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PubMed1962

Electroencephalographic correlates of temporally spaced responding and avoidance behavior.

This study was undertaken to determine whether any EEG changes occurred during a multiple schedule of reinforcement consisting of repeated periods of avoidance behavior, a time-out (TO) period, and a period of differential reinforcement of low rates (DRL). The two monkeys were permanently implanted with bipolar electrodes in various subcortical areas. The EEG was recorded from these electrodes for several weeks before any behavioral training was undertaken. Training was then begun in the multiple schedule, and EEG recordings were taken frequently throughout the training period. When a stable performance level was achieved, drugs (dl-amphetamine and sodium pentobarbital) were introduced which disrupted the DRL performance but had little or no effect on avoidance behavior. The EEG recordings continued throughout these drug studies. The data indicate that the marked behavioral differences noted in each component of the schedule were not reflected in the EEG. However, the EEG did correlate with the general level of alertness of the animals during the various components. The drugs which differentially affected the behavior in the components of the schedule did not differentially affect the EEG, but they did change the brain-wave activity equally in all components. Finally, EEG changes correlated with the complex motor response of lever pressing were not observed.

Animals↗
PubMed1999

Acquisition of a fixed ratio schedule in adult male rats neonatally exposed to ethanol and/or cocaine.

Acquisition of an operant learning task for sucrose reinforcement was examined in rats after neonatal exposure to ethanol and/or cocaine. Subjects were raised using an artificial rearing procedure from postnatal days 4 to 11 and were intragastrically fed a milk diet containing either ethanol (6 g/kg/day), cocaine (60 mg/kg/day), the combination (6 g/kg/day + 60 mg/kg/day), or an isocaloric control diet. There was also a suckled sham control. Adult male offspring (postnatal day 65 to postnatal day 68) were shaped to lever press for sucrose reinforcement and then began daily 15-min sessions of fixed ratio (FR) training. The number of days to acquire an FR 20 was measured. Neonatal exposure to the ethanol/cocaine combination significantly increased the number of days to reach the FR 20. There was also a trend for fewer of these subjects to reach the FR 20, although this difference was not statistically significant. These results suggest that subjects neonatally exposed to the ethanol/cocaine combination have difficulty learning an operant task. This impairment was unique to the ethanol/cocaine combination group and suggests that polydrug exposure during development may have a more adverse outcome than exposure to ethanol or cocaine alone.

Age Factors↗
PubMedDate not supplied

[Neurobiological correlates premeditated (learned) aggression: seeking new experimental approaches].

Theoretical possibility of experimental modeling of learned (premediated) aggression developing in human after experience of aggression is considered. The sensory contact technique increases aggressiveness in male mice and allows aggressive type of behavior to be formed as a result of repeated experience of victories in daily agonistic confrontations. Some behavioral domains confirm the development of learned aggression in males similar to those in humans. The features are: repeated experience of aggression reinforced by victories; elements of learned behavior after period of confrontations; intent, measured by increase of the aggressive motivation prior agonistic confrontation; decreased emotionality estimated by parameters of open field behavior. Relevant stimuli provoke demonstration of aggression. This review summarized data on the influence of positive fighting experience in daily intermale confrontations on the behavior, neurochemistry and physiology of aggressive mice (winners). This sort of experience changes many characteristics in individual and social behaviors, these having been estimated in different tests and in varied situations. Some physiological parameters are also changed in the winners. Neurochemical data confirm the activation of brain dopaminergic systems and functional inhibition of serotonergic system in winners under influence of repeated experience of aggression. The expression of the neurochemical and behavioral changes observed in winners has been found dependent on the mouse strain and on the duration of their agonistic confrontations. Similarities in mechanisms of learned aggression in humans and mice are considered.

Aggression↗
PubMed1995

Evaluating the empirical support for the role of testosterone in the Geschwind-Behan-Galaburda model of cerebral lateralization: commentary on Bryden, McManus, and Bulman-Fleming.

The main tenet of the GBG model relates to the prenatal action of testosterone. Anomalies in cerebral dominance, immune functioning, abilities, and neural crest development are hypothesized to correlate with each other because all result from high levels of prenatal testosterone. Studies directly evaluating the effect of testosterone on these traits do not validate the model: sex ratios and animal studies suggest that testosterone has a protective, rather than facilitatory, effect on autoimmune diseases; individuals with high levels of early testosterone do not have elevated rates of left-handedness or learning disabilities. These findings reinforce Bryden et al.'s conclusions that there is little empirical support for the GBG model, and that it is wise to consider other theories in evaluating data derived from the model.

Adolescent↗
PubMed1962

Response latency as a function of amount of reinforcement.

