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Biomedical subjects

J Delacour

Publications and source records attributed to J Delacour.

At least 55 records · Page 3Linked to original sources
PubMed1982

Radioautographic analysis of [14C]2-deoxyglucose uptake in hippocampal formation of the rat during enforced locomotor activity-induced theta.

The [14C]2-deoxyglucose ( [14C]2-DG) uptake in the hippocampal formation of the rat was studied following enforced locomotor activity-induced theta (M theta). M theta was found to be essentially associated with an increase in 2-DG uptake in the stratum oriens of the hippocampal CA1-CA2 areas. These data contrast with our previous findings that physostigmine-induced theta (I theta) is specifically associated with a decrease in 2-DG uptake in the stratum lacunosum moleculare of hippocampal CA1-CA2 areas. When both of our sets of radioautographic data are considered together, M theta and I theta appear to have a distinct neurophysiological basis.

Animals↗
PubMed1982

Behavioural and neurochemical effects of intracerebroventricular administrations of p-octopamine in rats.

Intracerebroventricular administration of p-octopamine (250 micrograms) had opposite effects on locomotor activity of rats depending on whether or not the animals were submitted to electric shocks in the experimental situation. When rats were not shocked, their locomotor activity was significantly decreased by the injection. On the other hand, when rats were trained in a shuttle-box, administration of p-octopamine significantly increased avoidance responding and intertrial crossings. The neurochemical effects of the injections were relatively specific: they significantly increased p-octopamine levels in hypothalamus and brainstem but little effect was observed on noradrenaline and dopamine brain contents. These data suggest that octopamine may play the role of a neuromodulator in the central nervous system of mammals.

Animals↗
PubMed1982

The neocortex of rats behaving in a driven rotating wheel shows a band characterized by preferential uptake of deoxyglucose.

In comparison with control rats placed in a glass chamber, the neocortex of experimental rats performing in a motor-driven activity wheel shows a limited region of high metabolic activity, as revealed by the deoxyglucose radioautographic method. This region consists of a bilateral band located in the somesthetic area SI. An overlap of this labeling with the sensory and/or motor cortical representation of the head, and especially a correlation with head posture and movements, is discussed.

Animals↗
PubMed1982

[Spatial discrimination with thermal reinforcement in the young rat. (author's transl)].

Infant rats, because of their deficient thermoregulation, are very reactive to thermal stimuli. In our experiences, four to ten day old animals were trained a discriminative locomotor response between two places of a symmetrical device. A correct choice was reinforced by a 30-35 degree air stream during twenty seconds. One hundred and forty Wistar rats (male and female) were submitted to a twenty trial acquisition session (intertrial interval = 20 seconds). Those who reached a 70% correct criterion were trained to reverse their initial discrimination. Spontaneous alternation and "vicarious trial and errors" (VTE) were systematically observed. Percentages of correct responses in the two tests increased with age and reached a maximum in nine and ten day old rats. This increase was mainly due to a decrease of percentages of incorrect responses. Spontaneous alternation rate also progressed with age but did not reach adult level. VTE appeared in nine day old rats and were highly positively correlated with correct responses.

Aging↗
PubMed1982

[Operant conditioning with thermal reinforcement in the newborn rat].

In previous experiments, we studied the acquisition of instrumental locomotor responses reinforced by thermal stimuli, in one to ten-day-old rats. In these tasks, there was a precise topographic relation between the behavior to be conditioned and the reinforcement. In the experiment reported in the present paper, one to eight-day-old rats were tested in an operant conditioning task, where the operant (OP) was a non locomotor behavior, the raising of the head. At each day of age, two paired groups were compared: a "contingent" (C) and a "non contingent" (NC) group. Each OP (satisfying an amplitude criterion) of a C rat was reinforced by the application of a 30-35 degrees C air-stream during ten seconds. The NC rat of the same pair received the same number of air-streams during the session, but these stimuli were unrelated to its behavior. The duration of the session was ten minutes. Mean frequency of OP was higher in C than in NC groups, at one, two, six, seven and eight day of age. Absence of significant differences between C and NC groups at three, four and five days of age could be due to the competition between OP and the emerging locomotor behavior.

Animals↗
PubMed1982

Associative and non-associative changes in unit activity of the rat hippocampus.

Two main types of neurons of the dorsal hippocampus were recorded in chronic rats during the classical conditioning of an arousal phenomenon (neocortical EEG desynchrony). The relative importance of the associative and non-associative factors was assessed by a differentiation procedure. In naive rats, during the "acquisition" session most type-I neurons rapidly acquired an "inhibitory" response closely parallel to the EEG response. Neither of these responses showed differentiation. Some type-II neurons acquired an "excitatory" response which was independent of the EEG response and which had a significant tendency to differentiation. These data were confirmed in rats submitted to several "retention" sessions. All the type-I neurons were undifferentiated while 11 out of 41 type-II neurons were differentiated. Type-I neurons were characterized by a bursting mode of discharge. Their activity was higher during slow wave sleep (SWS) than during wakefulness (W) or paradoxical mode of discharge. Most of the differentiated type-II neurons were more active during W and/or PS than during SWS.

Acoustic Stimulation↗
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↗