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Results for “Conditioning, Operant”

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PubMed2001

Disordered eating behaviors and reward sensitivity.

This research evaluated the extent to which reward sensitivity demonstrated associations with binge and purge behavior frequency. A verbal operant conditioning task designed to assess conditionability to reward cues was administered to a sample of 34 women who exhibited disordered eating patterns for at least I month prior to study participation. Reward sensitivity significantly correlated with the average weekly frequency of purge (r = 0.44) but not binge behaviors. These findings suggest that reward sensitivity has some associations with aspects of disordered eating and therefore may have relevance for theories on the maintenance of some forms of eating disorder-related behavior.

Adolescent↗

PubMed2000

Impaired two-tone processing at rapid rates in male rats with induced microgyria.

We previously reported that adult male rats with bilateral induced microgyria exhibit deficits in rapid auditory processing, which appear similar to auditory processing deficits seen in individuals with developmental language disabilities. The current study was designed to further elaborate that finding using an improved paradigm in which stimulus duration was uncoupled from testing experience and learning effects. Specifically, two-tone stimuli with durations of 540, 390, 332 and 249 ms were all presented within a single test session in a modified operant conditioning paradigm. Subjects were tested over a period of 12 days using this variable-stimulus format. Results confirmed microgyric male rats were impaired only in processing two-tone stimuli presented at rapid rates (i.e., 249 ms duration). Thus the current results support the previously observed link between focal malformations and deficits in rapid auditory processing.

Acoustic Stimulation↗

PubMed2000

When does inter-hemispheric integration of visual events emerge in infancy? A developmental study on 19- to 28-month-old infants.

Simultaneous attention in the two visual fields and interhemispheric integration of visual information was studied in 19-23 and 24-28-month-old infants. The stimuli were schematic faces within which the pair of eyes was made of either two identical (two circles or two triangles) or two different eyes (triangle-circle, circle-triangle). The faces were presented either in one visual hemifield, on the right or left side of a central fixation point (unilateral presentation), or across the two visual hemifields (bilateral presentation), with one eye of the stimulus on each side of the fixation point. The task was an operant conditioning task where the children had to decide whether the shapes of the two eyes were identical or not. The results show that even the younger subjects were able to perform the task when presented in the unilateral presentation condition, whereas only children aged 24 months and older could learn the task when presented in the bilateral condition. It is concluded that simultaneous attention to the two visual fields and inter-hemispheric co-ordination of visual information emerge very late in development at about the age of 24 months.

Age Factors↗

PubMed2001

Persistent suppression of ethanol self-administration by brief social stress in rats and increased startle response as index of withdrawal.

Excessive alcohol drinking is often linked to the experience of stress, but experimental approaches using animal models of alcohol self-administration have had widely varying outcomes. The objective was to determine how daily exposure to brief, predictable social stress would change alcohol self-administration in rats in a daily limited access protocol. Male Long-Evans rats had either access to a 10% ethanol solution for 15 min in the home cage setting (n=20) or were reinforced with 15% ethanol deliveries for every fifth lever press (n=10). Subsequently, all rats were subjected to brief social stress for five consecutive days. Social stress consisted of attacks by an opponent for 5 min followed by exposure to threats while in a protective cage for 30 min. In both the home cage drinking and operant conditioning groups, social stress exposure significantly decreased alcohol intake or rate of alcohol reinforcements, respectively. When alcohol intake was scheduled immediately before social stress (i.e., 24 h after the previous social stress episode), a decrease was observed with a delay of 1 or 2 days. When alcohol intake was scheduled 4 h after stress, no changes in intake or alcohol reinforcements were observed. Animals that consumed a low dose of ethanol displayed less defensive behavior during social stress compared to water-drinking animals, and showed an increased startle reflex at 8 and 56 h after discontinuation of daily ethanol access. The current experimental protocols of social defeat stress reveal a transient suppression rather than a facilitation of alcohol consumption.

Aggression↗

PubMed2003

Successful acquisition of an olfactory discrimination paradigm by spider monkeys, Ateles geoffroyi.

