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Results for “Conditioning, Operant”

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PubMed1983

Enhancement of learning four weeks after stimulation of the nucleus locus coeruleus in the rat: differential effects of dorsal noradrenergic bundle lesion and lesion of the locus coeruleus proper.

In previous studies we showed that electrical stimulation of the nucleus locus coeruleus produced, four weeks later, a significant improvement in performance in acquisition of food-reinforced operant conditioning. In the two experiments reported here, we tested the role of the dorsal noradrenergic bundle and of the locus coeruleus proper in this long-term effect. Lesioning the dorsal noradrenergic bundle did not have a clear and consistent effect, whereas lesion of the nucleus coeruleus proper suppressed almost totally the beneficial effect of the stimulation. In the first experiment, the dorsal noradrenergic bundle was lesioned by local bilateral injection of 6-hydroxydopamine, 8 days before stimulation of the locus coeruleus. Four weeks after the stimulation, the rats were tested for acquisition of the operant task. Three control groups were used: not lesioned but stimulated, lesioned but not stimulated, and not lesioned/not stimulated. The locus coeruleus stimulation produced the same improvement of performance at the beginning of the acquisition, whether or not the dorsal noradrenergic bundle had been lesioned. However, a significant decrement of performance was observed in lesioned and stimulated rats during the last 40 min of the acquisition. In the second experiment, the locus coeruleus proper was destroyed by bilateral local injection of 6-hydroxydopamine and the locus coeruleus region was stimulated 15 days later. Three control groups were used, as in the first experiment. All the rats were tested 4 weeks later for acquisition of the operant task. The locus coeruleus lesion significantly attenuated the beneficial effect of the stimulation; however, the performance of the lesioned and stimulated rats was still significantly superior to that of the lesioned but not stimulated rats. These results suggest that the noradrenergic locus coeruleus system is involved in the long-term effect, but that the rostral projections passing through the dorsal bundle, in front of the lesion, are not critically involved in the observed effect.

Animals↗

PubMed2004

Resistance to extinction: a measure of orbitofrontal function suitable for children?

Extinction of operantly conditioned responses, which provides a measure of the ability to adapt to changes in the reinforcement value of stimuli, has been linked to orbitofrontal cortex (OFC) in human and non-human animals. This article examines the feasibility of using extinction as a measure of the development of OFC function in preschool-age children. If extinction serves as a measure of OFC function, resistance to extinction should decrease during this age range. In Part 1, we review the literature on extinction as related to OFC, and summarize what is known regarding age-related changes in extinction in young children. In Part 2, we report results of a study assessing extinction in children between 3 and 6 years of age. Results revealed age-related increases in responding during extinction, with girls (particularly, 6-year-old girls) exhibiting stronger resistance to extinction. Some relations were found with temperament and normative compulsive-like behavior. The findings of this study question the utility of extinction of operant responding as a measure of OFC function in young children.

Adaptation, Psychological↗

PubMedDate not supplied

Network activity in neurons of the motor and prefrontal areas of the cortex in trained cats in conditions of systemic administration of m-cholinoreceptor blockers.

Experiments on five cats already trained to an operant conditioned food-procuring reflex to light were used to study the network activity of cells in the frontal and motor areas of the cortex accompanying disruption of conditioned reflex behavior in conditions of systemic administration of m-cholinoreceptor blockers. The activity of cortical neurons and their network properties were assessed using auto- and cross-correlation histograms. Doses of central m-cholinoreceptor blockers (the non-selective blocker scopolamine and the relatively selective m1-cholinoreceptor blocker trihexyphenidyl) disrupted performance of the operant motor reflex but had no effect on the appearance of contextual behavior and responses to switching on of the conditioned signal (standing up, elevating the paw). This was accompanied by 1) changes in the patterns of neuron activity in the moor and frontal areas of the cortex, with increases in train, rhythmic, and rhythmic train activity in cortical cells; 2) appearance of synchronicity in the operation of cortical neurons; 3) decreases in the numbers of direct interneuronal connections in the motor and frontal areas of the cortex and in the numbers of connections between these structures.

