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PubMedDate not supplied

[Learning in rats with differing emotional responsiveness and its relation to brain monoamines].

The ability for learning was studied in two groups of Wistar line rats divided by susceptibility to the audiogenic stress-stimulation as compared with the monoamines level in various brain structures. The best ability to learn avoidance reaction in a shuttlebox was shown by animals non-resistant to the stress stimulus as compared with the resistant rats, which correlated positively with the exploratory activity in "the open field". The distinct feature of the animals non-resistant to the stress stimulation consisted in a higher reactivity of the monoamine systems, mainly of the noradrenergic system. This group of animals was also characterized by a higher dopamine content and a lower noradrenaline content in the brain-stem. Decreased activity of the brain dopamine-beta-hydroxylase in animals non-resistant to the stress stimulus, has been suggested.

Animals↗

PubMed1992

The effects of receptor blockers on brain natriuretic peptide-32-induced action on passive avoidance behavior in rats.

The effects of several doses of porcine brain natriuretic peptide-32 (pBNP-32) administered into the lateral brain ventricle were tested as regards the consolidation of passive avoidance learning in rats. The peptide was found to increase the passive avoidance latency in a dose-dependent manner. In order to clarify which transmitter systems might be involved in the action of pBNP-32, the experimental animals were pretreated with different receptor blockers in selected doses which did not influence the behavioral paradigm. Four of the receptor blockers (haloperidol, atropine, phenoxybenzamine and propranolol) effectively blocked the action of the peptide on the consolidation of passive avoidance learning. The other three (naloxone, bicuculline and methysergide) were ineffective. The results suggest that dopaminergic, cholinergic and alpha- and beta-adrenergic mediations might be involved in the effects of pBNP-32 on the consolidation of passive avoidance learning in rats.

Animals↗

PubMed2006

Treadmill running reverses retention deficit induced by morphine.

Human and animal studies have suggested that exercise has benefits overall health and cognitive function. The aim of this study was to investigate the effect of treadmill running on passive avoidance learning and memory deficit in morphine-treated rats. The passive avoidance learning was measured in different time intervals (1, 2 and 24 h as well as 1 week and 1 month). Four groups of rats were included as follows: control, morphine-treated, exercised-saline and exercised-morphine-treated group. The electrical foot shock and treadmill training (2 h at a speed of 5 m/min for 10 days) were applied for all the groups. The data obtained was analyzed using unpaired Students t-test and ANOVA test with group as the independent variable, and performance in each session (avoidances and crossings) as the dependent variables. The results show that the total time staying in dark box was decreased in exercised-saline and exercised-morphine-treated rats by treadmill running (P<0.05). The avoidance learning was significantly reduced in morphine-treated group as indicated by the increased total time of staying in the dark box compared with the control group (P<0.05). We could conclude that exercise increased the delay time of entry to the dark electrical foot shock box, suggesting that morphine impaired the short-term memory and learning and this was reversed by the treadmill running.

Analgesics, Opioid↗

PubMed2001

The relationship of work avoidance and learning goals to perceived competence, externality and meaning.

BACKGROUND: Motivational researchers have suggested that work avoidance may be an academic goal in which students seek to minimise the amount of work they do in school. Additionally, research has also suggested that emotions may be catalysts for goals. AIM: This study examined the relationship between emotions and learning or work avoidance goals. Do emotions explain goals? SAMPLE: The participants were 512 senior high school students in Eastern Canada. METHOD: Students completed a survey assessing motivation related constructs. A structural equation model was postulated in which students' affect predicted learning goals and work avoidant goals. A cluster analysis of affect scores was performed followed by between-group and within-group contrasts of goal scores. RESULTS: The structural equation model suggested that a sense of competence and control were predictive of a learning goal while lack of meaning was related to work avoidance. The cluster analysis showed that confidence and control were associated with a learning goal but that a sense of inadequacy, lack of control or lack of meaning could give rise to work avoidance. CONCLUSIONS: Emotions seem to be directly linked to goals. Teachers who foster feelings of self-assuredness will be helping students develop learning goals. Students who feel less competent, bored or have little control will adopt work avoidant goals.

