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At least 775 records · Page 43Linked to original sources
PubMed2006

Subcortical deafferentation impairs behavioral reinforcement of long-term potentiation in the dentate gyrus of freely moving rats.

Long-term potentiation is a form of neural functional plasticity which has been related with memory formation and recovery of function after brain injury. Previous studies have shown that a transient early-long-term potentiation can be prolonged by direct stimulation of distinct brain areas, or behavioral stimuli with a high motivational content. The basolateral amygdala and other subcortical structures, like the medial septum and the locus coeruleus, are involved in mediating the reinforcing effect. We have previously shown that the lesion of the fimbria-fornix--the main entrance of subcortical afferents to the hippocampus--abolishes the reinforcing basolateral amygdala-effects on long-term potentiation in the dentate gyrus in vivo. It remains to be investigated, however, if such subcortical afferents may also be important for behavioral reinforcement of long-term potentiation. Young-adult (8 weeks) Sprague-Dawley male rats were fimbria-fornix-transected under anesthesia, and electrodes were implanted at the dentate gyrus and the perforant path. One week after surgery the freely moving animals were studied. Fimbria-fornix-lesion reduced the ability of the animals to develop long-term potentiation when a short pulse duration was used for tetanization (0.1 ms per half-wave of a biphasic stimulus), whereas increasing the pulse duration to 0.2 ms per half-wave during tetanization resulted in a transient early-long-term potentiation lasting about 4 h in the lesioned animals, comparable to that obtained in non-lesioned or sham-operated control rats. In water-deprived (24 h) control animals, i.e. in non-lesioned and sham-operated rats, early-long-term potentiation could be behaviorally reinforced by drinking 15 min after tetanization. However, in fimbria-fornix-lesioned animals long-term potentiation-reinforcement by drinking was not detected. This result indicates that the effect of behavioral-motivational stimuli to reinforce long-term potentiation is mediated by subcortical, heterosynaptic afferents.

Afferent Pathways↗
PubMed1997

Interactions between self and external reinforcement in predicting depressive symptoms.

A low rate of self-reinforcement has been argued by a number of theorists to be implicated in the aetiology and maintenance of unipolar depression. This paper examines the relationship between dispositional rates of self-reinforcement, as assessed by the Frequency of Self-Reinforcement Questionnaire (Heiby, 1982, Behaviour Research and Therapy, 20, 397-401), external sources of reward and punishment, extraversion, neuroticism, and depression. Using a hierarchical regression methodology (N = 366), evidence was found to support the view that self-reinforcement is a construct distinct from other major personality variables, and that it has both direct and moderational effects on depression. The results did not support the view that extraversion is associated with depression either as a main effect or in interaction with neuroticism. It is argued that despite the significant results, the main and interactional influences of self-reinforcement on depression are minor and that the important role of external sources of reinforcement and punishment should not be disregarded.

Adult↗
PubMed2002

The reinforcing effects of acetaldehyde in the posterior ventral tegmental area of alcohol-preferring rats.