Animals↗

PubMed1993

Operant responding controlled by milk or milk contaminated with alcohol as positive reinforcers in infant rats.

Infant rats during the first, second, or third week of life were tested in operant conditioning with uncontaminated milk or milk supplemented with 6.0% v/v absolute ethanol (EtOH) as the reinforcer. Relative to yoked controls, pups of each age group reinforced on a response-contingent basis exhibited a significantly higher rate of responding with either reinforcer. In terms of amount of reinforcement, milk induced a higher rate of lever pressing than did the EtOH-contaminated compound. Age-related differences in the onset of differential responding for plain milk and EtOH-contaminated milk suggested developmental changes in the effects of alcohol. In a second experiment, forced drinking of milk and EtOH-contaminated milk was compared in similar age groups. Patterns of intake resembled the patterns of operant responding controlled by the same substance in the first experiment. These experiments indicate that the presence of alcohol in milk partially inhibits the reinforcing capacity of uncontaminated milk. Nevertheless, the former compound is still effective as a positive reinforcer during the first weeks of life.

Animals↗

PubMed1989

Adjunctive treatment with low-dose polymyxin B improves operant response rates and latency in infant rats with Haemophilus influenzae type b meningitis.

Polymyxin B given in conjunction with ampicillin protects infant rats against death from overwhelming Haemophilus influenzae type b infection. This study was undertaken to examine whether polymyxin B would mitigate the effects of brain damage caused by meningitis. Six- to 7-d-old Sprague-Dawley rats were infected subcutaneously into the nape with 10(7) cfu Haemophilus influenzae type b strain Eagan. This dose consistently caused bacteremia (1.2 X 10(5) cfu/mL) and meningitis (0.5 X 10(5) cfu/mL) in pilot studies. Twenty-four h after infection, all animals received intraperitoneal treatment consisting in either ampicillin alone (400 mg/kg X 4 q 3 h) repeated 12 h later, n = 15 or combined with polymyxin B (0.1 mg/kg/dose) n = 16. At age 2 mo, they were taken off ad libitum feeding and maintained at 80% of their wt. They were then conditioned to receive a food pellet by pressing a lever (continuous reinforcement). The next day, the time lapse between placement and pressing the lever for the first time was recorded (conditioned operant response or latency). Three wk later, the animals were put in the test chamber again and the time to press the lever (latency), as well as the time required to obtain 100 pellets (rate) were recorded. Animals who received polymyxin B had a significantly shorter reaction time; mean 34 s, SEM +/- 5.7 versus mean 88 s, SEM +/- 26.3, P less than or equal to 0.05 and performed significantly faster in obtaining 100 pellets; mean 925 s, SEM +/- 72.1 versus mean 1283 s, SEM +/- 126.3, p less than or equal to 0.02 (analysis of variance, Scheffé test).(ABSTRACT TRUNCATED AT 250 WORDS)

Ampicillin↗

PubMed2003

Associative olfactory learning of honeybees to differential rewards in multiple contexts--effect of odor component and mixture similarity.

Discrimination among differentially rewarding flowers allows honeybees to maximize their foraging efficiency. We studied how honeybees are able to relate to differential positive rewards when the odor representations are either structurally dissimilar, structurally similar (or form a substrate-product duo in planta), or form a binary mixture sharing a common constituent. Bees were tested both in conditioning of the proboscis-extension response (PER) and in a free-flying context. Our results point to honeybees using olfactory associative learning to differentiate between two positively rewarded odors. In PER, subjects discriminated best between dissimilar odors; they initially generalized between similar odors, but eventually learned to discriminate between them. The discrimination between mixtures sharing a common constituent remained poor. Likewise, the difference in visits to low- and high-rewarding flowers of free-flying bees was greater for dissimilar odors than for binary mixtures sharing a common constituent. Consequences of the operant conditioning nature of the free-flying context are discussed.

