The role of brain stimulation priming effects in self-deprivation

Choice of brain stimulation reward (BSR) over biologically necessary substances in some self-stimulating animals is referred to as self-deprivation. In several recent papers, it has been argued that this phenomenon is produced by the rewarding aspects of the brain stimulation. This conclusion is partially based on data showing that self-deprivation and brain stimulation reward increase and decrease in a similar manner in response to changes in the brain stimulation parameters. However, the priming aspects of the brain stimulation also fluctuate with changes in stimulation parameters. Therefore, changes in the priming rather than the rewarding aspects of the brain stimulation could be responsible for self-deprivation. To determine whether the priming effects of brain stimulation play an important role in self-deprivation, rats with bipolar stimulating electrodes were given the choice between BSR and food. Time-outs were enforced within each BSR/food competition session. Since priming effects decay over time, increasing time-out length should have decreased self-deprivation due to decay of priming. It was found that time-out length did not affect the degree of self-deprivation. It was concluded that self-deprivation is not mediated by the priming aspects of brain stimulation.     

A computerized system for monitoring and controlling intracranial electrical self-stimulation behavior

An automated system for measuring intracranial self-stimulation behavior is described. The system consists of two Commodore 6502 microcomputers interfaced with a constant-current generator and a standard operant chamber. The system hardware allows sine- and square-wave stimulation. Stimulus intensity can be varied in 256 steps between 0 and 100, 0 and 500, or 0 and 1,000 /µA. The system programs, which are written in machine language, allow the control of various schedules of reinforcement, the counting of operant responses and reinforcements, the measurement of interresponse intervals, and the storage of the data on disk. The software is designed for the determination of the threshold of reinforcement, on the basis of the titration of postreinforcement pauses caused by changeover in schedule control between concurrent continuous reinforcement and fixed ratio schedules.     

Preference paradigm: provides better self-stimulation reward discrimination than a rate-dependent paradigm

To obtain a better understanding of how well the Y-maze preference test paradigm indexes electrical brain stimulation reward, the present experiment compared the abilities of this rate-independent paradigm and a rate-dependent paradigm to assess the rewarding effectiveness of brain stimulation. The rate-dependent paradigm used was an operant chamber. The results showed that over a wide range of stimulation parameters the rate-independent paradigm provided a better assessment of the rewarding effectiveness of the brain stimulation than did the rate-dependent paradigm.     

The effects of reinforcer magnitude on timing in rats

The relation between reinforcer magnitude and timing behavior was studied using a peak procedure. Four rats received multiple consecutive sessions with both low and high levels of brain stimulation reward (BSR). Rats paused longer and had later start times during sessions when their responses were reinforced with low-magnitude BSR. When estimated by a symmetric Gaussian function, peak times also were earlier; when estimated by a better-fitting asymmetric Gaussian function or by analyzing individual trials, however, these peak-time changes were determined to reflect a mixture of large effects of BSR on start times and no effect on stop times. These results pose a significant dilemma for three major theories of timing (SET, MTS, and BeT), which all predict no effects for chronic manipulations of reinforcer magnitude. We conclude that increased reinforcer magnitude influences timing in two ways: through larger immediate after-effects that delay responding and through anticipatory effects that elicit earlier responding.     

Neural substrate for brain stimulation reward in the rat: cathodal and anodal strength-duration properties.

The trade-off between current strength and duration of a stimulating pulse was studied for the rewarding and priming effects of brain stimulation reward (BSR). With cathodal pulses, strenght-duration functions for BSR had chronaxies of .8-3 msec. No differences were observed between the results for rewarding and priming effects. With anodal pulses. strength-duration curves were parallel to the cathodal curves at pulse durations of .1-5 msec, but at pulse durations greater than 5 msec the anodal curves showed a greater drop in required current intensity than did the cathodal curves. The parallel portion of the anodal curves was interpreted as due to anode-make excitation, and the drop at longer pulse durations was interpreted as due to anode-break excitation. Cathodal strength-duration functions for the motor effect elicited through the BSR electrodes had chronaxies of .15-.48 msec. Measurements of the latency of the muscle twitch confirmed that anode-make and anode-break excitation occurred, the latter becoming evident at pulse durations as brief as .3-.4 msec. The results provide quantitative characterization of cathodal and anodal strength-duration properties of the neural substrate for BSR and are discussed in terms of their value in guiding electrophysiological investigation of that substrate.     

NOVA SKED: A behavioral notation language for Data General minicomputers

A state notation language (NOVA SKED) for the experimental control and collection of data from operant behavior experiments by Data General NOVA series minicomputers is described. NOVA SKED is based on the SKED system written for the Digital Equipment Corporation PDP8 series of minicomputers. The NOVA SKED state notation syntax enables diagramming experimental procedures directly and precisely by the operant experimenter, who need not be familiar with computers. This syntax can then be compiled by the computer into programs that operate under the SKED run-time system (RTS). The SKED RTS operates in a timesharing mode that allows up to 16 experimental stations to function simultaneously and independently from each other. NOVA SKED is a “stand-alone” system that collects and stores data on digital magnetic tape.     

