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Biomedical subjects

B Cardo

Publications and source records attributed to B Cardo.

15 recordsLinked to original sources
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↗
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↗
PubMed1975

[Rhythmic slow waves and multi-unit activity during sleep-waking cycle in the rat ventral tegmentum].

1. Multi-unit activity (MUA) was recorded together with gross activity in different structures during various states of sleep in 43 rats. The records were made by means of telemetry from lateral hypothalamus, nucleus ruber, formatio reticularis, dorsal hippocampus and the ventral mesencephalic tegmentum (VMT) surrounding the nucleus interpeduncularis. 2. The records during paradoxical sleep showed slow rhythmic theta waves located in the VMT and the dorsal hippocampus. In these two structures the MUA was mainly organized in periodic patterns of discharges. In the other structures a continuous increment of the basic level of discharge was superimposed on the periodic patterns. 3. The similarity of the hippocampal and VMT records strengthens the hypothesis that the VMT region has anatomical and functional connections with the limbic system.

Action Potentials↗
PubMed1975

Rhythmic slow wave activity recorded in the ventral mesencephalic tegmentum in the rat.

1. Slow rhythmic theata-type waves were recorded in the sub-interpeduncular ventral mesencephalic tegmentum (VMT) in the rat. This region is one of the parts of the "limbic midbrain area". These waves are recorded during certain attentive waking states, during the execution of voluntary movements and during paradoxical sleep. 2. These rhythmic VMT waves seem to be of the same nature as the theta rhythm recorded in the limbic structures. A lesion of the septum suppresses the slow rhythmic waves at the mesencephalic level as well as at the telencephalic level. 3. Although we have now shown that the mesencephalic and telencephalic slow rhythmic waves have the same pacemaker, the pathways which transmit the theta rhythm to the VMT are not well known. However, it is reasonable to suppose that the fibres of the post-commissural fornix are involved in this transmission.

Animals↗