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PubMed1977

An experimental analysis of peer social initiations on the behavior of withdrawn preschool children: some training and generalization effects.

In this study, positive social initiations by an age-peer was evaluated as an intervention for isolate preschool children in training and generalization sessions. During baseline, the confederate made few social approaches to the target subjects. The confederate greatly increased his rate of positive social initiations during the first intervention, decreased social approaches during a second baseline, and increased social approaches again in a second intervention phase. Increases in confederate initiations resulted in an immediate acceleration in the frequency of subjects' positive social behavior during training sessions. Additionally, for two of the three subjects, positive social behaviors were also observed to increase during generalization sessions. The results suggest that (a) peers may be trained successfully to set the occasion for positive social behaviors by withdrawn classmates, (b) increased social responding by withdrawn children in the presence of frequent peer social initiations may also generalize beyond the training setting, and (c) the magnitude of direct and generalization effects appears to be related to the entry-level repertoire of target children.

Behavior Therapy↗
PubMed1986

The effect of stress on the linguistic generalization of bilingual individuals.

Spanish-English coordinate bilinguals were subjects in a GSR linguistic conditioning experiment using strong and mild buzzer conditions and spoken stimuli. Each subject was randomly assigned to one of two lists of words and one of two levels of buzzer sounds. A Spanish word from the Spanish list and an English word from the English list functioned as a conditioned word (CS). The lists were Spanish and English words related semantically and phonemically and unrelated to the CS. Generalization was studied under conscious and unconscious conditions. We found that both buzzer conditions resulted in significantly greater GSR responses to semantic and phonemic words than to words unrelated to the CS. Generalization to semantic words was not significantly greater than to phonemic words. There was a tendency toward greater phonemic than semantic generalization in the strong buzzer condition. The opposite was observed regarding the mild buzzer. The results were the same in both lists and languages. Under a conscious and unstressful condition, generalization to semantic words was found to be more prominent than to phonemic words. This suggests that under normal condition semantic generalization is mediated by conscious cognition. We concluded that strong emotion produces an increase in phonemic, as compared to semantic, generalization in both languages. Hence, primitivization of the subjects' cognitive and linguistic functioning is assumed to have occurred. These results are important in understanding the deleterious effect that stressful situations may have on linguistic functioning and cognition in bilinguals.

Adolescent↗
PubMedDate not supplied

Capacity of bottle-nosed dolphins for generalization based on a relative sign.

Using a new modification of a previously proposed method in the bottle-nosed dolphin, a conditioned reflex was developed and consolidated to a relative spatial sign, namely the choice always of the left out of two identical objects under conditions of constant change of the position of this pair of stimuli against the background of one of the sides of the pen. The specialization was checked by means of the presentation of the pair of stimuli through various changes of the surrounding setting, including the discordance of external landmarks, as well as by the means of the presentation of the stimuli. Then the objects were replaced by others (12 pairs of stimuli) sharply differing from the initial stimuli in form, size, material, etc. The maintenance of appropriate choice, including with change in the medium of presentation of the stimuli) attested to the capacity of the dolphins to abstract and generalize on the basis of a relative sign, i.e., of abstraction and generalization in the "to the left-to the right in general" choice of two objects.

Animals↗
PubMedDate not supplied

The formation of a complex skill in Black Sea dolphins under free choice conditions.

A free choice situation, characterized by the fact that any sequence of actions of dolphins on manipulators set up in a pen was reinforced, providing that they pressed on three specific levers in a required order, independent of the number of "superfluous" reactions before and between the required actions, was created in the experiment. No sequence of actions leading to reinforcement was formed in the dolphin in the first series of experiments using eight above-water levers. In the second series, using eight under-water manipulators, both experimental dolphins regularly acquired reinforcement. Stereotypical trajectories of movements about the pen, which included swimming passed the levers and sequential actions on them, were formed in these dolphins. The formation of a minimal chain of motoric reactions did not take place, although presses on some of the "superfluous" levers did stop. During the accomplishment of the task, the phenomenon of efferent generalization was manifested in two ways in the dolphins in both series of experiments: the animals acted in different ways on the very same manipulator and performed presses on various levers.

Acoustic Stimulation↗
PubMedDate not supplied

The functional role of an increase in cell excitability and synaptic efficiency in the new cortex during learning.

Data were obtained in experiments on nonimmobilized and nonanesthetized rabbits, during the development of an analog of a CR, with recording of the response of the pyramidal tract, suggesting temporal specificity in the manifestations of membrane and synaptic plasticity, the participation of these mechanisms in both representations of the combined stimuli, and primarily unidirectional changes in the degree of their participation in these points of the cortex. It is concluded that temporary membrane plasticity creates conditions through the mechanisms of synchronization and summation for the passage of excitation from the sensory link to the motor output of the new connection. The gradual reorganization of excitatory and inhibitory connections to the output elements of the conditioned reflex act, determined by the mechanisms of synaptic plasticity, determine and strengthen the specialized character of the developed reaction.