Detection by the guinea pig of acoustic stimulation and of electrical stimulation of the brain

A threshold procedure using operant behavioral techniques with positive reinforcement was developed after initial efforts with avoidance behavioral procedures proved unsatisfactory. In the first of three experiments the operant threshold procedure was tested by determining masked auditory thresholds for trains of clicks. In a second experiment, similar techniques were used to measure thresholds for electrical stimulation of the brain. The last experiment, again an auditory problem, involved a determination of the absolute thresholds for trains of short noise bursts as a function of the time between bursts. Middle ear malfunction proved to be a more severe problem than had been anticipated on the basis of reports in the literature. The threshold procedure, however, seems to be adequate for determination of absolute or masked thresholds with auditory or electrical stimuli.     

NOVA SKED II: A behavioral notation language utilizing the Data General Corporation real-time disk operating system

A software system (NOVA SKED) was developed for the experimental control and collection of data from operant behavior experiments that is compatible with the Data General Corporation real-time disk operating system (RDOS). NOVA SKED is based on the SKED state notation language originally implemented on Digital Equipment Corporation PDP-8 series of minicomputers. The system includes a compiler written in FORTRAN, a multitasking run-time system that can be configured to run up to 30 stations, a data back-up system, standard data manipulation programs and subroutines, and user manuals.     

Amplitude measures of operant response: Implementation with Apple Pascal

Because operant conditioning studies involving force of response as a dependent variable require high-speed A/D conversion, conventional operant software, which treats the input datum as a dimensionless event, is generally unsuited for this kind of work. The author describes a complete Apple-based hardware-software ensemble that measures and records on diskette the peak force, duration, time integral of force, and interresponse time for individual operant responses. Data acquisition and control programs were written in Apple Pascal linked to selected assembly language modules. The real-time base was derived from an inexpensive crystal clock interfaced     

Perhaps more Consideration of Pavlovian-Operant interaction May Improve the Clinical Efficacy of Behaviorally Based Drug Treatment Programs

Drug abuse remains costly. Drug-related cues can evoke cue-reactivity and craving, contributing to relapse. The Pavlovian extinction-based cue-exposure therapy (CET) has not been very successful in treating drug abuse. A functional operant analysis of complex rituals involved in CET is outlined and reinterpreted as an operant heterogeneous chain maintained by observing responses, conditioned reinforcers, and discriminative stimuli. It is further noted that operant functions are not predicated on Pavlovian processes but can be influenced by them in contributing to relapse; several empirical studies from the animal and human literature highlight this view. Cue-reactivity evoked by Pavlovian processes is conceptualized as an operant establishing/motivating operation. CET may be more effective in incorporating an operant-based approach that takes into account the complexity of Pavlovian-operant interaction. Extinction of the operant chain coupled with the shaping of alternative behaviors is proposed as an integrated therapy. It is proposed that operant-based drug abuse treatments (contingency management, voucher programs, and the therapeutic work environment) might consider incorporating cue-reactivity, as establishing/motivating operations, to increase long-term success—a hybrid approach based on Pavlovian-operant interaction

     

A minicomputer system for recording the dynamic properties of individual operant responses

A PDP-12 is used to conduct operant experiments in which peak force, duration, time integral of force, and interresponse time may each serve as the criterion response property for reinforcement, and all four properties are simultaneously recorded as dependent variables. Calibration, acquisition and control, and data analysis programs are described.     

Concurrent variation of response bias and sensitivity in an operant-psychophysical test

The yes-no signal detection procedure was applied to a single-response operant paradigm in which rats discriminated between a standard auditory intensity and attenuated comparison values. The payoff matrix was symmetrical (with reinforcing brain stimulation for correct detections and brief time-out for errors), but signal probability and intensity differences were varied to generate a family of isobias and isosensitivity functions. The d’ parameter remained fairly constant across a wide range of bias levels. Isobias functions deviated from a strict matching strategy as discrimination difficulty increased, although an orderly relation was maintained between signal probability value and the degree and direction of response bias.     

Exploring the limits and utility of operant conditioning in the treatment of drug addiction

This article describes a research program to develop an operant treatment for cocaine addiction in low-income, treatment-resistant methadone patients. The treatment's central feature is an abstinence reinforcement contingency in which patients earn monetary reinforcement for providing cocaine-free urine samples. Success and failure of this contingency appear to be an orderly function of familiar parameters of operant conditioning. Increasing reinforcement magnitude and duration can increase effectiveness, and sustaining the contingency can prevent relapse. Initial development of a potentially practical application of this technology suggests that it may be possible to integrate abstinence reinforcement into employment settings using salary for work to reinforce drug abstinence. This research illustrates the potential utility and current limitations of an operant approach to the treatment of drug addiction. Similar research programs are needed to explore the limits of the operant approach and to develop practical applications that can be used widely in society for the treatment of drug addiction.     