Animals↗

PubMed2004

Interneuronal frontohippocampal interactions in cats trained to choose on the basis of reinforcement quality.

Six cats were trained to food-related operant conditioned reflexes to light using the "active choice" of reinforcement method: short-latency pedal pressings were reinforced with meat and bread, while long-latency responses were reinforced with meat. Animals were divided in terms of their behavioral strategies: four preferred long-latency pedal pressings (the "self-controlled" group), while the other two preferred short-latency pedal pressings ("impulsive" animals). Implanted Nichrome semimicroelectrodes were used to record multicellular activity in the frontal cortex and hippocampus (field CA3). Interactions of neighboring neurons within the frontal cortex and the hippocampus (local neuronal networks) and between frontal cortex and hippocampal neurons (distributed neural networks in the frontohippocampal and hippocampofrontal directions) were assessed by statistical cross-correlation analysis of spike series with analysis epochs of 100 msec. The number of cross-correlational connections between the discharges of neurons in both local and distributed networks were significantly greater in the group of animals demonstrating self-control, i.e., preferring long-latency pedal pressings to receive the more valuable reinforcement. It is suggested that the predominance of functional interneuronal connections in the local networks of the frontal cortex and hippocampus and in frontohippocampal distributed networks in animals operating in the self-control regime as compared with impulsive animals demonstrates the dominant role of these informational structures in the organization of self-controlled behavior.

Animals↗

PubMed1979

A conditioning analysis of infant long-term memory.

The long-term retention of conditioned operant footkicks by 3-month-old infants was assessed in 2 studies. In both, infants were trained in a conjugate reinforcement paradigm in which footkicks produced conjugate activation of the components of an overhead crib mobile. After 2 training sessions, retention (cued recall, savings) was assessed cross-sectionally in a third session scheduled after varying intervals. In experiment 1, 32 infants were tested after intervals of 48, 72, 96, or 120 hours; in experiment 2, 24 infants were tested after 96, 144, 192, or 336 hours. No evidence of forgetting was observed for as long as 192 hours following original training. Although both retention measures indicated a significant memory deficit in the group tested after 336 hours (2 weeks), some individuals continued to exhibit substantial recall and savings after this retention interval. A conditioning analysis was viewed as a logical means by which to bridge the gap between animal and adult human models of memory.

Attention↗

PubMed2006

Neurophysiological aspects of primary insomnia: implications for its treatment.

Insomnia has usually been studied from a behavioral perspective. Somatic and/or cognitive conditioned arousal was shown to play a central role in sleep complaints becoming chronic, and was used as a starting point for the development of treatment modalities. The introduction of the neurocognitive perspective, with its focus on cortical or CNS arousal, has given rise to a renewed interest in the neurophysiological characteristics of insomnia. Recent research, using quantitative EEG, neuroimaging techniques and the study of the microstructure of sleep, suggests a state of hyperarousal with a biological basis. Furthermore, insomnia might not be restricted to sleep complaints alone because it appears to be a 24-h disorder, affecting several aspects of daytime functioning as well. These new findings have implications for the treatments used and indicate that a focus on cortical or CNS arousal should be pursued. As such, the use of EEG neurofeedback, a self-regulation method based on the paradigm of operant conditioning, might be a promising treatment modality. Preliminary results for insomnia and successful applications for other disorders suggest that this treatment can have the necessary stabilizing effects on the EEG activity, possibly resulting in a normalizing effect on daytime as well as nighttime functioning.

Arousal↗

PubMed2003

Feasibility study of sequencing batch reactor system for upgrading wastewater treatment in Malaysia.