Food-deprived rats were trained to press and hold down a telegraph key in the presence of a light. Subsequent release of the key during a tone was followed by 0.15 ml of a 20-percent sucrose solution as reinforcement. The Ss were subsequently shifted to a 0-percent and to a 5-percent solution from the 20-percent base line. The median RT and the variability of RT increased markedly as a result of the shift to the lower sucrose concentrations. For all Ss, the change in median and variability was greater for the shift to the 0-percent solution than for the shift to the 5-percent solution. It is probable that median RT and variability of RT are inversely related to amount of reinforcement.

Animals↗
PubMed1980

Discrimination and differentiation of response number in stimulus directed pecking of pigeons.

In Experiment 1, autoshaping trials terminated with food only if pigeons emitted more than a target number of responses during a trial in one condition and fewer than a target number in another. The median number of responses per trial shifted in accordance wtih the requirements. The responding of yoked-control birds that received response-independent reinforcers did not vary with the response requirements. In Experiment 2, the number of responses in autoshaping trial became the discriminative stimulus for reinforcement in the second component of a chained schedule. In one condition, responding was reinforced only if the number of responses in the first component was above a target value; in the other condition, responding was reinforced only if the number was below the target value. The distribution of the first-component response numbers did not shift systematically between discrimination conditions, but response rates in the second component indicated that the number of responses in the autoshaping trial was a discriminable property behavior.

Animals↗
PubMed2005

The carrot, not the stick: appetitive rather than aversive gustatory stimuli support associative olfactory learning in individually assayed Drosophila larvae.

The ability to learn is universal among animals; we investigate associative learning between odors and "tastants" in larval Drosophila melanogaster. As biologically important gustatory stimuli, like sugars, salts, or bitter substances have many behavioral functions, we investigate not only their reinforcing function, but also their response-modulating and response-releasing function. Concerning the response-releasing function, larvae are attracted by fructose and repelled by sodium chloride and quinine; also, fructose increases, but salt and quinine suppress feeding. However, none of these stimuli has a nonassociative, modulatory effect on olfactory choice behavior. Finally, only fructose but neither salt nor quinine has a reinforcing effect in associative olfactory learning. This implies that the response-releasing, response-modulating and reinforcing functions of these tastants are dissociated on the behavioral level. These results open the door to analyze how this dissociation is brought about on the cellular and molecular level; this should be facilitated by the cellular simplicity and genetic accessibility of the Drosophila larva.

Animals↗
PubMed2004

Strengthening PBL through a discursive practices approach to case-writing.

CONTEXT: In many ways the task of physicians is to listen to stories and place them within larger social contexts. Problem-based learning (PBL) can potentially reinforce such a view of the physician's work. The conventional PBL case, however, largely replicates the medical record, which in turn, is restricted in its purview to biomedical concerns. The conventional case thus encourages an approach to clinical reasoning that insufficiently recognizes (1) the cross-cultural nature of all clinical encounters, (2) the central role of narrative, and (3) the political economic influences that contribute to disease and suffering in our world. METHODS: We suggest ways to modify the traditional medical curriculum to include the learning of cross-cultural health through appropriately written problem-based learning (PBL) cases. We discuss two cases to illustrate how PBL cases can incorporate dialogue between patients and physicians, demonstrate the narrative character of the medical encounter and examine the political economic contributors to disease production. CONCLUSION: Fluency in language games other than that of biomedicine is required if students are to become more aware of the wider factors that contribute to suffering, and to be able to respond with compassion and understanding to that suffering. Our approach is a discursive practices approach to culture that emphasizes the emergent, participant-constructed qualities of social phenomena while also acknowledging large-scale social forces.

Cultural Diversity↗
PubMed2006

Discriminability and sensitivity to reinforcer magnitude in a detection task.

Three pigeons discriminated between two sample stimuli (intensities of red light). The difficulty of the discrimination was varied over four levels. At each level, the relative reinforcer magnitude for the two correct responses was varied across conditions, and the reinforcer rates were equal. Within levels, discriminability between the sample stimuli did not change systematically as reinforcer magnitude varied. Across levels, the sensitivity of behavior to changes in the reinforcer-magnitude ratio decreased as the discriminability between the sample stimuli increased. Subsequent analysis showed that this relation was limited to performance following only one of the sample stimuli, the dim red light that remained constant across all conditions. Extant behavioral models of signal detection cannot easily accommodate these results.

Animals↗
PubMedDate not supplied

Multiple reward systems and the prefrontal cortex.

