SEARCH · Search PubMed

Results for “Generalization, Stimulus”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46Linked to original sources

PubMed2002

Stability of functional equivalence and stimulus equivalence: effects of baseline reversals.

Functional equivalence and stimulus equivalence classes were established, reversed, and tested for stability with college students. Functional stimulus classes were established using a task in which students were trained to say nonsense words in the presence of arbitrarily assigned sets of symbols. Computer-controlled speech-recognition technology was used to record and analyze students' vocal responses for accuracy. After the establishment of stimulus classes was demonstrated with a transfer-of-function test, the effects of reversing selected baseline simple discriminations were assessed during an additional transfer-of-function test and a follow-up test that occurred several weeks later. With the same students, stimulus equivalence classes were established and demonstrated with computerized matching-to-sample procedures. The effects of reversing selected baseline conditional discriminations also were assessed during a postreversal equivalence test and a follow-up test. Both functional stimulus classes and stimulus equivalence were sensitive to contingency reversals, but the reversals with stimulus equivalence closses affected stimulus class organization whereas reversals with functional stimulus classes did not. Follow-up performances were largely consistent with the original baseline contingencies. The similarities and differences between stimulus equivalence and functional equivalence are related to the specific contingencies that select responding in the presence of the stimuli that form the classes.

Adolescent↗

PubMedDate not supplied

Discriminative stimulus effect of phenylephrine.

Rats were trained to discriminate phenylephrine in a two-lever, food-motivated operant task by increasing the i.p. administered training dose from 0.8 to 2 mg/kg. Stable discrimination to 2 mg/kg phenylephrine was established and testing of 0.5-2.5 mg/kg was shown to be dose-responsive and allowed for a calculated ED50 value of 0.87 mg/kg. Administration of methoxamine (0.5-6 mg/kg), another alpha 1-adrenoceptor agonist, produced a dose-responsive generalization, whereas only the lowest (0.04 mg/kg) and highest (0.12 mg/kg) doses of the alpha 2-adrenoceptor agonist clonidine produced generalization in the phenylephrine-trained rats. Likewise, yohimbine (2.5-4.5 mg/kg) generalized, whereas pretreatment with prazosin (0.1-0.4 mg/kg), the alpha 1-adrenoceptor antagonist, dose-responsively decreased phenylephrine discrimination. The results would indicate that phenylephrine is capable of controlling differential responding in a drug discrimination paradigm and would suggest that this effect is centrally mediated. The possibility that peripheral administration of phenylephrine (Neosynephrine) affects the brain in chronic users of nasal decongestants is discussed.

Adrenergic alpha-Agonists↗

PubMed1989

The discriminative stimulus properties of the 5HT1 agonist RU24969.

Using standard operant procedures, rats were trained to discriminate the 5-HT agonist RU24969 (0.5 mg/kg IP) from saline. Stable responding was established and tests of stimulus generalisation and stimulus antagonism were performed with a range of 5-HT receptor ligands. The RU24969 cue was selective as neither 5-HT receptor ligands MK212, DPAT, ipsapirone, GR38032F or the 5-HT releasing agent, fenfluramine nor yohimbine were able to substitute for RU24969 in tests of generalisation. However, TFMPP, CPP and, of particular interest, propranolol substituted for the RU24969 stimulus, although full substitution only occurred with doses that disrupted responding. The RU24969 stimulus was not antagonised by propranolol, metergoline, ritanserin or GR38032F. This pharmacological profile suggests that the RU24969 stimulus is mediated via a subtype of 5-HT1 sites different from 5-HT1A and that propranolol may be an agonist at this site.

Animals↗

PubMed1995

The time-dependent stimulus effects of R(-)-2,5-dimethoxy-4-methamphetamine (DOM): implications for drug-induced stimulus control as a method for the study of hallucinogenic agents.

The pharmacodynamic characteristics of the stimulus effects of the hallucinogens d-LSD and (-)DOM were investigated in the rat. The stimulus control induced by (-)DOM (0.56 mg/kg) was significantly less stable at the 15-min pretreatment time than at the 75-min pretreatment time. In addition, (-)DOM (0.8 mg/kg) produced a time-dependent substitution for the LSD stimulus in LSD trained subjects (0.1 mg/kg, 15-min pretreatment time). As pretreatment times were increased, the substitution of (-)DOM (0.8 mg/kg) for the LSD stimulus increased, culminating in a maximal level of 99.5% LSD-appropriate responding at the 75-min pre-treatment time. A dose-response relationship for the substitution of (-)DOM (75-min pretreatment time) for the LSD stimulus, indicated that 0.2 mg/kg (-)DOM was the minimum dose which elicited greater than 90% LSD-appropriate responding. LSD (0.32 mg/kg, 15-min pretreatment time) fully substituted for (-)DOM in the (-)DOM trained subjects (0.56 mg/kg, 75-min pretreatment time). These findings suggest that the pharmacodynamic parameters of d-LSD and (-)DOM-induced stimulus control differ. The time of onset for the stimulus effects of (-)DOM is markedly longer than that of LSD in the rat.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗

PubMed1988

Effects of clozapine on fixed-consecutive-number responding in rats: a comparison to other neuroleptic drugs.

