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J Delacour

Publications and source records attributed to J Delacour.

17 recordsLinked to original sources
PubMed1992

The Roman strains of rats as a psychogenetic tool for pharmacological investigation of working memory: example with RU 41656.

This study examined the effects of RU 41656, a dopaminergic D2 agonist, on the differential working memory performances and on the differential activities of the neurochemical systems of the Roman high (RHA) and Roman low (RLA) avoidance strains of rats. Compared with RLA, RHA performed worse in three tests of working memory (spontaneous alternation, radial maze and object recognition) and had higher levels of exploratory locomotor activity. Hippocampal and frontal cortex choline acetyltransferase (ChAT) activities were lower in RHA. Frontal cortex DA and DOPAC levels, hippocampal and striatal 5-HT and NA levels were higher in RHA. RU 41656 induced a significant improvement in working memory performance of RHA, whereas in RLA it had no effect. It decreased exploratory locomotor activity in both strains. ChAT activity in hippocampus was not affected by RU 41656 in either strain, whereas in frontal cortex it was increased in RHA but not in RLA. Hippocampal NA levels were decreased by RU 41656 in RHA but not in RLA. These results confirm previous data concerning the promnesic effect of RU 41656 and extend the finding that the Roman strains are a psychogenetic model for the behavioural, neurochemical and psychopharmacological study of the working memory in rats.

Animals↗
PubMed1991

Contribution of the Roman strains of rats to the elaboration of animal models of memory.

Performances of male rats of the Roman High (RHA)- and Roman Low (RLA)-Avoidance strains were compared along four essential dimensions: working memory, reference memory, spontaneous locomotion and avoidance conditioning. Performances of RLA and RHA rats were significantly different for each dimension. As constantly reported, RHA rats were by far superior to RLA in avoidance conditioning. They had also higher levels of locomotor activity. On the opposite, RLA performed better than RHA in an appetitive working memory task, the delayed reinforced alternation, and were also superior in an appetitive reference memory task, the 5-unit linear maze. These results confirm the fact that RLA rats may acquire positively reinforced learning more rapidly than RHA rats and that the differences in active avoidance behavior between the two strains depend more on differential freezing behavior than on learning or memory capacities. Beyond the problem of the characterization of the Roman strains, these data might give indications on the relationships between behavioral tests widely used in rats, and on their use as memory models.

Animals↗
PubMed1991

Roman strains as a psychogenetic model for the study of working memory: behavioral and biochemical data.

Performances of male rats of the Roman High- (RHA), Roman Control- (RCA) and Roman Low- (RLA) Avoidance strains were compared in two working memory tests, a spatial one, the radial maze, and a nonspatial one, an object recognition test. The same rats were subjected to measures of emotional reactivity and of different forms of motor activity and finally to measures of cholinergic and aminergic activities in the hippocampus, frontal cortex and striatum. Compared to RHA, RLA performed better in the two working memory tests, displayed "anxiety" and had also lower levels of exploratory locomotor activity. Hippocampal ChAT activity was higher in RLA than in RHA. Levels of DA and DOPAC in the striatum were higher in RLA compared to RHA, whereas in the frontal cortex they were lower. For most of these measures, RCA were intermediate between RLA and RHA. These results confirm and extend the finding that the Roman strains are not only a genetic model for two-way avoidance conditioning but also for working memory.

Animals↗
PubMed1991

Selective fimbria and thalamic lesions differentially impair forms of working memory in rats.

Several series of experiments were designed to compare the effects of selective lesions of the fimbria or of thalamic nuclei on three different tasks involving working memory in rats: object recognition, place recognition, and the radial arm maze test. The main effects of fimbria lesions were as follows: they produced deficits in the radial maze; object recognition was spared or even facilitated, whereas place recognition was impaired. Electrolytic lesions of either centromedian-parafascicularis (CM-Pf) or dorsomedialis (DM) nuclei produced highly significant deficits in the radial maze test but spared object and place recognition. Ibotenate lesions of the CM-Pf had no effect on any test, which means that the critical structure in the effects of the electrolytic lesions of the CM-Pf was the fasciculus retroflexus (FR). These data may contribute two main points to animal models of hippocampal and thalamic amnesia: (1) different forms of working memory in rats might have different neural bases and (2) the FR may be involved in learning and memory processes.

Animals↗
PubMed1978

[Experimental dissociation between hippocampal theta activity in wakefulness and hippocampal theta activity in paradoxal sleep in the rat].

The effects of electrolytic lesion of the septum on the theta activity of the dorsal hippocampus were studied in the chronically implanted Rat during wakefulness and paradoxical sleep. The experimental results show that depending on its localization, septal lesion can either: (1) eliminate the wakefulness theta rhythm without suppressing that of paradoxical sleep; (2) eliminate the paradoxical sleep theta rhythm without suppressing that of wakefulness. These results suggest that there are two kinds of theta activity having different anatomophysiological bases and a different functional significance: one associated with wakefulness and the other with paradoxical sleep.

