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Biomedical subjects

A R Cools

Publications and source records attributed to A R Cools.

At least 217 records · Page 12Linked to original sources
PubMed1982

Evidence for a role of the caudate nucleus in the sequential organization of behavior.

Behavioural effects of the cholinergics carbachol and atropine given by means of telestimulation were studied in small groups of freely moving Java monkeys. The sequential structure of behavior was analyzed by assessing the contribution of the preceding behaviours of the treated monkey and its partners to the subsequent behaviour of the treated monkey, in terms of information-theoretical statistics. Carbachol increased the overall variability of behaviour in the treated monkey, enhanced the dependency between the preceding and subsequent behaviour of the treated monkey, and slightly decreased the dependency between the current behaviour of the treated monkey and the preceding behavior of its partners. Atropine only increased the dependency between the treated monkey's current behaviour and the preceding behaviour of its partners. The morphology of overt behaviour remained unaffected following the chosen treatments. Analysis of changes in the frequencies of behaviours belonging to different motivational categories (maintenance, sex, aggression, submission and affiliation) revealed that, after intracaudate injections, all categories were affected to the same degree; in contrast, amygdala injections only affected the categories 'aggression' and 'submission'. It is concluded that the caudate nucleus establishes the relative priority of intra-individual and inter-individual constraints on the programming of behaviour, thereby providing flexibility in the execution of ongoing behaviour; the caudate nucleus is not primarily involved in motor control, nor in the control of particular categories of behaviour.

Amygdala↗
PubMed1981

Presence of a particular subpopulation of dopamine receptors within the septal nuclei: a behavioural study on cats.

The behavioural effects of intraseptal administration of dopaminergic drugs (apomorphine, haloperidol, (3,4-dihydroxy-phenylamino)-2-imidazoline (DPI), ergometrine and dopamine) and alpha-noradrenergic drugs (oxymetazoline, noradrenaline and phentolamine) were analysed in cats pretreated with morphine (5 mg/kg, i.p.). Changes in frequencies of stereotyped locomotor patterns were used for statistical evaluation of drug-induced effects. Taking advantage of the specificity of the drugs mentioned, a distinction could be made between effects mediated via excitation-mediating dopamine (DAe), inhibition-mediating dopamine (DAi) and alpha-noradrenaline (alpha-NA) receptors. Intraseptal injection of the DAi agonist DPI resulted in a decrease in the frequency of stereotyped locomotor patterns. This effect was dose-dependent and mimicked by that of intraseptally applied dopamine but not of any of the other drugs. Moreover, intraseptal injection of the DAi antagonist ergometrine inhibited the effect of DPI. The DAe agonist apomorphine as well as the DAe antagonist haloperidol remained ineffective when applied in low doses. The alpha-NA antagonist phentolamine and a rather high dose of haloperidol produced a slight but significant increase in the frequency of locomotor patterns; intraseptally applied oxymetazoline counteracted the phentolamine-induced effect. It is concluded that the septal nuclei of cats contain functionally active, alpha-NA receptors as well as functionally active, dopamine (DA) receptors having pharmacological properties identical to those of DA receptors present within the mesolimbic structures such as the nucleus accumbens: the so-called inhibition-mediating DAi receptors.

Animals↗
PubMed1980

Role of the neostriatal dopaminergic activity in sequencing and selecting behavioural strategies: facilitation of processes involved in selecting the best strategy in a stressful situation.

The purpose of this study was to detect the behavioural effect of drug-induced changes in the neostriatal dopaminergic activity upon the degree of intrinsic (self-generated) and extrinsic (externally produced) constraints on the selection of behavioural patterns in rats. Both systemic and neostriatal injections of extremely low doses of apomorphine and haloperidol were used to change the neostriatal dopaminergic activity. Behavioural changes were observed in (a) an open-field test, (b) a so-called 'swimming without escape' test, (c) a so-called 'swimming with escape' test, and (d) a test to detect deficiencies in sensory, motor and sensorimotor capacities required to perform both swimming tests. Evidence is found that the neostriatum, especially the neostriatal, dopaminergic activity determines the animal's ability to select the best strategy in a stressful situation by modifying the process of switching strategies under pressure of factors intrinsic to the organism: neither sensory neglect nor inability to initiate voluntary movements underlay the observed phenomena. It is suggested that the neostriatum determines the individual flexibility to cope with available sensory information.

Animals↗
PubMed1978

Distinct dopaminergic systems in ACTH-induced grooming.

Excessive grooming behavior induced in rats by intraventricular injection of ACTH1-24 was inhibited by selective pharmacological manipulation of two functionally distinct types of dopaminergic terminals (DAe and DAi) in the neostriatum or the nucleus accumbens. It is concluded that when ACTH1-24 produces the behavioral response it modulates the activity of both the DAe and the DAi systems.

Adrenocorticotropic Hormone↗
PubMed1978

Atonia after carbachol microinjections near the locus coeruleus in cats.

The effect of microinjections of carbachol into the dorsolateral pontine tegmentum on the behaviour of cats is investigated. Injections of small amounts (50 and 500ng) of carbachol into the pontine reticular formation induced muscular atonia in otherwise awake animals. The atonia is not due to cholinergic stimulation of the noradrenergic cells of the locus coeruleus or the dorsolateral pons, since the most effective sites were situated ventrally to the locus coeruleus and alpha- and beta-adrenergic blocking agents did not affect the antonia. The results are discussed in view of the postulated role of the locus coeruleus in paradoxical sleep.

Animals↗
PubMed1978

Ergometrine and its biphasic action at dopaminergic receptors in the nucleus accumbens of rats.

Bilateral administration of ergometrine into the nucleus accumbens of rats pretreated 40 min earlier with apomorphine (0.9 mg/kg, s.c.) resulted in a shift from a predominant licking score to a predominant gnawing score. Bilateral administration of ergometrine or (3.4-dihydroxyphenylamino)-2-imidazoline into the brain of rats treated 20 min later with apomorphine (2.0 mg/kg, s.c.) resulted in a shift from a predominant licking and gnawing score to a predominant walking and sniffing score. These and related data suggest a biphasic action at a certain group of dopamine receptors within the nucleus accumbens of rats: a short-term activation and along-term inhibition following this initial activation. The predictive value of the behavioural profile triggered by ergometrine for the evaluation of antidepressant effects of centrally acting drugs is discussed.

Animals↗