sensory memory in infancy and early childhood. During recent years, however, a new method for investigating these issues in children has emerged. This method makes use of the mismatch negativity (MMN), the brain's automatic change-detection response, which has been used intensively in both basic and clinical studies in adults for twenty years. This review demonstrates that, unlike many other components of event-related potentials, the MMN is developmentally quite stable and can be obtained even from pre-term infants…