The present study demonstrates that an operant conditioning paradigm-originally designed for assessing olfactory performance in an Old World primate, the pigtail macaque-can successfully be adapted for use with a New World primate, the spider monkey. Using a task based on a food-rewarded, two-choice discrimination of simultaneously presented odor stimuli, Ateles geoffroyi is capable of learning to discriminate between objects on the basis of odor cues. Moreover, animals could readily transfer to new S+ and S- stimuli, and could remember the significance of previously learned odor stimuli even after a 4-week break. We could also show that this method is suitable for obtaining reliable measures of olfactory sensitivity. Our results indicate that A. geoffroyi clearly outperforms Macaca nemestrina with regard to the speed of initial task acquisition and the ability to master transfer tasks, and shows a sensitivity to a food-related odorant which matches that of other primate species.

Animal Feed↗

PubMed1997

Daily rhythms in a complex operant: targeted percentile shaping of run lengths in rats.

Daily rhythms in response output and accuracy were examined when reinforcement for a complex operant was uncoupled from accuracy of performance. Rats housed in operant conditioning chambers earned their daily ration of food under a targeted percentile procedure for responding on two levers. The targeted pattern was a series of consecutive responses on the left lever (a "run"), followed by a single response on the right lever. The targeted run length was either "O" (i.e., undefined, under the nondifferential baseline), 6, 12 or 24. Under baseline, a random third of all trials ended in pellet delivery; under the percentile conditions, trials with runs closer to the target than two-thirds of the runs from the most recent 24 trials ended in pellet delivery. This contingency shaped run lengths while ensuring that approximately one-third of all trials produced pellets. Responding tracked the target value well, with mean obtained run lengths equal to 90% of the target or better. Daily rhythms were clearly evident in measures of overall output, with subjects responding primarily 3-7 h into the dark period. The only substantial light-period responding observed in all subjects occurred during the 2 h after noon, when the chambers were serviced. No systematic variation in this pattern was observed as a function of target. Run length was much less variable across the daily cycle than was response output, with only a suggestion under the longest target that response accuracy was lower during periods removed from the period of peak activity.

Animals↗

PubMed2000

Visual perception and stimulus orientation in cattle.

The pupil in the eye of adult cattle is oval under contraction with the long axis nearly horizontal. Based on simple optophysical facts it is hypothesised that visual perception in such eyes is different for stimuli with vertically-separated details rather than stimuli with horizontally-separated details. This hypothesis was tested with three adult dairy bulls using an operant conditioning technique. The bulls had to discriminate a solid white line from broken white lines with decreasing interspaces. They solved this task better when the stimuli were presented vertically rather than horizontally. This result is discussed in terms of visual acuity and related to the topographical anatomy of the eye, particularly the pupil.

Animals↗

PubMed2002

Measuring and modelling the photopic flicker sensitivity of the chicken (Gallus g. domesticus).

The photopic flicker sensitivity of the chicken was determined using an operant conditioning psychophysical technique. The results show both high- and low-frequency fall-off in the sensitivity response, which peaked around 15 Hz. Flicker sensitivity was determined for a range of stimulus luminance levels, and directly compared to human flicker response measured under similar stimulus conditions. At five luminance levels (10, 100, 200, 500 and 1000 cd/m(2)), the overall chicken flicker sensitivity was found to be considerably lower than for humans, except at high frequencies. A greater degree of frequency tuning was also found in the chicken response. The critical flicker fusion values were either similar or slightly higher for chickens compared to humans (40.8, 50.4, 53.3, 58.2 and 57.4 Hz vs 39.2, 54.0, 54.0, 57.4 and 71.5 Hz respectively for humans and chickens for increasing stimulus luminance level). A recently proposed model for flicker sensitivity [Vision Research 39 (1999) 533], which incorporates low- and high-pass temporal filters in cascade, was found to be applicable to the chicken response. From this model, deductions were made concerning mechanisms controlling the transfer of temporal information.

Adult↗

PubMed2002

A simple procedure for assessing ataxia in rats: effects of phencyclidine.