Adolescent↗

PubMed1994

Leg position learning in the cockroach nerve cord using an analog technique.

The ultimate goal of this research is to correlate neural activity with leg behavior during learning. Contrary to previous studies of shock avoidance learning in the headless cockroach, in which an all-or-none method of recording was used, we have adopted a direct analog recording of leg position to measure learning in the prothoracic ganglion. This method provides a sensitive and continuous record of leg movement that can be correlated with the interactions of individual neurons that may be involved in such learning. Of the 10 prothoracic legs trained to flex to avoid shock, eight escaped shock by flexion within a maximum of 13 min and seven showed savings when retested. Only four of eight prothoracic legs trained to extend showed avoidance learning and all four showed savings. Electrical stimulation of nerves 3,4,5, and 6 innervating the prothoracic leg revealed which nerves were instrumental in the flexion and extension responses.

Animals↗

PubMed2001

Nitric oxide modulates lithium-induced conditioned taste aversion.

Nitric oxide (NO) has been shown to affect the behaviour in animal models of depression, anxiety and avoidance learning. Lithium has marked effect in avoidance learning, an effect that can be modulated via the 5-HT system. Experiments were carried out using the conditioned taste aversion (CTA) paradigm to investigate whether administration of NO-modifying drugs, serotonergic drugs and lithium, alone or in combination, induced or affected a CTA. The NO-precursor L-arginine (L-Arg), the non-specific inhibitor of NOS and guanylate cyclase, methylene blue (MB) and the specific NOS inhibitor 7-Nitroindazole (7-NI) all produced CTAs in a dose-dependent fashion. Furthermore, we found that L-Arg counteracted the CTAs induced by LiCl or MB but failed to modulate the CTA produced by 7-NI. The administration of the selective 5-HT1A agonist, 8-OH-DPAT, counteracted the CTAs produced by MB and 7-NI. In contrast, depletion of 5-HT by p-Chlorophenylalanine did not affect the aversions produced by MB and 7-NI, but counteracted the CTA produced by L-Arg. Our results suggest that NO plays a role in the acquisition of the CTA induced by LiCl. Furthermore, the results suggest that the 5-HT1A receptor plays an important role in the CTA induced by MB and 7-NI, thus indicating a possible interaction between the 5-HT and NO systems.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1983

Two-way avoidance and acute shock stress induced alterations of regional noradrenergic, dopaminergic and serotonergic activity in Roman high- and low-avoidance rats.

Various brain regions of male RHA/Verh and RLA/Verh rats were dissected out and deep-frozen immediately after 30 min in a shuttle box involving a) no shock (control), b) 40 inescapable shocks or c) 40 avoidable shocks. The RHA/Verh rats used in the "c" category exhibited about 80-85% learned avoidance. 5-HT, 5-HIAA, NA, MHPG-SO4, DA, DOPAC and HVA levels were subsequently measured in selected regions. NA levels were considerably reduced in the hypothalamus and pons/medulla of both selected lines of rats after acute shock stress, supporting the results of numerous studies which have indicated that NA turnover is nonspecifically increased by all types of stress, at least in those regions. An increase in cortical MHPG-SO4 and a reduction in hypothalamic 5-HT seen after avoidance learning also occurred after shock stress in RHA/Verh rats. Whereas RLA/Verh rats showed an increased metabolism of 5-HT in the hypothalamus and pons/medulla after shock stress, RHA/Verh rats showed the opposite response in the hypothalamus after the same treatment. A reduction in 5-HT metabolism was also evident in RHA/Verh rats, after avoidance learning, in the cortex, hippocampus and hypothalamus. These results indicated, pending further studies regarding, for example, possible genetic differences in tryptophan uptake and utilization, that 5-HT probably plays at least a modulatory role in the reaction to stress, and in avoidance behavior. That role may be either active or passive, depending upon the emotional status of the subjects. In regard to the DA responses measured in striatum and hypothalamus of the two rat lines, some divergent inter-treatment tendencies, as well as some similarities, were seen in DA metabolism in both regions, but almost none of the differences were significant.