Acetaldehyde (ACD), the first metabolite of ethanol, is a biologically active compound, which may mediate some of the reinforcing, behavioral and neurotoxic effects of ethanol. The objective of this study was to test the hypothesis that ACD is reinforcing within the mesolimbic system. The intracranial self-administration (ICSA) technique was employed to determine whether ACD was reinforcing in the posterior ventral tegmental area (VTA), a site that supports the reinforcing actions of ethanol. Adult female alcohol-preferring (P) rats were implanted with guide cannulae aimed at the posterior VTA. Subjects were placed in two-lever operant chambers 7-10 days after surgery. Responding on the "active lever" on a fixed ratio 1 (FR1) schedule of reinforcement caused the delivery of 100 nl of infusate, whereas responses on the "inactive lever" were without consequences. Rats were assigned to one of five groups that self-administered either artificial cerebrospinal fluid (aCSF) throughout all eight sessions (4 h in duration) or 3- and 6-, 11- and 23-, 45- and 90- or 180- and 360-microM ACD for the eight sessions, with the lower concentration of ACD given for the initial four sessions and the higher concentration of ACD given for the last four sessions. A second experiment examined the acquisition (first four sessions), extinction (aCSF in sessions 5 and 6) and reinstatement using 90-microM ACD. A third experiment examined the effects of extending the time-out period (from 5 to 55 s) on the number and pattern of infusions of 23-microM ACD. Adult P rats readily self-administered 6-90-microM ACD and discriminated between the active and inactive levers. Furthermore, rats self-administering 90-microM ACD also demonstrated extinction behavior when aCSF was substituted for ACD and gradually reinstated active lever responding when ACD was reintroduced. P rats maintained similar numbers of infusions and infusion patterns under both time-out schedules. Overall, the data indicate that ACD is a potent reinforcer within the posterior VTA of the P rat.

Acetaldehyde↗
PubMedDate not supplied

Cellular investigations of behavioral reinforcement.

Using the hippocampal-slice preparation, we attempted to demonstrate operant conditioning of pyramidal cell activity using local micropressure applications of transmitters and drugs as reinforcement; the same injections administered independently of bursting provided a control for direct pharmacological stimulation or facilitation of firing. The results suggested that the spontaneous bursting of individual CA1 pyramidal neurons may be reinforced with activity-contingent injections of dopamine and cocaine, whereas, CA3-bursting responses may be reinforced with contingently-applied dynorphin A. We sought to confirm these indications of cellular reinforcement at the behavioral level in studies of hippocampal self-administration (despite the fact that the hippocampus has been ignored as a brain site for chemical self-administration experiments). The results suggested that dynorphin A is a powerful reinforcer of hippocampal self-administration behavior when injected in the CA3 field; experiments still in progress suggest that dopamine can reinforce self-administration behavior when injected in the CA1 field. Successful prediction of new behavioral data from operant-conditioning data at the cellular level helps to validate the cellular data by providing suggestive evidence of interrelationship between cellular and behavioral operant conditioning processes.

Animals↗
PubMedDate not supplied

Subtypes of dopamine receptors involved in the mechanism of reinforcement.

Advancement in the study of receptors for neurotransmitters facilitated the analysis of neural mechanisms underlying reinforcement. Two subtypes of dopamine receptors, D1 and D2, play distinct roles in producing reinforcing effects. Experiments using SCH 23390 suggest that the reinforcing effects of food, water, saccharin, heroin and brain stimulation all critically depend on the activation of D1 dopamine receptors, particularly those in the nucleus accumbens and the ventral tegmental area. Raclopride, a D2 dopamine antagonist, also reduced bar-pressing responses for food, heroin, and brain stimulation. Thus, both D1 and D2 receptors seem to be involved in the reinforcement mechanisms. There were some differences between D1 and D2 dopamine antagonists in the manner of reducing operant responding. It appears that D1 receptors are related to the efficacy of reinforcements while D2 receptors are related to the type of reinforcers.

Animals↗
PubMed2002

Differences between appetitive and aversive reinforcement on reorientation in a spatial working memory task.

Tasks using appetitive reinforcers show that following disorientation rats use the shape of an arena to reorient, and cannot distinguish two geometrically similar corners to obtain a reward, despite the presence of a prominent visual cue that provides information to differentiate the two corners. Other studies show that disorientation impairs performance on certain appetitive, but not aversive, tasks. This study evaluated whether rats would make similar geometric errors in a working memory task that used aversive reinforcement. We hypothesized that in a task that used aversive reinforcement rats that were initially disoriented would not reorient by arena shape and thus make similar geometric errors. Tests were performed in a rectangular arena having one polarizing cue. In the appetitive condition water consumption was the reward. The aversive condition was a water maze task with reinforcement provided by escape to a hidden platform. In the aversive condition rats returned to the reinforced corner significantly more often than in the dry condition, and did not favor the diagonally opposite corner. Results show that rats can use cues besides arena shape to reorient in an aversive reinforcement condition. These findings may also reflect different strategies, with an escape/homing strategy in the wet condition and a foraging strategy in the dry condition.

