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At least 19 recordsLinked to original sources

Self-injurious behavior in Rett syndrome: interactions between features of Rett syndrome and operant conditioning.

Operant and biological theories of the cause of self-injurious behavior (SIB) in people with a mental handicap are often viewed as mutually exclusive. In this single case study, interactions between features of Rett syndrome and operant conditioning as determinants of SIB are examined. Functional analysis by analog methodology indicated different functions for two forms of SIB shown by the subject: automatic reinforcement by sensory stimulation and escape from social interactions. It is suggested that features of Rett syndrome established conditions under which operant conditioning of self-injurious responding was maximized. The implications of this interaction between features of syndromes and operant conditioning for the conceptualization of the cause of SIB are discussed and it is proposed that the notion of a unitary cause of SIB is inappropriate. It is more productive to consider operant conditioning as the process that maintains responding against a background of predisposing and mediating factors which may be biologically determined.

Child, Preschool↗

Contingent-dependent enhancement of rhythmic motor patterns: an in vitro analog of operant conditioning.

Operant conditioning is characterized by the contingent reinforcement of a designated behavior. Previously, feeding behavior in Aplysia has been demonstrated to be modified by operant conditioning, and a neural pathway (esophageal nerve; E n.) that mediates some aspects of reinforcement has been identified. As a first step toward a cellular analysis of operant conditioning, we developed an in vitro buccal ganglia preparation that expressed the essential features of operant conditioning. Motor patterns that represented at least two different aspects of fictive feeding (i.e., ingestion-like and rejection-like motor patterns) were elicited by tonic stimulation of a peripheral buccal nerve (n.2,3). Three groups of preparations were examined. In a contingent-reinforcement group, stimulation of E n. was contingent on the expression of a specific type of motor pattern (i.e., either ingestion-like or rejection-like). In a yoke-control group, stimulation of E n. was not contingent on any specific pattern. In a control group, E n. was not stimulated. The frequency of the reinforced pattern increased significantly only in the contingent-reinforcement group. No changes were observed in nonreinforced patterns or in the motor patterns of the control and yoke-control groups. Contingent reinforcement of the ingestion-like pattern was associated with an enhancement of activity in motor neuron B8, and this enhancement was specific to the reinforced pattern. These results suggest that the isolated buccal ganglia expressed an essential feature of operant conditioning (i.e., contingent reinforcement modified a designated operant) and that this analog of operant conditioning is accessible to cellular analysis.

Action Potentials↗

Operant conditioning.

Operant behavior is behavior "controlled" by its consequences. In practice, operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive versus behavioral approaches to timing, the "gap" experiment and its implications, proportional timing and Weber's law, temporal dynamics and linear waiting, and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules, and self-control. We point out how linear waiting may be involved in timing, choice, and reinforcement schedules generally. There are prospects for a unified approach to all these areas.

Attention↗

Operant conditioning of antennal muscle activity in the honey bee (Apis mellifera L.).

Antennal movements of the honey bee can be conditioned operantly under laboratory conditions. Using this behavioural paradigm we have developed a preparation in which the activity of a single antennal muscle has been operantly conditioned. This muscle, the fast flagellum flexor muscle, is innervated by an identified motoneuron whose action potentials correlate 1:1 with the muscle potentials. The activity of the fast flagellum flexor muscle was recorded extracellularly from the scapus of the antenna. The animal was rewarded with a drop of sucrose solution whenever the muscle activity exceeded a defined reward threshold. The reward threshold was one standard deviation above the mean spontaneous frequency prior to conditioning. After ten conditioning trials, the frequency of the muscle potentials had increased significantly compared to the spontaneous frequency. The conditioned changes of frequency were observed for 30 min after conditioning. No significant changes of the frequency were found in the yoke control group. The firing pattern of the muscle potentials did not change significantly after conditioning or feeding. Fixing the antennal joints reduces or abolishes associative operant conditioning. The conditioned changes of the frequency of muscle potentials in the freely moving antenna are directly comparable to the behavioural changes during operant conditioning.

Animal Structures↗

Regional characteristics of electrical responses (in the band 1-225 Hz) in the cerebral cortex to conditioned stimuli in operant conditioning.

Power spectra of short-term (less than 1 sec) electrical responses to conditioned stimuli were studied over the frequency range 1-225 Hz in dogs during food-related operant conditioning. These spectra demonstrated regional characteristics in terms of energy levels and frequency composition. Responses were more marked in the visual and parietal areas of the left hemisphere. Power in responses to a differential stimulus were significantly lower than with responses to positive stimuli, mainly because of the high-frequency range (80-225 Hz); energy levels in these two situations were similar during prestimulus intervals. The frequency composition of responses was defined by a series of discrete frequencies in the gamma (30-80 Hz) and high-frequency ranges.

Analysis of Variance↗

Operant conditioning of brain steady potential shifts in man.