The present study describes an objective, cost- and time-efficient procedure for characterizing the ataxic effects of psychoactive drugs. Male Sprague-Dawley rats were administered an intraperitoneal injection of either saline or one of three doses (1, 5 or 10 mg/kg) of phencyclidine (PCP) 15 min prior to being placed into an empty standard operant conditioning chamber (all manipulanda were removed). The floor of the test apparatus consisted of parallel rows of metal rods spaced approximately 1.5 cm apart. During a 5-min test, a single observer counted the frequency with which each animal's paws (front or back) slipped between the rows of bars that constituted the cage floor. The data demonstrated that while saline animals exhibited no instability in their ambulation, PCP-treated animals demonstrated a highly reliable dose-dependent increase in the number of "paw slips" in a single trial. Since animals are known to develop tolerance to the ataxic response to PCP, the validity of the test as a measure of drug-induced ataxia was examined in a separate group of animals treated with the middle (5 mg/kg) dose every other day over the course of a 9-day period (i.e., resulting in five injection trials). In this experiment, each subsequent test produced a reliable reduction in the magnitude of the ataxic response, and by the fifth drug challenge, the PCP animals were performing at near-control levels. These results suggest that the "paw slip test" can serve as a simple, reliable, objective and valid measure of drug-induced ataxia. The relevance of the ataxia data for interpreting the locomotor response of animals treated with PCP is also discussed.

Animals↗

PubMed1997

Motor dysfunction produced by tacrine administration in rats.

In the present study, three experiments were conducted to provide a characterization of some of the motor effects of the anticholinesterase tacrine (1.25-5.0 mg/kg I.P.) in rats. In the first experiment, tacrine was found to produce tremulous jaw movements in the dose range of 1.25-5.0 mg/kg. The second experiment examined the effects of tacrine on locomotion, and it was demonstrated that tacrine produced a dose-related suppression of open-field motor activity. In the third experiment, the effects of tacrine were assessed using operant conditioning procedures. Behavioral output during lever pressing on a fixed ratio 5 schedule was recorded by a computerized system that measured response initiation time (time from offset of one response to onset of the next) and duration for each lever press. Tacrine administration substantially depressed lever pressing response rate. This deficit was largely due to a substantial increase in the average response initiation time. Analysis of the distribution of response initiation times indicated that tacrine-treated rats made relatively few responses with fast initiation times (e.g., 0-125 ms), and also that tacrine led to a dramatic increase in the number of pauses in responding (i.e., response initiation times greater than 2.5 s). Tacrine-treated rats showed a slight increase in the average initiation time for fast responses (i.e., a slight decrease in the local rate of responding), and also showed a substantial increase in the average length of pauses greater than 2.5 s. Analysis of response durations indicated that there was an overall increase in average response duration among animals that received the higher doses of tacrine. Although tacrine-induced decreases in the local rate of responding and increases in response duration contribute to the overall deficit, the major reason why tacrine-treated animals responded less was because they took much longer breaks in responding. It is possible that the tacrine-induced increases in pausing reflect a drug-induced akinesia. Thus, the present experiments indicate that tacrine impairs several aspects of motor function in the dose range tested. In view of the fact that tremor and motor slowing are classic symptoms of Parkinsonism, the present results in rats are consistent with the human literature indicating that tacrine (Cognex) can produce Parkinsonian side effects. Studies of the motor dysfunctions produced by tacrine in rats could be useful for investigating the motor side effects of tacrine in humans.

Animals↗

PubMed1983

Facilitation of memory consolidation by post-training electrical stimulation of the medial septal nucleus: is it mediated by changes in rhythmic slow activity?

Sinusoidal (100 Hz) electrical stimulation was applied at a weak intensity (7.5 muA peak to peak) through bipolar electrodes located in the medial septal nucleus after partial acquisition of an appetitive operant conditioning task in a Skinner box. Analysis of performance in a retention test 24 hr later showed that (i) the presence of stimulation electrodes by itself impaired retention-test performance, and (ii) electrical stimulation applied 30 sec after the end of the acquisition session improves retention; this facilitatory effect disappeared when the treatment was delayed 15 min. Both impairment and facilitation were found to vary (considerably) among subjects. Electrodes located in the center of the medial septal nucleus led to both a greater impairment in unstimulated subjects and a greater facilitation in stimulated subjects than more anterior placements in the vicinity of the diagonal band. Finally, spectral analysis of hippocampal EEG showed that stimulation had no effect on rhythmic slow activity (RSA). These results are discussed in relation to studies showing that RSA is associated with memory-storage processes and our own hypothesis which underlines the importance of activation of septo-hippocampal cholinergic neurons in the early stages of these mnemonic processes.

Animals↗

PubMed2003

Impaired DRL 30 performance during amphetamine withdrawal.