Animals↗
PubMed2002

Analysis of the reinforcing and subjective effects of different doses of nitrous oxide using a free-choice procedure.

The reinforcing and subjective effects of five doses of nitrous oxide (0, 10, 20, 30, 40% N(2)O in O(2)) were studied in 20 non-drug-abusers using a free-choice procedure. During each of five sessions, subjects sampled a dose of N(2)O and 100% O(2) (placebo) for 10 min each. Later they chose nine times, once every 5 min, among N(2)O (e.g. 'Agent A'), placebo (e.g. 'Agent B'), or a no-drug option. Mean preference ratios (N(2)O choices/[N(2)O choices+placebo choices]) and total N(2)O choice increased with increasing N(2)O dose. Individual preference ratios suggested that at least one active dose of N(2)O functioned as a reinforcer in 80% of subjects, and the doses that functioned as reinforcers varied across subjects. N(2)O choice was positively correlated with end-of-session and post-session ratings of N(2)O liking and of wanting to inhale N(2)O again, but not with ratings of those effects during sampling. Placebo was chosen significantly less than the no-drug option, even though both were 100% O(2). More robust reinforcing effects of N(2)O were observed in this subject population than in previous studies. Choice data emphasize the importance of examining a range of doses, and of examining those effects within-subject, when assessing reinforcing effects of drugs. Inclusion of the no-drug option eliminated the 'forced' choice of placebo, making preference ratios easier to interpret than in previous, forced-choice procedures. Reinforcing effects were more correlated with subjective effects assessed after the session than with subjective effects obtained while subjects were under the influence of the drug.

Adult↗
PubMedDate not supplied

The development of a reinforcer choice assessment scale for persons with severe and profound mental retardation.

Reinforcement is a cornerstone for treating adaptive skills and eliminating problem behaviors for persons evincing mental retardation. To effectively use reinforcement, professionals must find reinforcers that are most effective for each individual. Establishing reinforcers is particularly important for persons functioning in the severe and profound ranges of mental retardation as reinforcers are often difficult to identify in this population. The current study aimed at developing a reinforcer rating scale that-would have applicability on a broad clinical basis, looking specifically at the psychometric properties of the scale.

Adult↗
PubMed1998

Context reinforcement degrades discriminative control: a memory approach.

This study measured effects of context reinforcement on a visual discrimination. Five pigeons responded to 1 key in the presence of 6 shorter wavelengths and to another key for 6 longer wavelengths. Psychometric functions provided measures of discriminative sensitivity (d') and overall stimulus control. Sensitivity and control were slightly but significantly better when 20% of correct choices yielded reinforcement than when 5% did. Reinforcement of pecks to the sample stimulus reduced control substantially and sensitivity slightly; noncontingent reinforcement during intertrial intervals also reduced control, whether such reinforcement was signaled or not. Accuracy was excellent during an extinction session, but it fell substantially when reinforcement for sample pecks was added during choice extinction. Simulations based on a memory model of the discrimination process reproduced most of the experimental findings.

Animals↗
PubMed1979

Aspects of the reinforcer learned in second-order Pavlovian conditioning.

