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PubMed1981

Suppression of active sleep by chronic treatment with chlorimipramine during early postnatal development: effects upon adult sleep and behavior in the rat.

In an attempt to study the possible role of active sleep in brain development, male rats were injected twice daily with chlorimipramine, a potent monoamine reuptake blocker, from 1 week to 3 weeks of postnatal age. AS was reduced to less than 10% of total sleep time, the level found in mature rats. Most of the AS reduction was compensated for by quiet sleep but a slight increase in wakefulness also occurred, owing to brief interruptions of sleep at times when AS was expected. In adulthood, the AS-deprived rats showed a higher percentage of AS than did the controls, due to an increase in frequency and duration of AS epochs. Moreover, many of the epochs contained abnormally frequent and strong jerky body movements and rapid-eye-movements, reminiscent of neonatal AS patterns. In addition, the amplitude of hippocampal theta waves during AS was greater than in control rats. The chlorimipramine-treated rats also showed behavioral abnormalities in later life. On the open field test exploratory behavior was much reduced, while increased rearing and defecation occurred. Masculine sexual performance was severely deficient, primarily due to the low level of intromissions and ejaculations. Experimental animals performed less efficiently than controls on a temporal learning task (differential reinforcement of low response rate) and responded more rapidly on a spatial task (left-right alternation learning). These results demonstrate that early interference with the functioning of monoaminergic systems can have long-lasting physiological and behavioral consequences. Furthermore, they are consistent with the hypothesis that AS is an important factor in normal brain development.

Aggression↗
PubMed2005

Variations in unconditioned stimulus processing in unblocking.

Three experiments examined the mechanisms by which downward shifts in reinforcer value influence learning in appetitive unblocking procedures. The downward shift was accomplished by omitting the 2nd of a 2-reinforcer sequence (food-food or food-sucrose). Performance of normal rats was compared with that of rats with lesions of the central nucleus of the amygdala, which are thought to interfere with surprise-induced enhancements of event processing. The results suggested that, in normal rats, omission of the 2nd reinforcer enhanced processing of the 1st reinforcer rather than processing of the conditioned stimuli and that lesions of the central nucleus eliminated this enhancement. The roles of reinforcement error signals in conditioning are discussed.

Amygdala↗
PubMed2006

Dynorphin A (1-13) and responsiveness of the newborn rat to a surrogate nipple: immediate behavioral consequences and reinforcement effects in conditioning.

The role of endogenous opioid system in learning (Pavlovian conditioning) and reinforcement was studied in newborn rats by pairing central injection of dynorphin A (1-13), an endogenous ligand with high affinity for kappa opioid receptors, with a surrogate nipple. For conditioning, the nipple served as the conditioned stimulus and dynorphin as the unconditioned stimulus. Dynorphin was found to elicit an immediate unconditioned, dose-dependent increase in the neonatal responsiveness to a surrogate nipple providing water, an effect apparently mediated through the kappa opioid receptors. This immediate effect of dynorphin was evident in the context of suckling behavior but not in the context of adult-like drinking when water was delivered through an intra-oral cannula. One hour after injection, the unconditioned stimulatory effect of dynorphin had dissipated and no longer affected responsiveness to the nipple. However, pairing of centrally injected dynorphin and suckling on a nipple delivering water substantially enhanced responsiveness to a nipple 1h later. This suggested conditioning, and hence reinforcement, by the centrally injected dynorphin. The conditioned sustained nipple attachment was mediated through both kappa and micro opioid receptors. These experiments confirm a central role for the brain opioid systems in reinforcement of neonatal behavior on the nipple.

Animals↗
PubMed1963

Reinforcement of mediating behavior on a spaced-responding schedule.

This paper describes a procedure for gaining experimental control over mediating behavior on a spaced-responding schedule of food reinforcement. Three rats, food-deprived, were trained on a DRL 16 sec schedule of food reinforcement. Then, a concurrent schedule of food reinforcement was introduced on a second (mediating) lever, such that the first response to occur on the mediating lever, after the DRL interval had timed out, was reinforced with food, as was the next response to occur on the DRL lever. Reinforcement via the mediating lever became a discriminative stimulus for a food-reinforcement opportunity on the DRL lever. Next, food reinforcement for the mediating behavior was replaced by a conditioned reinforcer consisting of onset of a buzzer signaling timing-out of the DRL interval. Under these conditions, chaining of behavior on the two levers was strong, and timing on the DRL lever was more accurate than under ordinary DRL conditions. As the DRL requirement was lengthened from 16 sec to 24 sec to 60 sec, mediating behavior weakened slightly. When the inter-response requirement for food reinforcement on the DRL lever was made shorter than the inter-response requirement for conditioned reinforcement on the mediating lever, the mediating behavior extinguished. Performance in the experiment was analyzed into a four-component chain, and the factors contributing to the maintenance, and later extinction, of mediating behavior are discussed.