The objective of this study was to assess the feasibility of the Sequencing Batch Reactor (SBR) system for implementation in Malaysia. Theoretical, field, laboratory investigations, and modelling simulations have been carried out. The results of the study indicated that the SBR system was robust, relatively cost-effective, and efficient under Malaysian conditions. However, the SBR system requires highly skilled operators and continuous monitoring. This paper also attempted to identify operating conditions for the SBR system, which optimise both the removal efficiencies and the removal rates. The removal efficiencies could reach 90-96% for COD, up to 92% for TN, and 95% for SS. An approach to estimate a full operational cycle time, to estimate the de-sludging rate, and to control the biomass in the sludge has also been developed. About 4 hours react time was obtained, as 2.25 hours of nitrification with aerated slow fill and 1.75 hour of denitrification with HAc addition as an additional carbon source. Inefficient settling was one of the problems that affect the SBR effluent quality. The settling time was one hour for achieving Standard B (effluent quality) and 2 hours for Standard A.

Biomass↗

PubMed2003

A behavioral paradigm to judge acute sodium salicylate-induced sound experience in rats: a new approach for an animal model on tinnitus.

Behavioral conditioning studies on rats have been proven to be a valid animal model for the evaluation of acute and chronic phantom auditory experience (tinnitus). We developed an animal model for short-term, acute induced phantom auditory sensations in rats. Rats were trained in a conditioning chamber to actively access a liquid feeder whenever a constant white noise sound was present. During silence, no reward was given. Fulfilling the demands of animal protection laws for maximal avoidance of pain and fear, punitive paradigms were maximally reduced. After 15-17 learning sessions, all animals performed more accesses to the reward feeder during periods of sound than during periods of silence. Tinnitus was induced by the administration of sodium salicylate (350 mg/kg body weight) given 3 h before testing. The feeder access activity of a rat treated with salicylate was significantly increased during periods of silence, indicating a phantom auditory experience. The presumptive auditory experience was estimated to be comparable to a white noise sound of about 30 dB SPL rms. The activity increase was less pronounced for lower doses of sodium salicylate (150 mg/kg body weight) and was not found in animals trained on a dark-light paradigm, as expected. As the learning sessions of the operant conditioning were performed without pharmacological treatment, unintentional drug effects, for example, on learning and motivation of a rat were minimized in this behavioral paradigm. Furthermore, the behavioral changes reported here were shown to be a specific drug effect evoking a phantom auditory experience of a rat and cannot be explained by unspecific drug effects on motor activity, motivation, learning or hearing loss. The conditional paradigm is discussed in the context of its potential as a model for testing drugs that may have a therapeutic value in tinnitus research.

Acoustic Stimulation↗

PubMed2006

The effects of hydraulic retention time and feed COD concentration on the rate of hydrolysis of primary sewage sludge under methanogenic conditions.

A series of completely mixed methanogenic anaerobic digesters have been operated to determine the rate of hydrolysis of primary sewage sludge. The hydraulic retention time was reduced from 60 d to when the system failed (approximately 5 d), while the feed COD concentration was 40, 25, 13 and 2 gCOD/L. A steady state model based on first order kinetics was developed to simulate the hydrolysis rate at each retention time and feed concentration. With the mean value for the hydrolysis rate constant (0.992 +/- 0.492 d(-1)), this model was able to accurately predict the effluent COD for all steady state operating conditions. However, the effluent COD concentration was relatively insensitive to the exact value for this constant. The model provides a framework for analysis of anaerobic digestion experimental data, to enable meaningful comparisons.

Bioreactors↗

PubMed1985

Effects of neuroleptics on rate and duration of operant versus reflexive licking in rats.