Four experiments used an autoshaping procedure in pigeons to explore learning about the reinforcer in a second-order conditioning paradigm. Experiment 1 conditioned two visual second-order stimuli (S2), using as reinforcers two visual first-order stimuli (S1), each of which had previously been paired with food. Animals for which the S2 stimuli were each consistently paired with one particular S1 developed second-order responding more rapidly than did animals for which the identity of S1 varied from trial to trial. Moreover, following consistent pairings, extinction of an S1 had a depressive effect upon second-order responding which was peculiar to the S2 with which it had been paired. Both results suggest that in this preparation the organism identifies a particular S1 as the reinforcer for each S2. The remaining experiments examined the details of that identification. A compound S1, itself composed of two separable elements, was used to reinforce an S2. Subsequent extinction of either element of S1 led to a depression in the responding to S2, which indicates that both elements were involved in the second-order conditioning. Moreover, the use of several complex discriminations, which produced different behavior to S1 and to its elements, suggested that the organism had associated the S2 with the compound S1 rather than with its separate elements. However, even complete extinction of the response to S1 left some residual behavior to S2, which indicates that a portion of the second-order conditioning is independent of the current state of the reinforcer. These results demonstrate that in some situations the organism associates a conditioned stimulus with a rich representation of the reinforcer.

Animals↗
PubMed2004

Reinforced variability in animals and people: implications for adaptive action.

Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action.

Animals↗
PubMed1994

The role of probability of reinforcement in models of choice.

A general account of choice behavior in animals, the cumulative effects model, has been proposed by Davis, Staddon, Machado, and Palmer (1993). Its basic assumptions are that choice occurs in an all-or-none fashion for the response alternative with the highest probability of reinforcement and that the probability of reinforcement for each response alternative is calculated from the entire history of training (total number of reinforced responses/total number of reinforced and nonreinforced responses). The model's reliance on probability of reinforcement as the fundamental variable controlling choice behavior subjects the cumulative effects model to the same criticisms as have been directed toward other related models of choice, notably melioration theory. Several different data sets show that the relative value of a response alternative is not predicted by the obtained probability of reinforcement associated with that alternative. Alternative approaches to choice theory are considered.

Animals↗
PubMed2005

The supramammillary nucleus mediates primary reinforcement via GABA(A) receptors.

The supramammillary nucleus (SUM), a dorsal layer of the mammillary body, has recently been implicated in positive reinforcement. The present study examined whether GABA(A) receptors in the SUM or adjacent regions are involved in primary reinforcement using intracranial self-administration procedures. Rats learned quickly to lever-press for infusions of the GABA(A) antagonist picrotoxin into the SUM. Although picrotoxin was also self-administered into the posterior hypothalamic nuclei and anterior ventral tegmental area, these regions were less responsive to lower doses of picrotoxin than the SUM. The finding that rats learned to respond selectively on the lever triggering drug infusions is consistent with picrotoxin's reinforcing effect. Coadministration of the GABA(A) agonist muscimol disrupted picrotoxin self-administration, and another GABA(A) antagonist, bicuculline, was also self-administered into the SUM; thus, the reinforcing effect of picrotoxin is mediated by GABA(A) receptors. Since rats did not self-administer the GABA(B) antagonist 2-hydroxysaclofen into the SUM, the role of GABA(B) receptors may be distinct from that of GABA(A) receptors. Pretreatment with the dopamine receptor antagonist SCH 23390 (0.05 mg/kg, i.p.) extinguished picrotoxin self-administration into the SUM, suggesting that the reinforcing effects of GABA(A) receptor blockade depend on normal dopamine transmission. In conclusion, the blockade of GABA(A) receptors in the SUM is reinforcing, and the brain 'reward' circuitry appears to be tonically inhibited via supramammillary GABA(A) receptors and more extensive than the meso-limbic dopamine system.

Animals↗
PubMed2003

Discrimination between outcomes in instrumental learning: effects of preexposure to the reinforcers.

In two experiments rats received instrumental training with two response levers, one response being reinforced by sucrose solution and the other by sucrose pellets. Prior to a test session, on which both levers were made available in the absence of reinforcement, the rats were given free access to one of the reinforcers, a procedure known to reduce its value. It was found that the rats responded at a lower rate on the lever that had produced the now-devalued reinforcer, but that this effect was substantial only in rats that had received preexposure to the two reinforcers before instrumental training was begun (Experiment 1). Experiment 2 demonstrated that this effect was obtained only when presentations of the two reinforcers were presented according to an inter-mixed schedule during preexposure. It is suggested that this result constitutes an instance of the perceptual learning effect in which intermixed preexposure to similar events enhances their discriminability.

