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PubMed1996

Comparison of the effects of typical and atypical anxiolytics on learning in monkeys and rats.

Atypical anxiolytics such buspirone have been reported to produce fewer disruptive effects on complex behaviors than some typical anxiolytics from the benzodiazepine class. To extend this analysis, several drugs from both drug classes were directly compared in two species (rhesus monkeys and rats) using a repeated-acquisition procedure. In monkeys responding under a multiple schedule of reinforcement consisting of acquisition (learning) and performance components, buspirone (0.032-0.52 mg/kg), 8-hydroxy-dipropylaminotetralin (8-OH-DPAT;0.032-0-56 mg/kg), chlordiazepoxide (CDZP; 1-56 mg/kg) and alprazolam (0.032-0.32 mg/kg) produced dose-dependent decreases in overall response rate in all subjects. However, with buspirone and 8-OH-DPAT, these rate-decreasing effects occurred in acquisition at lower doses than in performance. The effects on overall accuracy (i.e., percent errors) in monkeys were variable across drugs and drug classes. Both 8-OH-DPAT and alprazolam produced large increases in percent errors in acquisition at doses that had little or no effect on errors in performance. Buspirone also had differential effects on percent errors across components, but the error-increasing effects in acquisition were smaller. CDZP administered either orally or intramuscularly produced only small increases in errors, and these occurred at doses that substantially decreased the overall rate of responding in both components of the multiple schedule. In rats responding under a repeated-acquisition procedure, buspirone (1-5.6 mg/kg), 8-OH-DPAT (0.056-3.2 mg/kg) and CDZP (1.8-32 mg/kg) produced dose-dependent decreases in overall response rate. Similar to acquisition data in monkeys, buspirone and 8-OH-DPAT also increased percent errors to a greater extent than CDZP. These data indicate that learning is sensitive to disruption by drugs with 5-HT1A agonist properties, and that atypical anxiolytics with 5-HT1A agonist properties are no less disruptive to "cognitive" processes than typical anxiolytics such as the benzodiazepine alprazolam.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2001

Chronic amphetamine exposure during the preweanling period does not affect avoidance learning or novelty-seeking of adult rats.

The purpose of the present study was to determine whether exposure to amphetamine during the preweanling period would impact the learning or reward processes of rats tested in adulthood. In three experiments we examined whether amphetamine treatment (0-10 mg/kg per day) on postnatal days 11-17 altered the subsequent performance of adult Sprague-Dawley rats on a step-down passive avoidance, active avoidance, or novelty-seeking task. There was no evidence that postnatal amphetamine exposure affected performance on any of these tasks. These results suggest that the long-term impact of pre- and postnatal psychostimulant exposure differs, because in utero stimulant treatment is known to produce learning deficits and decrease reinforcement efficacy of rats tested in adulthood.

Adrenergic Agents↗
PubMed1964

SELECTIVE PUNISHMENT OF CONCURRENT PROGRESSIVE RATIO BEHAVIOR.

Key pecking of pigeons was reinforced with grain on a progressive ratio schedule during the presence of either of two key colors. Under one color, all responses were shocked; under the other color, responses were not shocked. A single response on a second key switched the key color and reset the progressive ratio, provided that the first step of the progressive ratio had been completed. A preference developed for the longer ratios of the progressive ratio under the non-shock key color. When the severity of punishment suppressed responding under the key color correlated with shock, the subjects continued to switch to the shock condition after a moderate degree of responding under the non-shock condition. Severe punishment also resulted in frequent, ineffective responses on the switching key and extended pausing under the key color associated with shock.

Animals↗
PubMed1970

Instrumental conditioning of the rat cardiac control systems.

The PR, PP, and RR intervals of the rat EKG were instrumentally conditioned using a variety of reinforcement schedules under computer control. The PR and PP intervals could be conditioned independently. Individual rats demonstrated either a steady shift of their response distribution or an abrupt change of an all-or-none variety. Some response distributions shifted continuously; others, through the growth of new response patterns in a manner reminiscent of hypothesis-testing behavior of human subjects. A study of the effects of single reinforcements showed that each reinforcement contributed to the learning behavior of the subject, in a well-defined but nonlinear fashion.

