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Biomedical subjects

M Gauthier

Publications and source records attributed to M Gauthier.

At least 127 records · Page 7Linked to original sources
PubMed1983

Functional dissociation between lateral and medial entorhinal cortex in memory processes in mice.

The effects of lesions of the medial or the lateral entorhinal cortex in mice were examined on acquisition, retention and extinction of an operant-conditioning task in a Skinner box. Compared with the control animals, lesions in the medial entorhinal had no behavioral effects whereas lesions in the lateral entorhinal enhanced retention and increased resistance to extinction but did not change acquisition of this task. These results suggest a functional dissociation between the two parts of the entorhinal cortex.

Animals↗
PubMed1982

Late post-learning participation of entorhinal cortex in memory processes.

Mice of the BALB/c strain were bilaterally implanted with electrodes in the lateral entorhinal cortex (EC) in order to study the influence of post-trial EC stimulation on memory. The learning task was a food reinforced operant conditioning. At one of several time intervals after a first learning session, the experimental groups were stimulated for 80 s with subseizure current intensity. Testing was carried out 24 h later. In the first experiment, a continuous reinforcement schedule was used. EC stimulation had no effect when applied at the 30-s or 3-h intervals, but surprisingly a 30-min delayed stimulation greatly improved retention compared to performance of non-stimulated animals. In the second experiment, the same paradigm was used in a discriminative operant conditioning task. The same facilitation on retention was observed only with the 30-min delayed stimulation. Compared to previous data with hippocampal or hypothalamic stimulation, the present results reveal that EC is lately involved in memory processes.

Animals↗
PubMed1981

[Facilitation of the retention and acceleration of operant conditioning extinction after cingulate cortex lesions in BALB/c mice].

One week after receiving bilateral electrolytic lesions of the cingulate cortex, BALB/c Mice underwent acquisition, retention and extinction of an appetitive operant-conditioning task in a Skinner box. There was no significant difference between lesioned and control animals in acquisition; however, lesioned mice exhibited improved retention and faster extinction. These results suggest a possible involvement of the cingulate cortex in memory processes.

Animals↗
PubMed1981

6-Hydroxydopamine and radiofrequency lesions of the lateral entorhinal cortex facilitate an operant appetitive conditioning task in mice.

The entorhinal cortex seems heterogeneous as dopaminergic terminals are present only in the anterior part of the lateral entorhinal cortex. In order to clarify the interaction of this cortex with the hippocampus in memory processes, the effects of either 6-hydroxydopamine or radiofrequency bilateral lesions were compared. Both lesions enhance the retention of a Skinner task with continuous reinforcement schedule. Involvement of dopamine in memory processes is discussed.

Animals↗
PubMed1980

[Memory facilitation induced by delayed electric stimulation of the entorhinal cortex in mice].

A subconvulsive bilateral stimulation of the lateral entorhinal cortex has been applied in BALB/c mice at different time intervals after an appetitive operant conditioning task. 24 hrs later, compared to the control subjects, the performance was improved only in animals stimulated 30 min. after the first learning session. No change was observed in animals stimulated 30 sec. or 3 hrs. post-trial. These results suggest that entorhinal cortex is involved rather late in memory processes.

Animals↗
PubMed1977

[Concentration and method of cadmium fixation by a marine Vibrio].

In many organisms, intracellular fixation of cadmium involves specific proteins, the metallothioneins. A similar phenomenon was demonstrated in a marine bacterium belonging to the genus Vibrio. The accumulation of the metal is a function of its concentration in the medium. The uptake is also increased by cysteine, which decreases the toxicity of the metal.

Bacterial Proteins↗
PubMed1970

The use of jet-injectors in BCG vaccination.

In mass vaccination programmes, the jet-injection of vaccine may have considerable operational advantages over the classical techniques. The technical performance of two models of jet-injector, the Dermo-Jet and the Ped-O-Jet, in BCG vaccination was assessed in a number of studies which are reviewed by the authors. It is shown that the jet-injectors do not administer the full dose for which they are calibrated and that the size of the vaccination lesion varies more than after vaccination by syringe.By increasing the dosage considerably, the results of vaccination by jet-injection may be improved to a certain extent but the risk of unpleasant reactions is also increased.

BCG Vaccine↗