Animals↗
PubMedDate not supplied

The neuropharmacological restoration of cognitive functions of cats following a lesion to the basal nuclei of the forebrain (Meynert's nucleus).

The functions of generalization and abstraction in an experimental model of Alzheimer's disease (the lesion of Meynert's nuclei in cats) were studied against the background of stimulation and inhibition of the cholinergic, GABAergic, and dopaminergic systems of the brain. It was demonstrated that the cholinergic system is a key system for the formation of the function of generalization, the dopaminergic system improves simple forms of learning, while the GABAergic system is actively involved in the establishment of complex types of associations.

Acetylcholine↗
PubMed1994

Drug discrimination is a continuous rather than a quantal process following training on a VI-TO schedule of reinforcement.

Debate continues as to whether drug discrimination in animals is an inherently quantal or continuous process. This issue is important in determining the appropriate interpretation of results from drug discrimination studies designed to assess the nature of drug-induced interoceptive cues. The quantal approach holds that subjects perceive a drug cue in an all-or-none manner, while the continuous view proposes that when appropriate training and testing procedures are used, subjects can discriminate along a continuum of interoceptive cues. Data consistent with the quantal view have consistently been generated by animals trained to respond on schedules of reinforcement having an FR component. Since quantal responding is a characteristic of these schedules, results from drug discrimination studies using training schedules with FR components are of little value in empirically determining whether drug discrimination reflects a quantal or continuous process. Use of variable schedules of reinforcement might be more appropriate because the pattern of responding generated does not preclude results consistent with either of the competing views. Data from the following studies that trained subjects using VI schedules with a concurrent TO for incorrect lever responding were analyzed: Barrett et al. (1982): L-5-hydroxytryptophan versus saline; Smith (1990): diazepam versus pentylenetetrazol; Barrett et al. (1992): amphetamine versus haloperidol; Barrett and Steranka (1983): amphetamine versus haloperidol. In every case, when experimental conditions produced a group mean intermediate to that for the training drugs, the distribution of scores for individual animals was normally rather than bimodally distributed.

5-Hydroxytryptophan↗
PubMedDate not supplied

Disturbances in cognitive activity and its neuropharmacological correction in structural-functional insufficiency of the head of the caudate nucleus in cats.

The participation of the head of the caudate nucleus in the organization of praxis, perception, gnosis, and "ideational operations" has been demonstrated. The broad spectrum of dysfunctions observed in the presence of caudate insufficiency was eliminated by a specific set of psychotropic preparations acting on classical neuromediator systems of the brain of cats.

Animals↗
PubMedDate not supplied

Locus of semantic generalization of the galvanic skin response and possible inhibitory influence of conditional stimuli upon unconditional response following conditioning with innocuous and noxious unconditional stimuli.

Two different problems were investigated using the GSR index of the orienting reflex (OR): 1) the locus of semantic generalization; and 2) a possible inhibitory influence of the CS upon the UCR. Two experiments were conducted. One experiment employed an innocuous USC, and a second similar experiment used a loud noise as the UCS. Unidirectional word associates were employed in the test of the direction of semantic generalization. Constant and varying CS words were used to test the possible inhibitory influence of the CS upon the UCR. Evidence was obtained of semantic generalization occurring in the training and in the test situation. There was no evidence of the CS developing inhibition over the UCR. Theoretical interpretation of both phenomena were considered. The need for developing theories of conditioning of the OR in humans was emphasized in contrast to current efforts to apply inappropriate cognitive animals learning theories which fail to consider biologic constraints.

Adult↗
PubMed2002

Relation between discriminative and reinforcing effects of midazolam, pentobarbital, chlordiazepoxide, zolpidem, and imidazenil in baboons.

RATIONALE: If a psychoactive drug shares discriminative effects with one that maintains self-administration, it is often inferred that the test drug is likely to be self-administered and to have abuse liability. This presumed predictive relationship has not been studied directly, however. OBJECTIVE: To determine at the level of the individual subject (1) whether a novel drug dose that shares discriminative effects with a reinforcing drug dose also will serve as a reinforcer, and (2) whether the results of generalization tests for drugs pharmacologically similar to the training drug predict whether the test drugs will or will not be self-administered. METHODS: Baboons were trained to discriminate midazolam (0.32 mg/kg, IV) from saline and also under a schedule of IV drug reinforcement. At the beginning of a period of self-administration, the first self-injection was followed 10 min later by a drug discrimination test session. The baboon then had the opportunity to self-administer the same dose 24 h/day (3-h timeout after each injection). A second drug discrimination test followed the last self-injection of the condition. RESULTS: Zolpidem and imidazenil shared discriminative effects with midazolam. Zolpidem was reinforcing in all baboons, but imidazenil was not. Chlordiazepoxide partially shared discriminative effects with midazolam, and the rate of self-administration was low. Pentobarbital did not share discriminative effects with midazolam, but was reinforcing. For all drugs, some doses did not share discriminative effects with midazolam but were reinforcing. Generalization gradients from tests after the last self-injection were similar to those after the first self-injection. CONCLUSIONS: The discriminative effect of a drug in relation to a training drug of the same pharmacological class is not isomorphic with its reinforcing effectiveness.