The effects of clozapine and several other neuroleptic drugs were examined in rats responding under fixed-consecutive-number (FCN) schedules with minimum response requirements of 4 and 8. Under these schedules, rats were trained to respond either 8 or more times or 4 or more times on one lever, and then respond once on a second lever. In one component of these schedules, an external discriminative stimulus was presented following the completion of the response requirement on the first lever, whereas no stimulus change was programmed under the other. Under the FCN 8 schedule without the external discriminative stimulus, clozapine produced large dose-dependent decreases in accuracy (percent of reinforced response runs), whereas molindone produced small decreases in accuracy. Neither clozapine or molindone, however, altered accuracy under the FCN 4 without the external discriminative stimulus. Under these same schedules, loxapine, chlorpromazine, haloperidol and thioridazine produced small increases in accuracy at intermediate doses without affecting accuracy at the low and high doses. None of the neuroleptics evaluated produced accuracy-altering effects under the FCN schedules with the external discriminative stimulus. In general, all of these drugs decreased response rates in a dose-dependent fashion. The order of potency for the rate-decreasing effects of these drugs was loxapine greater than haloperidol greater than molindone greater than clozapine = chlorpromazine greater than thioridazine. Thus, the effects of clozapine on accuracy under the FCN schedules without the external discriminative stimulus differed qualitatively from those of other neuroleptic agents.

Animals↗

PubMed1985

Drug discrimination studies.

Opioid agonists and agonist/antagonists comprise a heterogeneous body of compounds that can be partitioned into at least three groups on the basis of their discriminative stimulus properties in several animal species: (1) stimulus effects similar to those of morphine or fentanyl and blocked completely by low doses of antagonists, such as naloxone and naltrexone; (2) stimulus effects similar to those of ethylketocyclazocine or nalorphine and blocked by higher doses of antagonists; (3) stimulus effects similar to those N-allylnormetazocine or phencyclidine and not blocked by antagonists. This diversity of stimulus properties is consistent with other evidence that multiple populations of receptors mediate the actions of opioids. In man, drugs in group 1 produce subjective effects that are entirely morphine-like and highly reinforcing whereas drugs in groups 2 and 3 produce dysphoric and psychotomimetic subjective effects. Thus, discriminative stimulus properties of opioids appear to reflect drug actions at the neuronal level that are directly relevant to potential for abuse in man.

Analgesics, Opioid↗

PubMed1972

The influence of ultraviolet radiation on the pigeon's color discrimination.

Two experiments demonstrated the pigeon's sensitivity to ultraviolet light. In Experiment I, pigeons' responses were reinforced on a multiple schedule with a variable-interval reinforcement schedule in one component and extinction in the other component. Response rates were quite different in the two components where the 520-nm stimuli signalling each component differed only in that one of them contained a 366-nm ultraviolet component. In Experiment II, pigeons were trained to peck one side key when two halves of a split field were of different wavelength and to peck another side key when they were of the same wavelength. Initially, field halves contained both "visible" and ultraviolet components of energy. Discrimination performance improved when the ultraviolet component was removed from one field half. It was argued that the critical change in the stimulus was a color change, rather than a brightness one, or a fluorescence of structures in the pigeon's eye.

Animals↗

PubMed1984

Stimulus properties of clonidine in chronically morphine treated rats trained to a morphine-saline discrimination.

In an operant behavior procedure of lever pressing on an FR 10 schedule of food reinforcement, morphine dependent and nondependent rats were trained to respond on a lever on one side of the food tray after a morphine (10 mg/kg i.p.) injection and to respond on a lever on the alternate side after a saline injection. Following discrimination training, in both dependent and nondependent rats saline was generalized to various doses of clonidine (10, 30 and 50 micrograms/kg i.p.). A response inhibition of about 65% was obtained with the highest dose. It was concluded that, even if clonidine can suppress signs of narcotic withdrawal, the internal state induced by morphine in an abstinent rat does differ from the one induced by clonidine in the same animal.

Animals↗

PubMed1973

On the development of stimulus control.