Steady potential shifts (SPS) recorded from the scalp were conditioned operantly by visual and acoustical feedback. Three groups of seven subjects were each tested with a different response-reinforcement contingency: positive reinforcement for a positive SPS after a cue stimulus, positive reinforcement for a negative SPS after a cue stimulus, and noncontingent reinforcement. The steady potential shifts learned under these three conditions differed significantly. Negative shifts were associated with subjective feelings of activation, positive shifts with inactivation. Cortical genesis and possible artifacts are discussed.

Action Potentials↗

Effect of controlled hypercapnia on cerebrospinal fluid pressure and operating conditions during transsphenoidal operations for pituitary macroadenoma.

Controlled hypercapnia was assessed for its effectiveness in raising cerebrospinal fluid pressure to enable descent of the suprasellar portion of pituitary macroadenomas during transsphenoidal surgery. The result was compared in a randomized, single blind trial with intermittent boluses of saline injected intrathecally. Intrathecal pressures were monitored in both groups. Twenty-seven of 29 patients in the study group and 25 of 28 patients in the control group reached the target pressure of 20 mm Hg. The mean ETCO2 at the time of maximum pressure was 42.34 +/- 4.75 mm Hg in the study group and 29.81 +/- 2.61 mm Hg in the control group, (P< .001). Mean arterial carbon dioxide was 46.90 +/- 6.55 and 31.42 +/- 4.87 mm Hg, respectively. Surgeons blinded to the technique assessed the descent of the tumor. The operating conditions were judged by the surgeons to be satisfactory for 20 patients in the study group and 17 patients in the control group. Both techniques were equally effective in raising intracranial pressure and in providing descent of the suprasellar component of the tumor. No untoward side effects occurred while using either technique. The authors conclude that controlled hypercapnia is effective in producing descent of the suprasellar portion of a pituitary adenoma.

Adenoma↗

Uncoupling of human short and long latency stretch reflex responses with operant conditioning.

Purpose: Successful operant conditioning of the biceps brachii spinal stretch reflex (SSR) has resulted in concurrent changes in the magnitude of long latency reflex responses (LLRRs). This finding suggests a coupling of the SSR and LLRR. The purpose of the present study was to downtrain the LLRR using operant conditioning and to observe any concurrent change in the SSR. Methods: Fourteen, able-bodied, human subjects were randomly assigned to either the control group or the training group. The LLRR and SSR responses were measured as magnitude of electromyographic response to a quick stretch of the elbow flexors, delivered by a torque motor. All the subjects attended fourteen sessions. The first six sessions were baseline sessions during which no conditioning or feedback occurred. The next eight sessions were the same as the baseline sessions (extended baseline sessions) for the control group; no feedback or operant conditioning of the LLRR occurred. The next eight sessions for the training group comprised the operant conditioning. Results: Operant conditioning of the LLRR resulted in a statistically significant reduction of that response within the training group and between the two groups. Also, operant conditioning of the biceps brachii LLRR did not result in concurrent changes in the magnitude of the SSR suggesting an uncoupling of these responses. Conclusions: The LLRR of the biceps brachii could be operantly conditioned without significant changes in the SSR which suggests that these two responses can be volitionally uncoupled.

Journal Article↗

Operant conditioning of epileptic neurons in monkeys and its theoretical application to EEG operant conditioning in humans.

This paper reviews a series of previous reports which summarize the physiology of chronic experimental epileptic foci in monkeys. It is shown that such monkeys can be trained to bidirectionally control the firing rates of normal and epileptic neurons which comprise the epileptic focus. As a result of this acquired operant performance, the monkeys show both a decrease in clinical seizures as well as a decrease in single unit epileptic activity. The EEG correlate of this change in single unit epileptic activity is generalized EEG desynchronization. The conclusion from these data would indicate epileptic neurons can be operantly controlled from and this control is not correlated with any specific EEG pattern. This brings to question the specificity of the SMR in EEG biofeedback paradigms which treat human epilepsy. This author feels that the result from such biofeedback studies are the result of the patient learning to manipulate electrical events within the CNS pathways through which the seizures propagates and is not contingent upon specific EEG frequencies.

Animals↗

Effects of operating conditions on the adhesive strength of Pseudomonas fluorescens biofilms in tubes.

Understanding the mechanical properties of biofilms, especially the force required to disrupt them and remove them from substrata is very important to development of antibiofouling strategies. In this work, a novel micromanipulation technique with a specially designed T-shaped probe has been developed to serve as an experimental means to measure directly the adhesive strength of biofouling deposits on the surface of a glass test stud. The basic principle of this novel technique is to pull away a whole biofilm accumulated on the surface of a glass test stud with T-shaped probe, and to measure simultaneously the force imposed on the biofilm. The adhesive strength between the biofilms and the surface to which they are attached, is defined as the work per unit area required to remove the biofilms from the surface. The biofouling experiments were performed on an elaborate design of a simulated heat exchanger system. A monoculture of Pseudomonas fluorescens was chosen as the fouling microorganism for the laboratory studies. Results indicate that the adhesive strength of the biofilm was affected by the conditions of operation, such as biofilm age, nutrient concentration, suspended cell concentration, pH, surface roughness of the substratum and fluid velocity. As noted, the effect of fluid velocity on the biofilm adhesive strength seemed to overwhelm other factors. At the same operating conditions, the biofilm adhesive strength increased as the fluid velocity increased within the range of 0.6-1.6m/s. In addition, the flow-related biofilm structures were observed that biofilms generally grew as a more compact pattern at the higher fluid velocity. Apparently, the fluid velocity can affect the biofilm structure, which in turn determines the biofilm adhesive strength. The knowledge of the biofilm adhesive strength with associated influences of the operating conditions may be used to define better cleaning procedures.