Animals↗
PubMed1993

Sequence-specific effects of neurokinin substance P on memory, reinforcement, and brain dopamine activity.

There is ample evidence that the neurokinin substance P (SP) can have neurotrophic as well as memory-promoting effects. This paper outlines a recent series of experiments dealing with the effects of SP and its N- and C-terminal fragments on memory, reinforcement, and brain monoamine metabolism. It was shown that SP, when applied peripherally (IP), promotes memory (inhibitory avoidance learning) and is reinforcing (place preference task) at the same dose of 37 nmol/kg. Most important, however, is the finding that these effects seemed to be encoded by different SP sequences, since the N-terminal SP1-7 (185 nmol/kg) enhanced memory, whereas C-terminal hepta- and hexapeptide sequences of SP proved to be reinforcing in a dose equimolar to SP. These differential behavioral effects were paralleled by selective and site-specific changes in dopamine (DA) activity, as both SP and its C-, but not N-terminus, increased extracellular DA in the nucleus accumbens (NAc), but not in the neostriatum. The neurochemical changes lasted at least 2 h after injection. These results show that the reinforcing action of peripheral administered SP may be mediated by its C-terminal sequence, and that this effect could be related to DA activity in the NAc. Direct application of SP (0.74 pmol) into the region of the nucleus basalis magnocellularis (NBM) was also memory-promoting and reinforcing, and again, these effects were differentially produced by the N-terminus and C-terminus, supporting the proposed structure-activity relationship for SP's effects on memory and reinfrocement. These results may provide a hypothetical link between the memory-modulating and reinforcing effects of SP and the impairment in associative functioning accompanying certain neurodegenerative processes.

Amino Acid Sequence↗
PubMed2003

An evaluation of the integration of non-traditional learning tools into a community based breast and cervical cancer education program: the Witness Project of Buffalo.

BACKGROUND: Breast and cervical cancer continue to represent major health challenges for African American women. among Caucasian women. The underlying reasons for this disparity are multifactorial and include lack of education and awareness of screening and early detection. Traditional educational methods have enjoyed varied success in the African American community and spawned development of novel educational approaches. Community based education programs employing a variety of educational models have been introduced. Successful programs must train and provide lay community members with the tools necessary to deliver strong educational programs. METHODS: The Witness Project is a theory-based, breast and cervical cancer educational program, delivered by African American women, that stresses the importance of early detection and screening to improve survival and teaches women how to perform breast self examination. Implementing this program in the Buffalo Witness Project of Buffalo required several modifications in the curriculum, integration of non-traditional learning tools and focused training in clinical study participation. The educational approaches utilized included repetition, modeling, building comprehension, reinforcement, hands on learning, a social story on breast health for African American women, and role play conversations about breast and cervical health and support. RESULTS: Incorporating non-traditional educational approaches into the Witness Project training resulted in a 79% improvement in the number of women who mastered the didactic information. A seventy-two percent study participation rate was achieved by educating the community organizations that hosted Witness Project programs about the informed consent process and study participation. CONCLUSION: Incorporating non-traditional educational approaches into community outreach programs increases training success as well as community participation.

Adult↗
PubMedDate not supplied

[Relation between the effects of the memory neuromodulator arginine-vasopressin and the levels of activity of the serotonin-, dopamine- and noradrenergic systems of the brain].

The effect of vasopressin on learning, habituation and habit recovery in rat before and after electrolytic ablation of locus coeruleus, nuclei dorsalis et medialis raphe and pars compacta substantiae nigrae was studied by behavioural methods. The rats were learned with positive reinforcement in a T-shaped maze and with negative reinforcement in a U-shaped maze. It was found that improvement of trace consolidation and acceleration of learning were in many cases dependent on the activity level of the dophaminergic, noradrenergic and to a lesser degree on that of serotoninergic brain systems.