Pigeons were trained to peck one key when presented with white noise at any of five intensities lower than a reference intensity, and to peck another key when presented with white noise at any of five intensities greater than the reference intensity. The shape of the stimulus control curves (proportion of responses to one key versus stimulus intensity) changed from a horizontal line at the beginning of training to the sigmoid form of typical psychometric functions at the end of training. The development of stimulus control is described in terms of a model based on the theory of signal recognition and a concept of attention.

Acoustic Stimulation↗

PubMedDate not supplied

Noisy spiking neurons and networks: useful approximations for firing probabilities and global behavior.

Electrophysiological properties of spiking neurons receiving complex stimuli perturbed by noise are investigated. A semi-analytical estimate of firing probabilities and subthreshold behavior of the stochastic system can be made in terms of the solution of a purely deterministic system. The method comes from an approximation for the distribution function and moments of the underlying non linear multidimensional diffusion process. This so called moment method works for general conductance-based systems and an application is presented for the Hodgkin-Huxley neuronal model. Statistical properties obtained from the moment method are compared with direct numerical integration of the stochastic system. The firing probability due to external noise is derived as a closed formula. Results are given for different forms of the deterministic component of the stimulus. A generalization to neural networks of conductance-based systems with internal currents perturbed by noise can be obtained using the same approach. In the case of fully connected networks, a mean field population equation is derived which may be compared to Kuramoto's master equation for weakly coupled neural oscillators.

Action Potentials↗

PubMed1994

The relations of emotionality and regulation to dispositional and situational empathy-related responding.

The purpose of the present study was to examine the prediction of adults' situational and dispositional empathy-related responses from measures of emotionality (emotional intensity and positive and negative affect) and regulation. A multimethod approach including self-reported, facial, and heart rate (HR) responses was used to assess situational vicarious emotional responding; Ss' (and sometimes friends') reports were used to assess the dispositional characteristics. In general, dispositional sympathy, personal distress, and perspective taking exhibited different, conceptually logical patterns of association with indexes of emotionality and regulation. The relations of situational measures of vicarious emotional responding to dispositional emotionality and regulation varied somewhat by type of measure and gender. Findings for facial and HR (for men) measures were primarily for the more evocative empathy-inducing stimulus. In general, the findings provided support for the role of individual differences in emotionality and regulation in empathy-related responding.

Adolescent↗

PubMed1999

Value of the initial stimulus dose in right unilateral and bifrontal electroconvulsive therapy.

BACKGROUND: The outcome of electroconvulsive therapy (ECT) is affected by the placement and dose of the stimulus. In general, the ECT dose can be selected either by the dose-titration method (on which the measured seizure threshold level is based), or the method of predetermined dose (e.g. the age-based dosing and the fixed high dose method). METHODS: Seizure thresholds were measured in 50 patients with right unilateral (RUL) and in 30 patients with experimental bifrontal (BF) ECT stimulus. The ECT dose (mC) of the age-based dosing was calculated by multiplying the age (years) by 5.0 (age method) or 2.5 (half-age method). The fixed high dose was set to 378 mC. RESULTS: The seizure thresholds had only a moderate correlation with the age of the patients. The methods based on the predetermined dose would have led us to give patients with the lowest seizure thresholds in the RUL ECT group very high stimulus doses, up to 12 (age method) or 15 (fixed high dose method) times the individual seizure threshold. In contrast, the RUL ECT patients with the highest seizure thresholds would have received low stimulus doses down to 1.5 times (half-age method) the initial seizure threshold. In the BF ECT group the-age based dose would have been similarly dependent on the initial seizure threshold level. CONCLUSION: The use of the dose-titration method is recommended, because it is the only method that allows for the individual selection of ECT stimulus dose relative to the seizure threshold.

Adult↗

PubMed1986

(+)-3-PPP antagonizes the discriminative stimulus effects of (+)-N-allylnormetazocine.

The functional significance of the reported affinity of (+)-3-PPP and (+)-N-allylnormetazocine (NANM) for the same binding site in rat brain membranes was assessed by studying (+)-3-PPP as a agonist and antagonist of (+)-NANM in rats trained to discriminate 5.0 mg/kg (+)-NANM from saline. Over a wide dose range, (+)-3-PPP was able to block the discriminative stimulus effects of (+)-NANM, with complete antagonism at 1.0 mg/kg i.p. Since (+)-NANM is a prototype sigma-opioid agonist, (+)-3-PPP is a good candidate for being a competitive sigma antagonist.

Animals↗

PubMed2002

Acquired equivalence and distinctiveness of cues: II. Neural manipulations and their implications.