Electrical stimulation of the major divisions of the prefrontal cortex, the mediodorsal and sulcal areas, can serve as a reinforcing stimulus. Studies of self-stimulation of the prefrontal cortex have produced behavioral, anatomical and pharmacological evidence that the substrate of these rewarding effects can be dissociated from that subserving self-stimulation of ventral diencephalic sites such as the lateral hypothalamus. Other studies indicate that within the prefrontal cortex itself, self-stimulation of the medial and sulcal divisions can be attributed to dissociable processes. These observations suggest the existence of multiple, largely autonomous prefrontal subsystems involved in reinforcement. This raises the question of the functional significance of such systems, and of their organization. An approach to this problem is to consider the relationship between the behavioral functions of the prefrontal divisions and the characteristics of stimulation-induced reward obtained at each site. Studies of the effects of restricted prefrontal lesions indicate that the medial and sulcal divisions can be dissociated according to their involvement in the control of distinct types of sensory and motor events. Further experiments indicate that damage to each division causes selective deficits in the learning of stimulus-reinforcer and response-reinforcer relations, depending in part on the nature of the reinforcing event. Conditioning experiments further show that the rewarding effects produced by stimulation of these areas are preferentially associated to sensory events which correspond to the functional specialization of each division. These data are interpreted to suggest that different rewarding events and/or different attributes of rewarding stimuli are processed by distinct systems which are reflected by the organization of dissociable self-stimulation pathways.

Animals↗
PubMed1965

INTERHEMISPHERIC REVERSAL OF MIRROR-IMAGE OBLIQUE LINES AFTER MONOCULAR TRAINING IN PIGEONS.

Pigeons, with one eye open, were reinforced for pecking at a 45 degrees oblique line (/). When the opposite, untrained, eye alone was open, pigeons responded maximally to the mirror-image (135 degrees [unknown]) of the training stimulus (45 degrees [unknown]). This unexpected interocular reversal of mirror-image stimuli has not been reported for any other species.

Animals↗
PubMedDate not supplied

Melioration and the transition from touch-typing training to everyday use.

Previous research shows that success in touch-typing training does not ensure its continuation into everyday use. It is postulated that an important contributor to this problem is melioration--that is, maximizing local rates of reinforcement. In the context of typing, melioration implies an intuitive tendency to choose typing strategies that lead to a better immediate performance level than that obtained by touchtyping. One such strategy is visually guided typing, in which the performer looks at the keys to locate their position. The present research describes a training approach that changes the reinforcement structure by increasing the attractiveness of looking at the screen while typing. This approach is implemented by using a secondary task that requires typists to respond to signals appearing on the screen. In an experiment that evaluated this solution, 22 students were given a touch-typing training course followed by a period in which they had to type their own homework. The results showed that under a modified reinforcement condition, the effect of melioration on touch-typing scores in the posttraining phase decreased. In addition, the experimental manipulation facilitated the acquisition and maintenance of the touch-typing skill. Actual or potential applications of this research include research in training, choice behavior, and human-computer interaction.

Adult↗
PubMed1984

Modulation of turning preferences by learning.

Rats were trained, using water reinforcement, to turn in circles (rotation) during 1 h daily test sessions. Different groups of rats were reinforced for turning either in the same or opposite direction as that elicited previously by D-amphetamine. All rats (n = 14) trained in the 'same' direction readily acquired the task whereas only 13 of 33 rats trained in the 'opposite' direction showed evidence of learning. Two days after cessation of training, the effect of D-amphetamine was greater in rats trained in the 'same' direction and decreased or reversed in rats successfully trained in the 'opposite' direction - these changes were transient, mostly disappearing a week later.

Animals↗
PubMed1985

[Behavioral approaches to communication disorders in schizophrenics].

Behavior therapy has used techniques of behavior modification based on the paradigm of operant conditioning to diminish some of the difficulties of communication present in schizophrenic patients. Individual programmes, then ward programs, have been applied to chronically institutionalized patients. They have emphasized the role of reinforcement and of social learning in behavioral approaches. More recently, these techniques have focused on the improvement of performance in social situations. As can be seen in the literature, modern behavior therapy is founded on a sociopsychological model in which environmental factors have a predominant role and focuses on maintaining behavioral improvement in the patient's day-to-day environment.

Behavior Therapy↗
PubMed1980

Undermatching on concurrent variable-interval schedules and the power law.

The phenomenon of undermatching on concurrent variable-interval schedules is shown to be derivable by transforming the individual interreinforcement intervals of each variable-interval schedule and averaging the transformed values to produce an "estimate" of the rate of reinforcement the schedules deliver. If the transformation is based on a power function with a fractional exponent, such as is found in many studies of temporal control in animals, matching response rations to the ratios of these estimated rates of reinforcement yields undermatching. If the concurrent variable-interval schedules are arranged such that the individual intervals in each schedule have a constant proportionality (a procedure found in many commonly used variable-interval schedules) the slope of the line relating logarithms of response ratios and of programmed reinforcement ratios is identical to the exponent of the power transformation applied to the individual time intervals in the variable-interval schedules. In other cases this simple relation does not hold but the degree of undermatching is greater the lower the value of the exponent of the power function. This account of undermatching predicts values similar to those typically observed.

Animals↗