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B Cardo

Publications and source records attributed to B Cardo.

At least 37 records · Page 2Linked to original sources
PubMed1977

Effects of apomorphine on self-stimulation behaviour in dorsal and ventral area of lateral hypothalamus in mice.

Intraperitoneal injections of low doses of apomorphine, a dopaminergic receptor agonist, depressed briefly, and then enhanced self-stimulation behaviour in the dorsal area of lateral hypothalamus. In contrast, only depressant effects were observed in the ventral area. These differential effects suggest the presence of a dopaminergic componant in the dorsal hypothalamic self-stimulation system.

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.

Animals↗
PubMed1976

[Changes in cholinergic mechanisms and in learning in three strains of inbred mice after electric stimulation of the dorsal hippocampus].

Two experiments investigated the neurochemical correlates of hippocampal stimulation effects on learning in three inbred strains of Mice. In the 1st experiment, it was shown that subseizure electrical stimulation of the dorsal hippocampus, 30 sec. after a partial appetitive learning session (1) improved 24 hrs. delayed performances of BALB/c Mice (2) had little but significant effect on C57BL/6 (3) had no effect on C57BR animals. The second experiment was aimed at studying the stimulation effect on hippocampal cholinergic mechanisms by testing the two main enzymes involved in acetylcholine synthesis and degradation (choline acetyltransferase = ChAc and acetylcholinesterase = AChE). The major findings of this experiment were as follows: (1) stimulation induced a 3 hrs. delayed improvement of ChAc activity for the BALB/c strain (2) a similar but less important effect was observed in C57BL/6 Mice (3) there was no effect for C57BR animals. These result further support the view that cholinergic hippocampal mechanisms act upon memory consolidation.

Acetylcholinesterase↗
PubMed1976

[Late consequences of an early stimulation of the lateral hypothalamus on the acquisition and extinction of alimentary conditioning].

Male Sprague Dawley rats received at 13 days of age bilaterally implanted electrodes in lateral hypothalamus. At 15th and 16th days of age they underwent a total of 4 hrs imposed stimulation, according to a self-stimulation model of a 15 days animal. Electrodes were removed on the 17th day. Between the 42nd and 46th days, animals were tested in a skinnerian, alimentary reinforced task. In acquisition as well as in extinction behavior, early stimulated animals performed better than animals of the same age, implanted but non stimulated or non implanted.

Animals↗
PubMed1976

Effects of various inhibitors of tyrosine hydroxylase and dopamine beta-hydroxylase on rat self-stimulation after reserpine treatment.

The behavioral effects of low doses of the catecholamine (CA) synthesis inhibitor, alpha-methyl-p-tyrosine (alpha-MPT, 50 mg/kg i.p.), or the norepinephrine (NE) synthesis inhibitors (FLA-63, 15 mg/kg i.p., U-14624, 50 mg/kg i.p., or disulfiram 150 mg/kg i.p.) were studied in rats pretreated with reserpine (1 mg/kg i.p.) 24 h before. Rats were implanted either in the area ventralis tegmenti (AVT) or in the lateral hypothalamus (LH). The modifications of CA synthesis and endogenous CA levels were estimated in a parallel experiment. Reserpine treatment produced a slow decrease in self-stimulation (SS) rates during the first 12 h; SS rates were 85% of control values 24 h after reserpine treatment. Injection of alpha-MPT in reserpine-pretreated rats inhibited SS (85% decrease 3 h after administration either in AVT or LH rats), whereas dopamine beta-hydroxylase inhibition had no great effect on SS. The administration of very low doses of alpha-MPT (20 mg/kg i.p.) to rats treated with reserpine (24 h before) plus FLA-63 (1 h before) induced an important decrease in SS rates in AVT-implanted rats only. The major conclusion is that dopaminergic neurons seem to be involved in AVT and LH SS. The last experiment suggests the involvement of a balance between dopaminergic and noradrenergic neurons in AVT SS.

Animals↗
PubMed1976

[Passive avoidance in two inbred strains of mice: conditioned emotional response and specific avoidance].

Specific response inhibition and generalized behavioral suppression (conditioned emotional response) contributions to a step-through passive avoidance performance are tested in two inbred strains of mice. For this purpose response contingent (0 sec.) and delayed punishment (from 5 to 60 sec.) are used in the learning session. The results of the test session (24 hr later) show that in the BALB/c strain, the response contingent component is very important (i.e. delaying the punishment produces a rapid decrease of the step-through latency). On the otherhand the latency remains unaffected in C57 BL/6 mice, showing that conditioned emotional response is the major determinant of the passive avoidance performance in this strain. These results might at least partially explain some contradictory results about memory differences between inbred strains of mice. Moreover they show that more sophisticated behavioral analysis is necessary whenever interstrain comparisons or genetic analysis are used for studying learning and memory.

Animals↗
PubMed1976

The role of hippocampal cholinergic mechanisms in the aquisition of a barpress response.

The role of hippocampal cholinergic mechanisms in learning a bar-press response reinforced with food was investigated. Firstly, an interstrain comparison showed that mice having a low choline acetyltransferase activity in the dorsal hippocampus were quicker to associate the barpress with reinforcement. Secondly, when the activity of this enzyme was reduced by a subseizure electrical stimulation of the hippocampus learning was accelerated. It is suggested that acetylcholine availability at the hippocampal synapses slowed the apparition of these learned responses.

Acetylcholinesterase↗
PubMed1975

[Improvement of memory by post-experiment BALB/c mouse lateral hypothalamus stimulation].

In order to test the influence of a post-trial low level rewarding stimulation on learning, BALB/c mice were bilaterally implanted in the lateral hypothalamus. First, all the animals were submitted to a 15 mn appetitive learning session in a Skinner Box (CRF). 30 s later, animals of the experimental group were stimulated for 80 s (100 Hz sinusoidal current; 200 ms ON/200 ms OFF; 10 muA/electrode). 24 h later the performances of the stimulated animals were compared to those of non-stimulated or not implanted animals. An improvement of reminiscence effect was observed in stimulated animals. Second, the self-stimulation behavior was studied in stimulated subjects; at 10 muA, this behavior was effective in all animals. The results are interpreted as revealing the involvement of the rewarding system in memory processes.

Animals↗
PubMed1975

[Distrubance in retention of a conditioned feeding behavior in mice by subconvulsant electrical stimulation of the cerebral cortex].

A bilateral 80 s stimulation of the parieto-occipital cortex was applied 200 s after a former partial acquisition test in a Skinner box. It has resulted in an impairment of the performances obtained 24 h later through a second test. This effect was greater the greater the stimulus, this latter being always kept under threshold values of post-discharges. These results seem to reveal that reminiscence phenomena are under the control of neocortex, in a somewhat discrete way which does not produce any retrograde amnesia.

Amnesia, Retrograde↗