Animals↗
PubMed1988

Preventing a feature-positive effect in pigeons.

The feature-positive effect (FPE) is a widespread and robust phenomenon in the context of discrimination learning. It refers to the fact that a distinctive feature associated with a stimulus that is reinforced leads to efficient discrimination learning, whereas the same feature associated with the nonreinforced stimulus inhibits discrimination learning. Two experiments with pigeons showed that the FPE also occurs with a simultaneous discrimination paradigm involving brief discrete trials and no intertrial intervals. A pre-training treatment unexpectedly prevented the expression of the FPE in this discrimination task. The pretraining consisted of having pigeons discriminate the feature/nonfeature visual shapes from a plain background disc. Rewarding responses to the shapes, or alternatively to the blank disc, had the same FPE-preventing effect. A reversal of a feature/nonfeature stimulus discrimination led to an analogous erasure of the FPE. The results are discussed in terms of the concurrence or interference between the various associations that the subjects formed on the basis of the different stimulus-reward correlations they experienced in the different phases of the experiments.

Animals↗
PubMed1998

Effects of retention interval on latent inhibition and perceptual learning.

Repeated, non-reinforced preexposure to a context slowed development of conditioned freezing to that context when it was subsequently paired with footshock (latent inhibition) and enhanced discriminability of that context from a similar context (perceptual learning) whether assessed by a generalization test or by explicit discrimination training. Latent inhibition was eliminated by a delay between conditioning sessions and test (Experiments 1a and 1b) and reduced by a delay between preexposure and conditioning (Experiment 2). However, perceptual learning was unaffected by either of these intervals (Experiments 1b and 2). These results are discussed in terms their impact on theories that have latent inhibition as a possible mechanism of perceptual learning, and on theories of latent inhibition that consider the retardation of conditioned responding to be the result of an acquisition failure.

Animals↗
PubMed2006

Nicotine administration enhances conditioned inhibition in rats.

The effect of nicotine on conditioned inhibition was examined using a serial feature negative discrimination task. Nicotine (0.35 mg/kg) or vehicle was administered before each of the 16 training sessions. On some trials in each session, a tone was presented and followed by food reward. On other trials, the tone was preceded by a visual stimulus and not reinforced. Nicotine-treated rats exhibited greater discrimination between the two trial types as evidenced by less frequent responding during non-reinforced trials, and learned the discrimination in fewer sessions than vehicle-treated rats. In contrast, there were no group differences in responding during the reinforced trials.

Analysis of Variance↗
PubMed2003

Differential desensitization and distribution of nicotinic acetylcholine receptor subtypes in midbrain dopamine areas.

Although many psychopharmacological factors contribute to nicotine addiction, midbrain dopaminergic systems have received much attention because of their roles in reinforcement and associative learning. It is generally thought that the mesocorticolimbic dopaminergic system is important for the acquisition of behaviors that are reinforced by the salient drives of the environment or by the inappropriate stimuli of addictive drugs. Nicotine, as obtained from tobacco, can activate nicotinic acetylcholine receptors (nAChRs) and excite midbrain neurons of the mesocorticolimbic system. Using midbrain slices from rats, wild-type mice, and genetically engineered mice, we have found differences in the nAChR currents from the ventral tegmental area (VTA) and the substantia nigra compacta (SNc). Nicotinic AChRs containing the alpha7 subunit (alpha7* nAChRs) have a low expression density. Electrophysiological analysis of nAChR currents, autoradiography of [125I]-alpha-bungarotoxin binding, and in situ hybridization revealed that alpha7* nAChRs are more highly expressed in the VTA than the SNc. In contrast, beta2* nAChRs are move evenly distributed at a higher density in both the VTA and SNc. At the concentration of nicotine obtained by tobacco smokers, the slow components of current (mainly mediated by beta2* nAChRs) become essentially desensitized. However, the minority alpha7* component of the current in the VTA/SNc is not significantly desensitized by nicotine in the range < or =100 nm. These results suggest that nicotine, as obtained from tobacco, can have multiple effects on the midbrain areas by differentially influencing dopamine neurons of the VTA and SNc and differentially desensitizing alpha7* and non-alpha7 nAChRs.

Animals↗