Operant discrimination of an interoceptive stimulus in rhesus monkeys

Five rhesus macaques monkeys surgically prepared with Thiry small intestinal (jejunum) loops and implanted brain electrodes were restrained in primate chairs and kept on 23-hr deprivation-feeding cycle. After being trained to press a lever for sugar pills on an FR 25 schedule of reinforcement, a discrimination training procedure was established. Lever presses were reinforced during the S(D)-a non-aversive mechanical stimulus applied to the internal walls of the Thiry loop by rhythmic inflation-deflation of a small latex balloon by air at the rate of one cycle per sec at 100 mm Hg pressure. The S(Delta) was the absence of the visceral stimulation. The monkeys successfully discriminated between presence and absence of the internal stimulus. A discrimination reversal was attempted and completed on one monkey. The results clearly show operant discrimination based on an interoceptive stimulus. Cortical and subcortical EEG records reflected the onset but not termination of the visceral stimulation.     

Integrating functional neuroimaging and human operant research: brain activation correlated with presentation of discriminative stimuli

Results of numerous human imaging studies and nonhuman neurophysiological studies on "reward" highlight a role for frontal, striatal, and thalamic regions in operant learning. By integrating operant and functional neuroimaging methodologies, the present investigation examined brain activation to two types of discriminative stimuli correlated with different contingencies. Prior to neuroimaging, 10 adult human subjects completed operant discrimination training in which money was delivered following button pressing (press-money contingency) in the presence of one set of discriminative stimuli, and termination of trials followed not responding (no response-next trial contingency) in the presence of a second set of discriminative stimuli. After operant training, subjects were instructed to memorize a third set of control stimuli unassociated with contingencies. Several hours after training, functional magnetic resonance imaging was performed while subjects viewed discriminative and control stimuli that were presented individually for 1,500 ms per trial, with stimulus presentations occurring, on average, every 6 s. Activation was found in frontal and striatal brain regions to both sets of discriminative stimuli relative to control stimuli. In addition, exploratory analyses highlighted activation differences between discriminative stimuli. The results demonstrate the utility of coupling operant and imaging technologies for investigating the neural substrates of operant learning in humans.     

An animal restraint for the study of high-resistance operants in the rat

An animal restraint system and response operandum suitable for the study of operant behavior in the rat is described. This system combined with an inexpensive Commodore microcomputer and Psychronix interface is well-suited for the study of response parameters. Rats voluntarily entered the restraint, showed no observable signs of excess stress, and were easily extricated at the end of the experimental session. A lever-pressing operant with an adjustable force requirement was readily shaped using automated procedures. Although this system was designed for the study of high-resistance operants, it has potential advantages for other operant applications, including studies of visual discrimination and experiments requiring restraint due to physiological recording.     

Inexpensive microcomputer networking for laboratory research

Described is a low-cost laboratory network that has allowed us to conduct “on-line” animal research for the past 2 years. A Commodore Model 4032 microcomputer is used to download machine language programs to a network of SYM-1 single-board computers, which in turn each drive several operant stations. Data collected by the SYM-1s are then uploaded to the CBM 4032 after the session, and are then processed and stored on disk.     

A microcomputer-controlled laboratory: Software

The software used in a microcomputer-controlled laboratory is described. Primary emphasis is placed upon describing the capabilities of a powerful, easy-to-use programming language appropriate for controlling research in a wide variety of applications. It is particularly appropriate for physiological and operant laboratories. Design of the language and accompanying operating system follow a rigorous modular, structured approach, with most coding done in high-level languages. As a result, the code is easy to maintain and expand. In addition, it is not difficult to adapt the programs to other microprocessors to take advantage of a rapidly improving technology.     

A Commodore 64-based interface system for the operant laboratory

A system of interfaces for the Commodore 64 (C-64) microcomputer for use in the operant laboratory is described. This system frees the experimenter from limitations on the number of I/O lines available on the user port of the C-64 and offers the control of operant chambers for a low cost. Subroutines in machine code to control the interfaces, offering millisecond timing of external events, are presented. A sample BASIC program demonstrates how the subroutines are called from BASIC to run a simple discrimination experiment.     

DIFFERENTIAL RESPONSE PATTERNS TO THE CONTROL CONDITION BETWEEN TWO PROCEDURES TO ASSESS SOCIAL REINFORCERS FOR CHILDREN WITH AUTISM

Historically, reinforcer assessment procedures focus primarily on identifying nonsocial reinforcers (e.g., tangibles and edibles). Far less empirical attention has been allocated to the systematic identification of social consequences that function as reinforcers. This discrepancy is problematic given that social consequences are commonly incorporated into behavioral treatment programs without systematic evaluation of their efficacy. In this study, two methodologies (a single operant and a concurrent choice) were used to assess social reinforcers for children with autism. Results highlighted differences in response allocation to the control condition between procedures. Specifically, responding occurred in the control condition of the single‐operant procedure but not in the concurrent‐operant procedure. These differences highlight the need for further evaluation of procedures to assess social reinforcers. Copyright © 2013 John Wiley & Sons, Ltd.