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D Galey

Publications and source records attributed to D Galey.

30 records · Page 2Linked to original sources
PubMed1983

Facilitation of memory consolidation by post-training electrical stimulation of the medial septal nucleus: is it mediated by changes in rhythmic slow activity?

Sinusoidal (100 Hz) electrical stimulation was applied at a weak intensity (7.5 muA peak to peak) through bipolar electrodes located in the medial septal nucleus after partial acquisition of an appetitive operant conditioning task in a Skinner box. Analysis of performance in a retention test 24 hr later showed that (i) the presence of stimulation electrodes by itself impaired retention-test performance, and (ii) electrical stimulation applied 30 sec after the end of the acquisition session improves retention; this facilitatory effect disappeared when the treatment was delayed 15 min. Both impairment and facilitation were found to vary (considerably) among subjects. Electrodes located in the center of the medial septal nucleus led to both a greater impairment in unstimulated subjects and a greater facilitation in stimulated subjects than more anterior placements in the vicinity of the diagonal band. Finally, spectral analysis of hippocampal EEG showed that stimulation had no effect on rhythmic slow activity (RSA). These results are discussed in relation to studies showing that RSA is associated with memory-storage processes and our own hypothesis which underlines the importance of activation of septo-hippocampal cholinergic neurons in the early stages of these mnemonic processes.

Animals↗
PubMed1982

[Facilitation of memory consolidation induced by electrical stimulation of the medial septal nucleus in BALB/c mice (author's transl)].

Sinusoidal (100Hz) electrical stimulation was applied at a weak intensity (7.5microA peak to peak) to the medial septal nucleus after partial acquisition of an appetitive operant conditioning task in a Skinner box. Analysis of performance recorded 24 hrs later during a retention session shows that (i) implantation alone impaired performance; (ii) electrical stimulation applied 30 sec. after the end of the acquisition session improves retention; this facilitatory effect disappears when the treatment is delayed 15 min. Furthermore spectral analysis of hippocampal EEG showed that there was no significant modification of theta rhythms. These results are discussed in relation to studies in the literature which demonstrate that RSA (rhythmical slow activity) is associated with memory-storage processes and our own hypothesis which underlines the importance of activation of septo-hippocampal cholinergic neurons in the early stages of these mnemonic processes.U

Animals↗
PubMed1977

Behavioral effects of lesions in the A10 dopaminergic area of the rat.

Experiments have been carried out with 150 rats in order to study some psychophysiological functions of the mesencephalocortico limbic dopaminergic A10 group. Lesions in the A10 area were made by using 6-hydroxydopamine (6-OHDA) local injections; 2 small volumes of injections were used at the same concentration (2 mug/1 mul or 1 mug/0.5 mul). In a first experiment the effects of these two injections were tested on locomotor activity measured in a circular corridor, 10 and 30 days after surgery. Injections provoked hyperactivity, mainly during nocturnal basal activity periods, but not during initial exploratory activity periods. The larger the injection, the more important the hyperactivity was. The larger injections induced important food spillage evidence through the wire floor of the home cage and perturbation in a passive avoidance learning. There was no change in body weight or in amount of ingested food. In a second experiment, the effects of local injection of 6-OHDA in the other CA structures or bundles situated in or near the ventral tegmental area were tested. Injections in the substantia nigra compacta, in the noradrenergic ventral bundle, in the dorsal periventricular system-tegmental radiations did not provoke locomotor hyperactivity. In a third experiment, a possible role of the median raphe (MR) nucleus in the A10-lesion induced hyperactivity was tested: first, radiofrequency MR lesions were made and no durable significant hyperactivity was recorded; secondly, 6-OHDA (1 mug/0.5 mul) was injected into the A10 area and activity was measured 10 days later: these injections provoked significant hyperactivity during the nocturnal basal and the diurnal basal activity periods. It might be concluded that neither the neighboring CA fibers nor the MR were directly involved in the ventral tegmental -- 6-OHDA lesions syndrome. Anatomical controls by using the Fink-Heimer silver impregnating method have demonstrated, first, that the 6-OHDA injections did not destroy fibers other than catecholaminergic and secondly, that the degenerations are found in the forebrain and cortical limbic A10 projections. Hypotheses are made about a possible general inhibitory role of the A10 in behavior, in the sence of selective and attentive arousal processes, often impaired in some mental illnesses.

Animals↗
PubMed1977

[Respective effects on locomotor activity of injections of 5, 7-DHT in median raphe nucleus and of 6-OHDA in the mesolimbic dopaminergic group area in the rat].

This experiment was performed in order to demonstrate that the locomotor hyperactivity provoked by a radiofrequency lesion of the ventral mesencephalic tegmentum-A10 DA group area was not due to a 5-HT fiber damage. Four groups of Rats were used. First groups II and IV received a 5, 7-DHT injection in the median raphe; groups I and III received the vehicle. Locomotor activity was measured in a circular corridor 10 and 30 days; no hyperactivity was obtained. Then the same groups received a 6-OHDA injection, bilaterally in the A 10 area (groups III and IV) or the vehicle (groups I and II); the activity was measured 10 days later: significant hyperactivity was obtained with groups III and IV, without statistical differences between these two groups. In conclusion (i) 5-HT neurons are not directly involved in the VMT-hyperactivity, (ii) the DA A 10 neurons seem to be a critical anatomical target for this symptom.

Animals↗
PubMed1976

Silver impregnation of dopaminergic systems after radiofrequency and 6-OHDA lesions of the rat ventral.

Nauta and Fink-Heimer silver impregnation techniques were used to study the anterior degeneration produced by radiofrequency (RF) or 6-OHDA lesions in the medial and lateral ventral mesencephalic tegmentum (VMT), substantia nigra and dorsalis tegmental decussation (DTD) in rats. Both Nauta and Fine-Heimer impregnating methods showed that RF lesion of the VNT produced degeneration in three major pathways: a ventral pathway corresponding to the fasciculus medialis prosencephali (FMP), an intermediate pathway projecting to the ventral thalamus, and a dorsal pathway to the medio-dorsal thalamus and to the nucleus lateralis habenulae. In addition, the Fink-Heimer method demonstrated prejections of the dopaminergic A10 and A9 cell group in the VMT to the nucleus caudatus after RF or 6-OHDA lesions. Projections to nucleus accumbens, tuberculum olfactorium, stria terminalis, and cortex frontalis were observed only after 6-OHDA lesion of the A10 cell group. Degeneration in cortex cinguli and entorhinalis was seen mainly after 6-OHDA lesion of the A9 cell group. The limbic forebrain cortical projections of the A10 group provide a coherent anatomical basis for the behavioral syndrome provoked by RF and 6-OHDA lesions in the VMT.

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