Animals↗

PubMed1997

Stimulation of delta1- and delta2-opioid receptors produces amnesia in mice.

The effects of intracerebroventricular administration of delta1- and delta2-selective opioid receptor agonists on spontaneous alternation performance, elevated plus-maze behavior and passive avoidance learning including step-down and step-through types were examined in mice. Although the delta1-selective opioid receptor agonist, [D-Pen2,L-Pen5]enkephalin (DPLPE) (1-10 microg) or the delta2-selective opioid receptor agonist, [D-Ala2]deltorphin II (deltorphin) (1-10 microg) did not markedly affect spontaneous alternation performance or elevated plus-maze behavior, DPLPE (1, 3 and/or 10 microg) and deltorphin (3 and 10 microg) inhibited passive avoidance learning including step-down and step-through types. The delta1-selective opioid receptor antagonist, 7-benzylidenenaltrexone (3.5 ng), and the delta2-selective opioid receptor antagonist, naltriben (19 ng), significantly antagonized the inhibitory effects of DPLPE (3 microg) and deltorphin (3 microg) on passive avoidance learning, respectively. In contrast, DPLPE (3 microg) or deltorphin (3 microg) did not markedly influence behavioral responses induced by electroshocks during training of passive avoidance learning. Moreover, DPLPE (0.3-3 microg) or deltorphin (0.3-3 microg) failed to significantly affect the radiant heat-induced nociceptive responses. These results suggest that stimulation of delta1- and delta2-opioid receptors produces amnesia, depending on the learning tasks used.

Amnesia↗

PubMed1976

Differential effects of unilateral and bilateral caudate lesions on side preference and passive avoidance behavior in rats.

The effects of unilateral and bilateral caudate lesions on side preferences, passive avoidance learning and locomotor activity were determined in rats. Unilateral lesions ipsilateral to preoperative side preferences increased side preference and facilitated passive avoidance learning. Contralateral lesions reversed side preferences and impaired passive avoidance learning. Bilateral lesions increased side preference in some rats and decreased or reversed side preference in other rats; the increase or decrease in side preference was related to a lesser or greater impairment in learning, respectively. All caudate lesions increased locomotor activity. It is suggested that an intrinsic nigro-striatal asymmetry has a modulatory role in learning and that the effects of bilateral caudate lesions are, in part, attributable to very slight asymmetries in lesion locations. The effect of a unilateral caudate lesion will depend upon whether the lesion is placed in the more or less active striatum.

Animals↗

PubMed2006

Beneficial effects of docosahexaenoic acid on active avoidance performance in 1K-1C hypertensive rats.

The present study evaluated the role of chronic docosahexaenoic acid (DHA) supplementation on active avoidance learning task performance in experimental hypertension. Male Wistar rats were randomly divided into five experimental groups as follows: control, sham, DHA treated, 1K-1C hypertensive, and 1K-1C hypertensive+DHA treated. Hypertension was induced in 1K-1C rats via placing a silver clip (0.20-mm ID) around the left renal artery following a right uninephrectomy. DHA (36 mg/kg/day) was given to the treatment groups for 60 days by gastric gavage. Arterial blood pressure was measured by using the tail-cuff method. Active avoidance responses were determined by an automated shuttle-box. In brain (cerebrum) and hippocampus tissues, thiobarbituric acid reactive substances (TBARS) and nitrite levels were measured by fluorometric methods. DHA supplementation decreased blood pressure in hypertensive rats. Data from active avoidance training indicated that performance of active avoidance learning tasks were significantly impaired in 1K-1C hypertensive rats, but was completely restored by DHA supplementation. Increased cerebrum TBARS levels in 1K-1C rats were abolished by DHA administration. Cerebrum nitrite levels were lower in the DHA, 1K-1C and 1K-1C+DHA treated groups compared to controls. Hippocampus nitrite levels were lower in DHA treated and 1K-1C hypertensive rats compared to controls and higher in 1K-1C+DHA treated rats compared to the 1K-1C group. Our data indicates that DHA supplementation improves the performance of active avoidance learning tasks which is impaired in experimental hypertension. These affirmative changes might be due to a DHA-induced decrease in lipid peroxidation which may in turn limit the consumption of nitric oxide (NO) which promotes active avoidance learning.