Bacterial Adhesion↗

Feeding behavior of Aplysia: a model system for comparing cellular mechanisms of classical and operant conditioning.

Feeding behavior of Aplysia provides an excellent model system for analyzing and comparing mechanisms underlying appetitive classical conditioning and reward operant conditioning. Behavioral protocols have been developed for both forms of associative learning, both of which increase the occurrence of biting following training. Because the neural circuitry that mediates the behavior is well characterized and amenable to detailed cellular analyses, substantial progress has been made toward a comparative analysis of the cellular mechanisms underlying these two forms of associative learning. Both forms of associative learning use the same reinforcement pathway (the esophageal nerve, En) and the same reinforcement transmitter (dopamine, DA). In addition, at least one cellular locus of plasticity (cell B51) is modified by both forms of associative learning. However, the two forms of associative learning have opposite effects on B51. Classical conditioning decreases the excitability of B51, whereas operant conditioning increases the excitability of B51. Thus, the approach of using two forms of associative learning to modify a single behavior, which is mediated by an analytically tractable neural circuit, is revealing similarities and differences in the mechanisms that underlie classical and operant conditioning.

Adaptation, Physiological↗

Operant conditioning of gill withdrawal in Aplysia.

A basic question in neuroscience is how different forms of learning are related. To further address that question, we examined whether gill withdrawal in Aplysia, which has already been studied extensively for neuronal mechanisms contributing to habituation, sensitization, and classical conditioning, also undergoes operant conditioning. Animals were run in pairs. During the initial training period, the contingent (experimental) animal received a siphon shock each time its gill relaxed below a criterion level, and the yoked control animal received a shock whenever the experimental animal did, regardless of its own gill position. This was followed by an extinction period when there was no shock, a retraining period when both animals were contingent, and another extinction period. The experimental animals spent more time with their gills contracted above the criterion level than did the control animals during each period, demonstrating operant conditioning. The type of gill behavior modified by learning shifted over time: the experimental animals had a larger increase in the frequency and duration of spontaneous contractions than did the control animals during the first but not the last extinction period and a larger increase in the level of tonic contraction during the last but not the first extinction period. Because many of the neurons controlling spontaneous and tonic gill withdrawal have already been identified, it should now be possible to examine the cellular locus and mechanism of operant conditioning and compare them with those for other forms of learning of the same behavior.

Animals↗

Operant conditioning in the ant Myrmica sabuleti.

Operant conditioning could be obtained in the ant Myrmica sabuleti by presenting to the workers, during a six-day period, an apparatus containing either sugared water or meat as a reward. The conditioning obtained using sugared water as a reward was short lasting. A reconditioning was more persistent and lasted four hours. The ants' response was very precise, since they exhibited it only in front of an apparatus identical to that used during the training phase. Operant conditioning obtained using meat as a reward was more pronounced than that obtained by using sugared water, probably because meat is more valuable as a reward than sugar for the species studied, which is essentially a carnivorous one. Such a conditioning was rather persistent. Indeed, a first operant conditioning obtained by using meat as a reward could still be detected after seven hours, and a reconditioning was still significant after eight hours. One day after this eight-hour period without rewarding the ants, the response was higher again and a further day later, it was still significant. Since the operant conditioning is easy to perform and quantify and since the ants' response is very precise, such a conditioning can be used for further studying M. sabuleti workers' visual perception.

Animals↗

Operant conditioning of the pain experience.

Two experiments were carried out to study operant conditioning of pain report. Further, it was investigated whether pain-related psychophysiological and psychological measures (skin conductance response and magnitude matching) could also be conditioned operantly. In both experiments subjects received 12 painful electric shocks of equal intensity. In Exp. 1 healthy subjects were assigned to either a control group or an up-conditioning group. Up-conditioning occurred by verbally rewarding increases in pain report and punishing decreases. Analyses indicated that up-conditioning of both pain report and the pain-related psychophysiological measures succeeded. To rule out alternative explanations of the results (attention shift towards pain and conditioning of anxiety) the verbal punishments were adjusted in Exp. 2. A down-conditioning group was also added. The attempt to replicate the results of Exp. 1 failed and down-conditioning of the pain report could not be established. These inconsistent results are most probably due to modified punishment of responses. The consequences for the results of Exp. 1 are discussed. Based on the results of post hoc analyses, some suggestions are made for operant conditioning studies of pain.

Adolescent↗