Operant conditioning techniques were used to train one group of nine rats to lick a dry horizontal metal disk on a fixed ratio 15 schedule with water reinforcement delivered at a different location. Another group of seven rats licked reflexively from a water reservoir positioned with the same spatial arrangements as the metal disk. The distance the rats' rongues traversed (10 mm) to contact the licking surface was the same in both the operant and reflexive lick conditions. The effects of three neuroleptics, haloperidol (0.06, 0.12, 0.24, 1.0, 2.0 mg/kg), chlorpromazine (0.5, 1.0, 2.0 mg/kg) and clozapine (2.5, 5.0, 7.5 mg/kg) on average lick rate and median lick duration were assessed for both groups. Dose related decreases in average lick rate were observed in both groups of rats as a function of dose of each of these neuroleptics. Moreover, operant lick rates were proportionately more affected by neuroleptic treatment than were reflexive lick rates. The dose-response effect for the duration variable was different for the two lick conditions in that reflexive lick duration was lengthened as dose increased, whereas operant lick duration was lengthened only at the lower doses of these drugs. The differential effect of these neuroleptics on operant vs. reflexive licking suggests that neuroleptics attenuate selectively those responses that require relatively more conditioning to acquire. These results may be analogous to the initiation deficit that has been suggested to account for neuroleptics' selective attenuation of avoidance, while leaving relatively intact the escape response in escape/avoidance procedures.

Animals↗

PubMed2005

Simulation of corrosion product activity for nonlinearly rising corrosion on inner surfaces of primary coolant pipes of a typical PWR under flow rate transients.

For nonlinear accelerating corrosion, calculation of activated corrosion products on inner surfaces of primary coolant pipes have been done in a typical pressurized water reactor (PWR) under flow rate perturbations. Computer program CPAIR-P (Corrosion Product Activity In Reactors) (Deeba et al., 1999) has been modified to accommodate for time-dependent corrosion rates. Results, for (24)Na, (56)Mn, (59)Fe, (58)Co, (60)Co and (99)Mo, show that the specific activity in primary loop approaches equilibrium value under normal operating conditions fairly rapidly. Predominant corrosion product activity during operation is due to (56)Mn, and cobalt isotopes dominate the activity after shutdown of reactor. Flow rate perturbations and different types of rising corrosion rates were introduced in the system and effects on saturation activity were studied. For a linear decrease in flow rate and a constant corrosion rate, the total coolant activity and activity on pipe scale approaches higher saturation values when compared to normal condition values. With a nonlinearly accelerating corrosion, the behavior of specific activity changes considerably. The flow rate perturbations on specific activity for pipe scale results in a new saturation value which depends on both the changes in flow rate (Delta w) and equilibrium corrosion rate (C(s)) values. However, the time taken to reach the saturation activity depends on the slope of corrosion rate. For a slow pump coastdown, the activity does not show an initial drop when flow rate starts decreasing. It monotonically rises and follows the slope of corrosion rate. The peak value and decay of activity after scram are strong functions of flow rate and removal efficiencies.

Journal Article↗

PubMed2003

Reconsolidation of a long-term memory in Lymnaea requires new protein and RNA synthesis and the soma of right pedal dorsal 1.

Reconsolidation of a long-term memory (LTM) in the snail Lymnaea stagnalis can be disrupted by cooling, an RNA synthesis blocker (actinomycin D), and by specifically ablating the soma of a cell we know is a site of LTM consolidation (right pedal dorsal 1, RPeD1). Aerial respiratory behavior was conditioned operantly by applying a gentle tactile stimulus to the pneumostome area (the respiratory orifice) every time the snail began to open its pneumostome to perform aerial respiration. This resulted in a reduction of this behavior while leaving cutaneous respiration intact. One week after training one-half of the animals received a memory reactivation session, which was similar to the original training (i.e., animals received reinforcement). All animals then received 1 hr of cooling, an injection of actinomycin D or saline, or the soma ablation procedure. This was followed by a test for savings 4 hr or 4 d later, which was also similar to the original training. Only those animals that received both the memory reactivation session and the treatment showed memory impairment during the test for savings. That is, the impairment was contingent on memory reactivation. These data indicate that reconsolidation requires both new RNA and protein synthesis to stabilize a reactivated memory, and it demonstrates that the soma of RPeD1, a cell that we have shown previously to be required in the consolidation of an LTM, is necessary for reconsolidation. These data suggest that the critical molecular processes occurring during both consolidation and reconsolidation transpire in the same cell in Lymnaea.