Animals↗
PubMed2000

Associative and non-associative fentanyl tolerance in the rat: evaluation of cross tolerance with mu-and kappa-specific opioids.

RATIONALE: Associative tolerance to the analgesic effects of morphine is most pronounced when morphine is paired with a distinctive context at a long interdose interval (IDI). In contrast, morphine administered at a short IDI promotes the development of non-associative tolerance and disrupts the acquisition of associative tolerance. The impact of IDI on the development of associative tolerance to opioids other than morphine has not been investigated previously. OBJECTIVES: This research examined associative and non-associative tolerance to the analgesic effects of fentanyl in rats. Cross tolerance for these two forms of tolerance with morphine (mureceptor agonist) and U50,488H (kappa-receptor agonist) analgesia was also investigated. METHODS: Animals were given eight fentanyl injections (0.10 mg/kg) paired or unpaired with a distinctive context at either a 3-h (short) or 96-h (long) IDI. Subjects were then tested for tolerance in the distinctive context using the tail-flick procedure and dose-response curve methodology. RESULTS: At the short IDI, animals developed non-associative tolerance to fentanyl that was receptor specific, i.e., cross tolerant with morphine analgesia but not with U50,488H analgesia. At the long IDI, fentanyl-tested animals displayed tolerance that appeared to be controlled primarily by associative processes. This associative form of tolerance was also receptor specific, displaying cross tolerance with morphine but not with U50,488H. CONCLUSIONS: The impact of IDI on the development of non-associative and associative fentanyl tolerance is consistent with findings obtained with morphine showing that conditions conducive to the development of non-associative tolerance disrupt the acquisition of associative tolerance. The cross-tolerance data, however, did not parallel previous research examining the cross-tolerance profiles of associative and non-associative morphine tolerance.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1997

Inbred strain differences in prepulse inhibition of the mouse startle response.

Prepulse inhibition is the phenomenon in which a weak prepulse stimulus suppresses the response to a startling stimulus. Patients with schizophrenia have impaired prepulse inhibition which is thought to reflect dysfunctional sensorimotor gating mechanisms. To investigate the potential genetic basis for differences in sensorimotor gating, the responses of 13 inbred strains of mice were evaluated using the prepulse inhibition paradigm. Ten male mice from A/J, AKR/J, BALB/cByJ, BUB/BnJ, C3H/HeJ, C57BL/6J, C57BL/10J, DBA/2J, FVB/NJ, ST/bJ, 129/J, 129/SvJ, 129/SvEvTac inbred strains were tested for acoustic prepulse inhibition of acoustic and tactile startle responses. There was a wide range of responses among the inbred strains of mice. Exact strain distributions were determined for each combination of prepulse sound level and startle stimulus. In general, mice from the 129/SvEvTac, AKR/J, 129/J, and 129/SvJ strains displayed high levels of prepulse inhibition of both the acoustic and tactile startle responses. C57BL/6J, C57BL/10J and BUB/BnJ mice showed low levels of prepulse inhibition. There was also a wide range in the amplitude of the acoustic and tactile startle responses. C57BL/10J and FVB/NJ mice displayed the greatest startle responses and DBA/2J, 129/J and 129/SvJ had the poorest startle responses. There was no correlation between the level of prepulse inhibition and the amplitude of the startle response. These findings indicate that inbred strains of mice may be a useful tool to study the genetic basis of sensorimotor gating.

Acoustic Stimulation↗
PubMed2002

Hemispheric asymmetry in visual discrimination and memory: ERP evidence for the spatial frequency hypothesis.

Event related potentials (ERPs) were recorded during delayed discrimination of simple spatial frequency gratings in the high and low frequency bands. Analyses of the waveforms N170, P220, N310, P400, and slow wave (SW) indicated significant and regionally specific interaction of spatial frequency and hemisphere for N170 amplitude. This interaction was independent of memory conditions, and appeared to be in the opposite direction of what is predicted by the spatial frequency model of hemispheric asymmetry. Additional interactions between spatial frequency and hemisphere were observed for N310 in the encoding process (reference stimulus) and for SW in the retrieval process (test stimulus). The general hypothesis of an interaction of spatial frequency and hemisphere in visual cognition is supported, but the findings indicate caution in interpreting an increase in physiological measures as an indication of more efficient brain processing. Moreover, several stages of information processing may contribute to the asymmetry observed in behavioral studies, and hemispheric balance may change dynamically during the time course of processing.

Adult↗