Neural manipulations were used to examine the mechanisms that underlie the acquired equivalence and distinctiveness of cues in rats. Control rats and those with excitotoxic lesions of either the hippocampus (HPC) or entorhinal cortex (EC) acquired the following conditional discrimination: In Contexts A and B, Stimulus X-->food and Stimulus Y-->no food, and in Contexts C and D, Y-->food and X-->no food. Rats then received many food pellets in A but not in C. After this treatment, control rats showed more magazine activity in B than in D--an acquired equivalence-distinctiveness effect. This effect was also evident in HPC rats but not in EC rats. These results indicate that changes in stimulus distinctiveness are dissociable from the process of conditional learning.

Analysis of Variance↗

PubMed1994

Matching to complex samples and stimulus class formation in adults with autism and young children.

Adults with autism and young children first learned to match one-element comparison stimuli to two-element sample stimuli. Test conditions then examined whether each of the individual sample elements (a) controlled selections of the comparison stimuli to which they were related during training, (b) were interchangeable with one another as either sample or comparison stimuli, and (c) were interchangeable with the original comparison stimuli. Test data were positive and suggested the formation of three-member stimulus classes. Subsequent experiments demonstrated the formation of four-member classes by (a) adding novel stimuli by training outside the original context; (b) adding novel stimulus elements to the two-element samples used during baseline training; and (c) training with three-element rather than two-element sample stimuli from the outset. Results suggest that acquisition of stimulus classes may be one of the benefits of broad rather than restricted attention to the components of complex stimuli.

Adult↗

PubMed2003

Changes in stimulus salience as a result of stimulus preexposure: evidence from aversive and appetitive testing procedures.

In two experiments, rats received preexposure to three compound flavor stimuli, AX, BX, and CX, where X represents a saline solution. AX and BX were presented in alternation; CX, on a separate block of trials. The value of X was then modified, being devalued by aversive conditioning in Experiment 1, and rendered valuable by the induction of a state of salt need in Experiment 2. When given a choice between BX and CX, the rats consumed more of BX than of CX in Experiment 1, and more of CX than of BX in Experiment 2, suggesting that B and C differed in their ability to modulate the response governed by the X element. It was suggested that blocked preexposure to CX reduces the salience of the C stimulus but that the salience of B is maintained by preexposure in which BX is alternated with AX. The implications of this result for the phenomenon of perceptual learning are discussed.

Animals↗

PubMed1976

Effects of a stimulus associated with a victim's pain on later aggression.

Male college students participated in an experiment designed to associate a neutral stimulus with a victim's pain and then to assess the impact of the paired stimulus on their aggression. The subjects were either provoked or not provoked by a confederate's shock evaluation. They then observed a flashing white light that was associated with either their former evaluator's pain or an irrelevant, affectively neutral event. The subjects then administered electric shocks to a different confederate, with whom they had not interacted previously, at the flash of both the familiar white light (the conditioned stimulus) and a novel blue light. Results supported the prediction that provoked subjects would give more intense shocks to the conditioned stimulus when it had been associated with their evaluator's pain. Unprovoked subjects were found to give less intense shocks to the light that had been associated with their evaluator's pain.

Aggression↗

PubMed1998

Discriminative stimulus properties of nicotine at low doses: the effects of caffeine preload.

Discriminative stimulus properties of low nicotine doses administered in the form of chewing gum in combination with caffeine have been evaluated in humans, using established behavioural drug discrimination procedures. Twenty-one smokers who were also regular coffee drinkers were trained to discriminate 0 versus 1 mg nicotine chewing gum. Twenty subjects (11 men and nine women) were able to reach criterion performance (at least 80% correct). Generalization of responding across nicotine doses of 0, 0.25, 0.5 and 1 mg was then examined. Subjects were randomly allocated to receive either 50 mg caffeine or placebo before testing. Nicotine-appropriate responding was linearly related to dose, demonstrating that smokers can accurately discriminate nicotine from placebo and between relatively small doses of nicotine. Nicotine-appropriate responding was high at the 0 mg nicotine dose in the caffeine group demonstrating a partial generalization. Subjective effects assessed concurrently with behavioural discrimination revealed that nicotine discrimination was guided by the interoceptive cues of 'sensations in mouth', 'taste', 'heart rate', 'stimulated', 'alert' 'jittery' and 'nausea'. Caffeine increased self-ratings of 'stimulated' and 'alert' (at the 0 mg nicotine dose) and 'jittery' at the 0.5 and 1.0 mg nicotine dose. Relationships between nicotine-appropriate responding and subjective feelings induced by caffeine suggested that feelings of 'stimulated' and 'alert' were guiding discrimination behaviour. These data are discussed in terms of interoceptive nicotine cues and their importance at different doses and after caffeine preload.

Adult↗