Repeated administration of psychomotor stimulants may produce an impulsive state that could contribute to the cycle of drug abstinence and relapse seen in human drug addicts. We have previously reported that the inhibitory effects of dopamine (DA) on the firing rate of medial prefrontal cortex (mPFC) neurons were reduced in rats after repeated amphetamine treatment suggesting impaired mPFC DA function. Here, we used a differential reinforcement of low rates of responding (DRL) operant conditioning task, which is dependent on mPFC DA, to test impulsivity and inhibitory control. Food-restricted rats were trained to inhibit a nose poke response for 30s before a subsequent nose poke would result in a food reward (DRL 30). Once training was completed, rats received 5 days of no treatment, daily i.p. saline injections or daily i.p. injections of 5mg/kg amphetamine. Nine days of DRL 30 test performance began following a 3-day withdrawal from treatment. The percent of training active hole nose pokes was significantly increased and the percent of training efficiency was significantly decreased in rats withdrawn from repeated amphetamine administration as compared to saline or nai;ve rats. This suggests that impulsivity is increased during amphetamine withdrawal, which we hypothesize is associated with disrupted DA function in the mPFC.

Animals↗

PubMed1997

Strategies for harmonic structure discrimination by zebra finches.

We trained zebra finches on a go/no-go operant conditioning procedure to discriminate between two harmonic structures that differed only by the presence or absence of the second harmonic. Test sessions revealed that the birds responded to probe stimuli based on the presence or absence of the second harmonic regardless of the other frequency components. Some of the birds also tended to use the fundamental frequency as a discriminative cue when the number of harmonics was few. These results indicate that birds use multiple strategies for this type of harmonic structure discrimination.

Acoustic Stimulation↗

PubMed1999

Learned control of slow potential interhemispheric asymmetry in schizophrenia.

We report on the feasibility of teaching 16 (DSM-IV) schizophrenic patients, subdivided by syndrome, self-regulation of interhemispheric asymmetry having demonstrated efficient learning of interhemispheric control in normal subjects. Reversal of asymmetry may be important to treatment and recovery in schizophrenia for following improvement on neuroleptic drugs functional hemispheric asymmetries have reversed, with directions of reversal and pre-existing asymmetry dependent on syndrome. Asymmetry reversal in animals, manifested by spatial turning tendencies, has been used as a marker of neuroleptic action and involves striatal dopamine under reciprocal hemispheric control. We gave as feedback the left right asymmetry in slow potential negativity recorded from the sensory motor strip (C3,4). Feedback took the form of a rocket on a screen which rose or fell with leftward or rightward shifts in negativity. Patients were able to learn control (P < 0.01). In those patients with lesser ability this was due to inability to sustain concentration throughout the session rather than slow initial learning. Active syndrome patients were better able to shift negativity rightward and withdrawn patients leftward, directions associated with drug reversal of functional asymmetry and symptom recovery for each syndrome. Accordingly our demonstration that many symptomatic schizophrenic patients are capable of learning control opens the door to electrocortical operant conditioning training in schizophrenia with therapeutic regimens.

Adult↗

PubMed1999

An examination of isomeric phenylpropanolamines in (-)ephedrine-trained rats.

A total of eight isomeric phenylpropanolamines are possible when the terminal amine is either an N-monomethylamine or a primary amine: (-)ephedrine, (+)ephedrine, (+)pseudoephedrine, (-)pseudoephedrine, (-)norephedrine, (+)norephedrine, (+)cathine, and (-)cathine. Few previous studies have examined the individual optical isomers of these phenylpropanolamines and, with the exception of one report on locomotor effects, no comparative behavioral data have been published on this series of agents. Using rats trained to discriminate 4 mg/kg of (-)ephedrine (i.p.) from saline vehicle using standard operant conditioning with a VI 15-s schedule of reinforcement, all eight agents were examined in tests of stimulus generalization. The (-)ephedrine stimulus (ED50 = 0.90 mg/kg) generalized to (+)ephedrine (ED50 = 2.64 mg/kg), (+)pseudoephedrine (ED50 = 6.58 mg/kg), (-)norephedrine (ED50 = 1.86 mg/kg), (+)norephedrine (ED50 = 5.75 mg/kg), and (+)cathine (ED50 = 4.87 mg/kg). The (-)ephedrine stimulus failed to generalize to either (-)pseudoephedrine or (-)cathine; the latter agents produced a maximum of 29 and 31% (-)ephedrine-appropriate responding, respectively. Thus, (a) six of the eight phenylpropanolamines produced ephedrine-like stimulus effects, (b) (-)ephedrine was the most potent of the examined agents, and (c) where stimulus generalization occurred, ED50 values spanned less than a tenfold range.

