Biomedical subjects

C Pacteau

Publications and source records attributed to C Pacteau.

5 recordsLinked to original sources

PubMed1994

Ventilatory conditioning by self-stimulation in rats: a pilot study.

This article describes an experimental attempt to condition breathing pattern in rats. In this experiment, a freely moving rat was first rewarded by an electrical stimulation of the medial forebrain bundle whenever inspiratory duration (TI) exceeded 300 ms. A bidirectional control was then used: TIs longer than 400 ms were rewarded, and then TIs shorter than 300 ms were rewarded. The frequency of TIs longer than 300 ms increased when this event was rewarded, further increased when TIs above 400 ms were rewarded, and decreased during reversal conditioning (TI < 300 ms). At the beginning of the experiment, stimulation caused increased arousal and motor activity, but after prolonged conditioning, the brain stimulation was associated with quiet wakefulness. Although the general procedure appears to be well-suited to the experimental study of voluntary breathing, some possible improvements are suggested for further, more extensive investigations.

Animals↗

PubMed1994

Measurement of respiratory times in freely moving rats.

A catheter was threaded beneath the skin from the trachea to an opening on the top of the skull. It conducted a small fraction of the ventilatory flow to an external miniaturized transducer, which was composed of a heating element surrounded by two thermocouples. During inspiration, the heating element heated the inner thermocouple, whereas during expiration it heated the outer one. A square signal synchronous with breathing was obtained from the difference in temperature at the two probing sites. Inspiratory and expiratory times were calculated from this signal. This device has been tested with calibrated flows, and compared with head-out plethysmography. It may be easily adapted for ventilatory measurements in any small mammal.

Animals↗

PubMed1993

Abstraction of covariation in category learning: a critical note on K. Richardson's studies.

Several studies directed by K. Richardson (Richardson, 1986, 1987; Richardson & Carthy, 1989, 1990) claimed that people are able to abstract imperfect covariations among feature variables defining artificial categories, and to use that information in various subsequent tasks. We challenge this claim on a twofold basis. First, a large part of the performance variance Richardson attributed to covariation knowledge may be accounted for by a very simple exemplar model, which assumes no abstractive processes. Second, the residual influence of relational information on performance may be attributed to the knowledge subjects have acquired in real-world situations before their training with the study exemplars.

Analysis of Variance↗

PubMed1989

Early rearing environment and dorsal hippocampal ibotenic acid lesions: long-term influences on spatial learning and alternation in the rat.

Behavioural responses in a set of spatial and cue tasks were assessed in adult rats that had been given ibotenic acid lesions of the dorsal hippocampus at weaning. The lesions or sham operations were immediately followed by one month of differential rearing, either in enriched, social or isolated housing environments. The differential rearing was followed by standard (social) housing conditions until behavioural testing began at 4 months of age. Compared to sham-operated rats, the rats with early cytotoxic lesions showed substantial impairments on learning and efficient strategy formation in radial arm maze, retention of a spatial location, but not of a cue-marked location, in a + maze and spontaneous alternation. Differential rearing had some long-term effects depending on the task. Sham-operated rats which had been housed in isolation used a pattern of strategies in the radial arm maze that resembled the pattern used by rats with lesions. Early enrichment, on the other hand, alleviated lesion deficits only in a spontaneous alternation task in a T-maze where the variety and salience of proximal cues were maximised. Enrichment increased lesion deficits in the radial maze task, where distal cues only could guide performance. The results suggest that the hippocampus may play an important role in the use of contextual information and that behavioural recovery after early hippocampal damage--limited to situations in which featural information is highly salient--may be permanently induced by rearing in environments, as in enriched ones, where rats can attend to and manipulate environmental cues.

Animals↗

PubMedDate not supplied

Ethanol intoxication fails to affect sprouting induced by entorhinal cortex lesions.

After unilateral entorhinal cortex lesions, acute ethanol exposure (mean daily intake = 16.3 +/- 0.3 g/kg for 15 days) of juvenile rats failed to alter lesion-induced axonal sprouting in the dentate gyrus. The distribution of acetylcholinesterase in the dentate gyrus was identified histochemically as an indicator of axonal sprouting. Comparisons between operated and intact sides were based on qualitative observations and quantitative morphometry techniques using a computerized image analyser to evaluate the widths of the bands of the molecular layer. Whether ethanol-exposed or not, rats with unilateral entorhinal cortex lesions exhibited substantial qualitative and quantitative evidence of axonal sprouting. These results indicate that a 15-day post-operative ethanol exposure had no effect on axonal sprouting in juvenile rats and thus qualify previous findings about ethanol-mediated effects on axonal sprouting.

Alcoholic Intoxication↗