Animals↗
PubMed1998

Binocular behavior of split-brain cats which have previously learned monocularly opposite visual discriminations.

Twelve adult split-brain cats were tested binocularly in visual tasks which had been previously learned monocularly in a two-choice paradigm. Eight experimental cats learned two opposite tasks with two eyes because contingencies of reinforcement changed with the open eye. Four control cats learned the same tasks but contingencies of reinforcement did not change with the open eye and therefore they learned the same problems with the two eyes. Thereafter, cats were submitted binocularly to the same tasks but in a free-choice paradigm. Experimental cats showed extinction of the discriminative response in 12 out of 16 binocular testings; in four the extinction criterion was not reached. In control cats no extinction behavior was observed in seven out of eight testings. It is suggested that extinction of the discriminative response in experimental cats could be caused by an inhibitory effect build-up because the two hemispheres attempted to control binocular behavior in opposite ways. Alternatively, these cats may develop a response alternative to discrimination in which one hemisphere takes the control of subcortical motor and/or attentional centers. In four testings no extinction was recorded for experimental cats and it is likely that control of those centers shifted from one hemisphere to the other every few trials.

Animals↗
PubMedDate not supplied

[The action of tropic adenohypophyseal hormones when administered intraventricularly on rat behavioral reactions].

In experiments on rats the influence was studied of tropic hormones of adenohypophysis--somatotropin, thyrotropin and adrenocorticotropin (STH, ThTN and ACTH respectively) on the elaboration and extinction of conditioned reaction of active avoidance (CRAA) in Y-maze and behaviour in the open field under microinjections of hormones into the brain lateral ventricle (0.001-0.002 ME). It has been shown that all studied hormones improve animals learning at negative pain reinforcement; ThTH and ACTH retard it in contrast to STH, which accelerates the extinction of the elaborated CRAA; tropic hormones exert differentiated influence on rats behaviour in the open field. No distinct correlation was found between behavioural manifestation and the level of catecholamines in the rats hypothalamus.

Adrenocorticotropic Hormone↗
PubMed1993

Amygdala-hypothalamic control of feeding behavior in monkey: single cell responses before and after reversible blockade of temporal cortex or amygdala projections.

Single unit activity in the monkey amygdala and the lateral hypothalamic area was recorded during an operant feeding task. The task required discrimination of food, non-food, rewarding, aversive, novel, and familiar objects. Correct discriminations were rewarded with food or juice. Some amygdala neurons responded to the sight of objects in a graded manner that depended on the degree of affective significance of the object. Some neurons in the lateral hypothalamus responded to reward predicting objects, such as the sight of some non-food item that had been associated with juice reward. Neuronal responses to the sight of objects were influenced by extinction or reversal tests. Responses in the amygdala depended on extent of the affect or value of the reward and responses in the lateral hypothalamus depended on positive reinforcement. Information processing in the inferotemporal cortex--amygdala--lateral hypothalamus axis was identified by reversible changes induced in the temporal cortex or amygdala by cooling. The results suggest that the amygdala contributes to stimulus--affect associations and that the lateral hypothalamus is related directly to the initiation or termination of feeding through learning of stimulus-reinforcement association and/or maintenance of homeostasis. In addition the results suggest that the amygdala does more sensory processing than the lateral hypothalamus.

Amygdala↗
PubMed2002

Web journaling. Using informational technology to teach reflective practice.