Animals↗
PubMed1998

Reinforcement without awareness: II. Word class.

In a previous study of reinforcement without awareness by Lieberman, Sunnucks, & Kirk (this issue), subjects were told that the experiment was on ESP; two words were presented on every trial, and their task was to choose the word the experimenter was thinking of. In fact, reinforcement was contingent on the loudness of the subjects' voices when responding. They found stronger evidence for reinforcement without awareness than in many previous studies, and they attributed their success in part to the reinforcement of a response to which subjects were unlikely to attend. To explore this factor further, we again used an ESP cover story but reinforced subjects for choosing the word in each pair that contained a double letter. We found evidence of reinforcement without awareness in three experiments and also identified two factors that influence these effects: Learning did not occur if subjects (a) were encouraged to test irrelevant hypotheses, or (b) sat in an uncomfortable chair. We speculate that learning without awareness may be more likely when subjects are relaxed and that hypothesis testing and uncomfortable chairs impair such learning because they prevent relaxation.

Adult↗
PubMed1980

A comparison of passive and active music reinforcement to increase preacademic and motor skills in severely retarded children and adolescents.

Eight severely retarded subjects were each taught two behaviors with contingent music listening (passive reinforcement) and contingent rhythm instrument playing (active reinforcement) to determine which type of reinforcement was more effective. A variation of the multiple baseline design was used in which a baseline condition preceded and followed two treatment conditions, passive and active music. Treatment conditions for each behavior were terminated at criterion or after the subject failed to meet criterion. Criterion was defined as an increase of 25% above the baseline mean for three consecutive sessions. An F test was performed on the sessions to criterion and the behavior frequencies under each reinforcement condition. Results indicated that both passive and active music reinforcement had a positive effect even though no significant differences were discerned between the two reinforcers for either variable. These findings were consistent with the previous limited study in this area.

Adolescent↗
PubMedDate not supplied

Reinforced and nonreinforced head-turn responses of infants as a function of stimulus bandwidth.

The purpose of this study was to investigate auditory-stimulus effects on head-turn response behavior of infants under conditions where responses were either reinforced or not reinforced with a visual stimulus. The auditory stimuli contained different frequency bandwidths between 2000 and 4000 Hz. The stimulus with the widest bandwidth resulted in more responses than the other two stimuli in the no-reinforcement condition. When conditioning was established and all responses were visually reinforced, there was no difference in response behavior among stimulus groups for either suprathreshold or threshold stimulation. These findings have implications for clinical assessment using visual reinforcement audiometry. Results suggest that bandwidth characteristics of the auditory stimulus have no influence on response behavior of infants providing conditioning can be established and maintained through the use of visual reinforcement.

Audiometry↗
PubMed1988

Effect of reinforcement on infants' performance in a preferential looking acuity task.

Two experiments examined the effect of reinforcement on infants' performance in a preferential looking acuity task. In experiment 1, performance of 3- and 5-month-old infants was assessed under three conditions. In one condition, reinforcement was contingent upon performance. In another, no reinforcement was provided. In the last condition, reinforcement was provided, but it was not contingent upon performance. Similar performance was observed in all three conditions. In experiment 2, 7-month-olds were tested in the first and second conditions. No differences in performance were observed between these two groups. Thus, the reinforcement used in preferential looking measurements does not appear to improve performance significantly for 3- to 7-month-old infants. Several interpretations of these results are presented. The most plausible is that performance under nonreinforced conditions is already nearly optimal, so the addition of reinforcement has little impact. General implications for estimates of infant visual sensitivity in the laboratory and clinic are discussed.

Humans↗