Animals↗

PubMed1990

Influence of kynurenine treatment on open-field activity, elevated plus-maze, avoidance behaviors and seizures in rats.

In the present studies the effects of single and daily repeated injections of kynurenine were investigated in different behavioral tests in rats. In open-field behavior a single injection of kynurenine decreased rearing activity, while the effect was more pronounced after repeated injections. Similarly, in the elevated plus-maze, kynurenine attenuated the total number of entries in the four arms of the equipment, and after chronic treatment decreased the time spent in the open arms (control: 24%; kynurenine 100 mg/kg: 16%; kynurenine 200 mg/kg: 13%). Kynurenine did not influence the passive avoidance learning paradigm (learning session and avoidance latency) and the extinction of active avoidance response. Kynurenine slightly attenuated the kainic acid-induced wet dog shakes and forelimb clonic activity with rearing. These findings suggest that kynurenine (especially after repeated peripheral injections) inhibited several behavioral responses of the experimental animals. However, in one type of highly motivated experimental paradigm (fear from the foot shock), behavioral depression was not detectable.

Animals↗

PubMed1982

Developmental and behavioral effects of maternal alcohol exposure in rats.

Fostered rat offspring whose mothers had been administered 7.5% alcohol solution (4.85 g/kg/day) as drinking fluid during 0-17 days of gestation were compared with equivalent groups whose dams had given ad libitum and restricted volume of tap water in the following behavioral tests: reflex test, swimming behavior test, open-field test, radial-maze learning and two-way avoidance learning. The treatment with alcohol resulted in developmental delay in ear-flaps uncurling, placing reflex, swimming behavior, walking in addition to reduction in body weight at 1 and 7 days of age. The treated group also exhibited decreased open-field activity and deficit in the avoidance learning. The results show that maternal alcohol consumption produces developmental and behavioral deficits in offspring, which are comparable to the fetal alcohol syndrome (FAS) in man.

Animals↗

PubMed2004

Glutamatergic activation of anterior cingulate cortex produces an aversive teaching signal.

Noxious stimuli have motivational power and can support associative learning, but the neural circuitry mediating such avoidance learning is poorly understood. The anterior cingulate cortex (ACC) is implicated in the affective response to noxious stimuli and the motivational properties of conditioned stimuli that predict noxious stimulation. Using conditioned place aversion (CPA) in rats, we found that excitatory amino acid microinjection into the ACC during conditioning produces avoidance learning in the absence of a peripheral noxious stimulus. Furthermore, microinjection of an excitatory amino acid antagonist into the ACC during conditioning blocked learning elicited by a noxious stimulus. ACC lesions made after conditioning did not impair expression of CPA. Thus, ACC neuronal activity is necessary and sufficient for noxious stimuli to produce an aversive teaching signal. Our results support the idea that a shared ACC pathway mediates both pain-induced negative affect and a nociceptor-driven aversive teaching signal.

Animals↗

PubMed2005

Altered dendritic arborization of amygdala neurons in young adult rats orally intubated with Clitorea ternatea aqueous root extract.

Young adult (60 day old) Wistar rats of either sex were orally intubated with 50 mg/kg body weight and 100 mg/kg body weight of aqueous root extract of Clitoria ternatea (CTR) for 30 days, along with age-matched saline controls. These rats were then subjected to passive avoidance tests and the results from these studies showed a significant increase in passive avoidance learning and retention. Subsequent to the passive avoidance tests, these rats were killed by decapitation. The amygdala was processed for Golgi staining and the stained neurons were traced using a camera lucida and analysed. The results showed a significant increase in dendritic intersections, branching points and dendritic processes arising from the soma of amygdaloid neurons in CTR treated rats especially in the 100 mg/kg group of rats, compared with age-matched saline controls. This improved dendritic arborization of amygdaloid neurons correlates with the increased passive avoidance learning and memory in the CTR treated rats as reported earlier. The results suggest that Clitoria ternatea aqueous root extract enhances memory by increasing the functional growth of neurons of the amygdala.