Animals↗

PubMed2002

Gap detection threshold in the rat before and after auditory cortex ablation.

Gap detection threshold (GDT) was measured in adult female pigmented rats (strain Long-Evans) by an operant conditioning technique with food reinforcement, before and after bilateral ablation of the auditory cortex. GDT was dependent on the frequency spectrum and intensity of the continuously present noise in which the gaps were embedded. The mean values of GDT for gaps embedded in white noise or low-frequency noise (upper cutoff frequency 3 kHz) at 70 dB sound pressure level (SPL) were 1.57+/-0.07 ms and 2.9+/-0.34 ms, respectively. Decreasing noise intensity from 80 dB SPL to 20 dB SPL produced a significant increase in GDT. The increase in GDT was relatively small in the range of 80-50 dB SPL for white noise and in the range of 80-60 dB for low-frequency noise. The minimal intensity level of the noise that enabled GDT measurement was 20 dB SPL for white noise and 30 dB SPL for low-frequency noise. Mean GDT values at these intensities were 10.6+/-3.9 ms and 31.3+/-4.2 ms, respectively. Bilateral ablation of the primary auditory cortex (complete destruction of the Te1 and partial destruction of the Te2 and Te3 areas) resulted in an increase in GDT values. The fifth day after surgery, the rats were able to detect gaps in the noise. The values of GDT observed at this time were 4.2+/-1.1 ms for white noise and 7.4+/-3.1 ms for low-frequency noise at 70 dB SPL. During the first month after cortical ablation, recovery of GDT was observed. However, 1 month after cortical ablation GDT still remained slightly higher than in controls (1.8+/-0.18 for white noise, 3.22+/-0.15 for low-frequency noise, P<0.05). A decrease in GDT values during the subsequent months was not observed.

Acoustic Stimulation↗

PubMed2002

Perception of the periodicity strength of complex sounds by the chinchilla.

The perception of periodicity strength was studied in chinchillas using a stimulus generalization paradigm in an operant-conditioning, positive reinforcement behavioral task. Stimuli consisted of cosine-phase and random-phase harmonic complex tones, infinitely iterated rippled noises, and wideband noise. These stimuli vary in periodicity strength as measured by autocorrelation functions and are known to generate a continuum in the perception of pitch strength in human listeners. Chinchillas were trained to discriminate a cosine-phase harmonic tone complex from wideband noise and tested in the generalization paradigm using random-phase tone complexes and iterated rippled noises as probe stimuli. Chinchillas were tested in three different conditions in which the periods of the fundamental frequencies of the tone complexes were fixed at 2 ms, 4 ms, or 8 ms. Behavioral responses obtained from chinchillas were related to stimulus periodicity strength. For most animals, the behavioral responses to random-phase tone complexes were smaller than those to cosine-phase tone complexes. The behavioral responses were analyzed in terms of the Auditory Image Model of Patterson et al. [Patterson, R.D., Allerhand, M.H., Giguère, C., J. Acoust. Soc. Am. 98 (1995) 1890-1894], and the results suggest that the periodicity information in the stimulus envelope has a large influence in controlling the behavioral response of the chinchilla. Comparison of the generalization data obtained in the present study to magnitude estimation data obtained previously in human subjects suggests a greater influence of stimulus envelope for the perception of periodicity strength in chinchillas than for the perception of pitch strength in human listeners.

Animals↗

PubMed1998

Chronic acamprosate eliminates the alcohol deprivation effect while having limited effects on baseline responding for ethanol in rats.

Acamprosate (calcium-acetyl homotaurinate) is a relatively new compound developed for the treatment of alcoholism and has been shown to be effective in attenuating relapse in human alcoholics. In the current study, the effects of this drug were further examined using an animal model of oral ethanol self-administration in a limited access paradigm. Male Wistar rats were trained to respond for ethanol (10% w/v) or water in a two-lever free-choice operant condition. Acute administration of acamprosate (400 mg/kg) reduced ethanol consumption and increased responding for water. Chronic administration of lower daily doses of acamprosate (100 and 200 mg/kg) blocked the increased ethanol consumption typically observed in rats after an imposed abstinence period. This effect of acamprosate was selective for ethanol, as responding for water was unaffected at any dose tested. These results with rats suggest a model by which to explore the mechanisms for anti-relapse effects of acamprosate.

Acamprosate↗