Animals↗

PubMed2003

Model-based analysis of anaerobic acetate uptake by a mixed culture of polyphosphate-accumulating and glycogen-accumulating organisms.

An increasing number of studies shows that the glycogen-accumulating organisms (GAOs) can survive and may indeed proliferate under the alternating anaerobic/aerobic conditions found in EBPR systems, thus forming a strong competitor of the polyphosphate-accumulating organisms (PAOs). Understanding their behaviors in a mixed PAO and GAO culture under various operational conditions is essential for developing operating strategies that disadvantage the growth of this group of unwanted organisms. A model-based data analysis method is developed in this paper for the study of the anaerobic PAO and GAO activities in a mixed PAO and GAO culture. The method primarily makes use of the hydrogen ion production rate and the carbon dioxide transfer rate resulting from the acetate uptake processes by PAOs and GAOs, measured with a recently developed titration and off-gas analysis (TOGA) sensor. The method is demonstrated using the data from a laboratory-scale sequencing batch reactor (SBR) operated under alternating anaerobic and aerobic conditions. The data analysis using the proposed method strongly indicates a coexistence of PAOs and GAOs in the system, which was independently confirmed by fluorescent in situ hybridization (FISH) measurement. The model-based analysis also allowed the identification of the respective acetate uptake rates by PAOs and GAOs, along with a number of kinetic and stoichiometric parameters involved in the PAO and GAO models. The excellent fit between the model predictions and the experimental data not involved in parameter identification shows that the parameter values found are reliable and accurate. It also demonstrates that the current anaerobic PAO and GAO models are able to accurately characterize the PAO/GAO mixed culture obtained in this study. This is of major importance as no pure culture of either PAOs or GAOs has been reported to date, and hence the current PAO and GAO models were developed for the interpretation of experimental results of mixed cultures. The proposed method is readily applicable for detailed investigations of the competition between PAOs and GAOs in enriched cultures. However, the fermentation of organic substrates carried out by ordinary heterotrophs needs to be accounted for when the method is applied to the study of PAO and GAO competition in full-scale sludges.

Acetates↗

PubMed2005

Treatment of levafix orange textile dye solution by electrocoagulation.

The decolorization of the levafix orange textile dye in aqueous solution by electrocoagulation using aluminum sacrificial anode has been investigated. The process performance is analyzed in terms of decolorization efficiency and the important cost-related parameters such as electrode and energy consumptions, as a function of initial pH, conductivity, current density, initial dye concentration and electrolysis time. The present study proves the effectiveness of electrochemical treatment for the textile dye solution. 95% decolorization efficiency may be obtained at suitable operating conditions such as; current density 100 A/m(2), operating time 12 min and initial pH 6.4. The corresponding electrode and energy consumptions during the electrolysis were found to be 1.8 kg Al/kg dye and 35 k Wh/kg dye.

Color↗

PubMed2006

A pilot-scale evaluation of magnetic ion exchange treatment for removal of natural organic material and inorganic anions.

The objective of this research was to evaluate a magnetic ion exchange process (MIEX) for the removal of natural organic material (NOM) and bromide on a continuous-flow pilot-scale basis under different operating conditions and raw water characteristics. The most important operating variable was the effective resin dose (ERD), which is the product of the steady-state resin concentration in the contactor and the regeneration ratio. The raw water employed in this study had a moderate concentration of ultraviolet (UV)-absorbing substances and dissolved organic carbon (DOC), and a low turbidity, alkalinity, and concentration of competing anionic species. Experiments were conducted using the ambient raw water and raw water spiked with bromide, chloride, and sulfate. Substantial removal of UV-absorbing substances and DOC was achieved at ERDs as low as 0.16mL/L. Moderate bromide removal was achieved, depending on the ERD. Increasing the sulfate concentration resulted in decreased removal of UV-absorbing substances, DOC, and bromide. Consistent results were observed between the continuous-flow pilot plant tests and batch equilibrium studies.

Adsorption↗