Administration, Oral↗

PubMed1998

Differences in active avoidance behaviour of hypoactive and hyperactive rats subjected to immobilisation stress.

Open field activity was studied in Wistar rats. Animals with low scores of ambulatory and rearing behaviours were grouped as hypoactive and those with high scores as hyperactive. Acquisition of active avoidance learning in a shuttle box was studied in the two groups. Hyperactive rats in contrast to hypoactive rats showed a better acquisition of avoidance learning. Learning was suppressed in both groups by domperidone, but was facilitated by immobilisation stress in the hypoactive group only. The two groups did not differ in the basal and stress evoked heart rates. These observations suggest that immobilisation stress favours enhancement of the dopaminergic related behaviour like avoidance learning in hypoactive rats.

Animals↗

PubMed1981

Involvement of the amygdala in the effect of antidepressants on the passive avoidance deficit in bulbectomised rats.

In the present study the role of the amygdala is demonstrated in the effect of antidepressant drugs on passive avoidance learning in bulbectomised rats. Imipramine, amitriptyline, or fluoxetine injected bilaterally (2 X 10 microgram) into the medial part of the amygdala improves passive avoidance learning by bulbectomised rats. Systemic pretreatment with metergoline attenuates the effect of local imipramine or fluoxetine injection. Microinjection of serotonin but not noradrenaline into the amygdala improves passive avoidance learning by bulbectomised rats. The relevance of the amygdala in the behavioral effects of antidepressants in animals is discussed.

Amitriptyline↗

PubMed1981

Passive avoidance behavior: opposite effects of oxytocin analogs with agonist and antagonist properties.

Deamino-6-carba-oxytoxin (dC60), a potent oxytocin analog considered to be resistant to some of the physiologically significant enzymic systems, and N-alpha-acetyl-[2-O-methyltyrosine]oxytocin (AMTO), an analog acting as a competitive inhibitor of oxytocin on the rat uterus, were studied in rats trained in a passive avoidance task. Subcutaneous administration of dC60 (5-50 microgram . kg-1) during different phases of the passive avoidance learning paradigm attenuated avoidance latencies; the results indicated that the drug induced state-dependent learning. AMTO (5-20 microgram . kg-1) enhanced avoidance latencies when administered subcutaneously before training trials and/or before retention test trials. This effect occurred in both males and females. The analogs did not influence exploratory behavior in open field. The results suggest that oxytoxin, in contrast to vasopressin, may impair memory processes. However, both analogs failed to influence the passive avoidance response when administered after training. This finding indicates that dC60 and AMTO did not influence the mechanism of memory consolidation whereas vasopressin and oxytoxin had a marked effect.

Animals↗

PubMedDate not supplied

[The study of individual differences as a method for dividing into stages the acquisition of a complex reflex].

Two-way active avoidance learning is a complex task characterized by a high level of interindividual variability. We have demonstrated in our previous paper that rats with different rate of learning vary in expression of freezing responses, which reflects a conflict tendency not to re-enter the previous chock compartment [4]. In the present work we analyzed as main indices the proportions of avoidance, rapid escape, and freezing responses and their distribution within a session. Sequences of occurrence of these three types of responses were examined in groups of rats with different success of avoidance learning. The obtained results confirmed a hypothesis that overcoming the conflict tendency was a separate stage of learning which preceded avoidance response appearance and subsequent stabilization. Only in rats which failed to learn and develop avoidance responses within the first session, freezing responses were observed in successive session being indicative of reappearance of the conflict tendency. The intensity of the conflict tendency did not depend on the type of the first response of an animal (fleeing or freezing) to an unexpected aversive stimulus.

Animals↗