Reflection is a process by which we think about experiences and relieve them. Web journaling is a tool that gives students opportunities to use reflection when they are away from the immediate clinical environment. Through such reflection the student's personal knowledge that informs their practice is revealed. The revelation of personal knowledge is key to structuring subsequent faculty guidance. The web journal is a vehicle for student/faculty dialogue aimed at expanding both the faculty's responses to students' learning needs and the students' responses to persons in their care. Questions formulated in the dialogue direct the student's web-based search for new information. Faculty guidance subsequently focuses on the student's decisions regarding the use of information to direct clinical practice. Web journaling done over several nursing courses reinforces a model of learning, which is increasingly more deliberative and intentional. Web journaling may contribute to the development of practice throughout a nursing career because it becomes a way for self-directed learning.

Attitude of Health Personnel↗
PubMed2001

Unaltered radial maze performance and brain acetylcholine of the endothelial nitric oxide synthase knockout mouse.

Proceeding from previous findings of a beneficial effect of endothelial nitric oxide synthase (eNOS) gene inactivation on negatively reinforced water maze performance, we asked whether this improvement in place learning capacities also holds for a positively reinforced radial maze task. Unlike its beneficial effects on the water maze task, eNOS gene inactivation did not facilitate radial maze performance. The acquisition performance over the days of place learning did not differ between eNOS knockout (eNOS-/-) and wild-type mice (eNOS+/+). eNOS-/- mice displayed a slight and eNOS+/+ mice a more severe working memory deficit in the place learning version of the radial maze compared to the genetic background C57BL/6 strain. Possible differential effects of eNOS inactivation, related to differences in reinforcement contingencies between the Morris water maze and radial maze tasks, behavioral strategy requirements, or to different emotional and physiological concomitants inherent in the two tasks are discussed. These task-unique characteristics might be differentially affected by the reported anxiogenic and hypertensional effects of eNOS gene inactivation. Post-mortem determination of acetylcholine concentrations in diverse brain structures revealed that acetylcholine and choline contents were not different between eNOS-/- and eNOS+/+ mice, but were increased in eNOS+/+ mice compared to C57BL/6 mice in the frontal cortex. Our findings demonstrate that phenotyping of learning and memory capacities should not rely on one learning task only, but should include tasks employing both negative and positive reinforcement contingencies in order to allow valid statements regarding differences in learning capacities between rodent strains.

Acetylcholine↗
PubMed2002

Multiple 5-HT receptors are involved in the effects of acute MDMA treatment: studies on locomotor activity and responding for conditioned reinforcement.

RATIONALE: Responding for conditioned reinforcement is increased by the dopamine releasing agent amphetamine, but reduced by drugs that enhance serotonin (5-HT) function. The amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) releases both monoamines. OBJECTIVES: The primary purpose of this study was to examine the effects of MDMA on responding for conditioned reinforcement as well as on locomotor activity. The roles of several 5-HT receptor sub-types in mediating these behavioural effects of MDMA were also examined. METHODS: Locomotion was measured in photocell activity monitors. For conditioned reinforcement experiments thirsty rats learned to associate a conditioned stimulus (CS) with water in operant chambers. Subsequently, two response levers were available; responding on one lever delivered the CS, while responding on the second lever had no consequences. Drug effects on this operant response were measured. RESULTS: MDMA dose-dependently increased locomotion but reduced responding for conditioned reinforcement. This latter effect differs from that induced by amphetamine, which potentiates conditioned reinforcement responding. The stimulant effect of MDMA was attenuated by GR127935 and ketanserin, indicating facilitatory roles of 5-HT(1B) and 5-HT(2A) receptors in mediating this effect. The 5-HT(2C) antagonist SB242084 enhanced the stimulant effect of MDMA. Only SB242084 attenuated the suppressant effect of MDMA on responding for conditioned reinforcement. CONCLUSIONS: The results show that 5-HT(2A) and 5-HT(1B/1D) receptors play a facilitatory role in mediating the stimulant effect of MDMA, whereas 5-HT(2C) receptors are inhibitory. Activation of 5-HT(2C) receptors also contributes to the deficit in operant responding. Multiple 5-HT receptor sub-types appear to contribute to the behavioural effects of MDMA.

3,4-Methylenedioxyamphetamine↗