Animals↗
PubMed1978

[Effects of bilateral dorsolateral pontine tegmentum lesions on hippocampus theta rhythm during paradoxical sleep in the rat].

Electrolytic lesions of the dorsolateral pontine tegmentum aimed at the locus coeruleus (LC) were performed bilaterally in 13 chronically implanted Rats. Following lesions, transient alterations of characteristic components of theta rhythm appeared. No shortening of duration of paradoxical sleep (PS) was observed. These results do not support the hypothesis that neurons of LC are directly involved in the production of theta rhythm during PS; moreover they seem not to be necessary to the normal appearance of this state of sleep.

Animals↗
PubMed1977

[Inferotemporal cortex and short term visual memory in monkeys. New data].

The effects of bilateral electrical stimulation of inferotemporal cotex on matching to sample were studied in four monkeys. Each session was defined by four different factors. 1. Number of stimuli: the same pair of stimuli (one-pair condition, OP) or a different pair of stimuli (multi-pair condition, MP) was used, from trail to trial. 2. Location of stimulation: anterior inferotemporal cortex (ITA) or posterior inferotemporal cortex (ITP). 3. No intra-trial delay (simultaneous match to sample, SMS) or 5-secintra-trial delay (delayed match to sample, DMS). 4. Period of stimulation: sample resentation, delay or match period. Stimulation had no effect on SMS in all the combinations of the three other factors. ITP or ITA stimulation had no effect on DMS when applied during the delay, in OP and in MP condition. ITP stimulation during the sample resentation produced a significant deficit in OP and MP condition. ITA stimulation during the match period produced a significant deficit in OP but not in MP condition.

Animals↗
PubMed1977

[Ontogenetic analysis of the theta rhythm during paradoxical sleep in rats].

In the rat, an ontogenetic study of theta rhythm during paradoxical sleep shows a clear evolution between the 14th and the 30th postnatal day. During this period, its mean frequency increases from 5 to 7 cycles per second, and its spectrum shows significant changes. These parameters (mean frequency and spectral components) of the theta rhythm could be a useful index of brain maturation in the rat.

Animals↗
PubMed1977

Specificity of avoidance deficits produced by 6-hydroxydopamine lesions of the nigrostriatal system of the rat.

Microinjections of 6-hydroxydopamine (6-OHDA) into the dopaminergic nigrostriatal system (NS) of the rat impaired acquisition of a two-way avoidance response. This effect was independent of nutritional deficiencies since it was observed even when a special postoperative treatment ensured a comparable state of nutrition in control and experimental rats. It was likewise independent of locomotor disturbances. A third question remains open: Doses of 6-OHDA that impaired acquisition of an active avoidance response produced lesions that were, to a great extent, nonspecific. Therefore, behavioral effects of these doses cannot be entirely ascribed to selective destruction of the NS.

Animals↗
PubMed1976

[Statistical relationship between "slow-wave sleep" and "paradoxical sleep" in rats].

In the Rat, statistical analysis of slow sleep (SS) and paradoxical sleep (PS) episodes disclosed two significant (p less than 0,01) positive correlations: (1) Over a four-hour period, the mean duration of PS episodes was correlated to the mean of the just preceding "light" SS episodes; (2) On the contrary, from cycle to cycle of sleep-wakefulness, the duration of each PS episode was correlated to that of the "light" SS episode of the next cycle.

Animals↗
PubMed1975

An analysis of short-term visual memory in the monkey.

Visual memory in monkeys was examined under four different conditions, each with a separate group. In all conditions, the delay between sample and choice was 10 sec, and the delay between trials was 30 sec. The procedural differences were matching or nonmatching with the same two objects presented repeatedly and matching or nonmatching with trial-unique objects. With the customary repetitive stimuli, whether in matching or nonmatching, most monkeys either required prolonged training to solve the problem (over 40 sessions) or failed to solve it, corroborating the learning difficulties reported earlier by others. With trial-unique stimuli, by contrast, most monkeys learned quickly (matching, under 20 sessions; nonmatching, under 5 sessions). Furthermore, in nonmatching with trial-unique stimuli, scores averaged 80% correct in the first session, even though the monkeys were experimentally naive. The results indicate that recognition of a stimulus as familiar or novel is highly developed in monkeys, and that their difficulty with the customary nonspatial visual memory tasks stems from a retardation in noticing and using the mnemonic cue of recovery of presentation. Evidence is presented that this difficulty can be overcome, however, by a simple training procedure that exploits their proficiency at distinguishing familiar from novel stimuli.

Animals↗