Apple II/FIRST system control of electrical brain stimulation in the rabbit

An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning from uniphasic (Scandrett & Gormezano, 1980) and multiphasic (Johnson, 1981) response signals. The present paper details the development of an electrical brain stimulation system as a peripheral device to the Apple II/FIRST system. In addition, data are presented that document the capabilities of the EBS system to concurrently stimulate up to eight animals while values along the dimension of each of four stimulation parameters are manipulated by a program written in FIRST. In our judgment, the EBS system has a number of advantages over currently available commercial stimulators, including cost, number of sites that can be independently stimulated, and availability of complete software control.     

Microprocessor control and A/D data acquisition in classical conditioning

An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and to extract dependent variable measures of conditioning. With our selection of the Apple II microprocessor and an added hardware floating-point processor, we have been able to establish independent computer systems for each of our three conditioning laboratories at a fraction of the cost of our DEC PDP-8/e (which was interfaced to only one of our laboratories). Moreover, our software system, FIRST, an interactive, high-level, dictionary-based language, is a programming and control system whose flexibility and ease of programming far exceeds that experienced with our DEC PDP-8/e system (Millenson, Kehoe, Tait, á Gormezano, 1973; Tait & Gormezano, 1974). In our judgment, the Apple II/FIRST system is of unprecedented efficiency and versatility for the control, data acquisition, and data analysis of analog responses in classical conditioning experiments.     

Ruler vs. the Apple II/FIRST system analysis of analog signals in classical conditioning

In our judgment, the Apple II/FIRST system (Scandrett & Gormezano, 1980) is an efficient and versatile system for experimental control and data acquisition in classical conditioning experiments. However, these attributes would be of limited value if the system did not extract measures from our analog signals with a high degree of correspondence with our ruler measurement procedures. Accordingly, we determined the system’s validity in extracting measures of CR occurrence and CR latency in three conditioning experiments. Pearson productmoment correlation coefficients indicated a very satisfactory degree of agreement on measurements made by the Apple II/FIRST system and ruler. Moreover, intraclass correlations and analysis of variance procedures applied to percent CRs and CR latency revealed several small, but divergent, differences between ruler and computer measurement of CR latency across the three experiments. However, subsequent analyses of variance revealed that the number and pattern of significant sources of variation for ruler or computer measurements were virtually identical. Accordingly, we have concluded that our system can successfully replace our traditional method of ruler measurement.     

An Apple microcomputer system in physiological psychology

The use of microcomputers in physiological psychology has allowed many investigators to conduct experiments that previously required more costly devices. We describe some of the research requirements that led to our selection of an Apple II/FIRST microcomputer system (Scandrett & Gormezano, 1980) for investigations of the neurophysiological correlates of classical and instrumental conditioning.     

A minicomputer program for control and data acquisition in classical conditioning

A 4K PDP-8/E computer program package has been developed to control classical conditioning procedures, to collect response data, and to extract statistical summeries. In contrast with other existing behavioral control languages geared to digital data typical of discrete operant analyses, this program distinguishes itself by its ability to retrieve and analyze the analog data arising from phasic response systems such as the rabbit’s nictitating membrane. By means of a question-and-answer Teletype conversation with the E, the program establishes trial sequence and trial spacing parameters; CS and US duration, probability, and interstimulus interval; intertrial interval fractionation for recording intertrial response frequencies; and session length. Various versions of the program exist to compute statistical properties of the analog response data, to dump detailed trial-by-trial topographies, and to attach instrumental contingencies to subtle features of the real-time analog responding.     

A comparison of neuronal reactions during classical and instrumental conditioning under similar conditions

During the elaboration of an instrumental reflex, it is not obligatory to use a conditioned stimulus, which signals the necessity to generate an instrumental reaction in order to receive reinforcement. However, the presence of a conditioned stimulus simplifies analysis of instrumental reaction, which in this case is the response to the conditioned stimulus. On the other hand, it is necessary to distinguish between instrumental and classical conditioning, since in both cases the response to a conditioned stimulus increases. We studied neuronal analogs of classical and instrumental conditioning in the identified neurons responsible for the defensive closure of the pneumostome in the Helix mollusk under the same conditions. During classical conditioning, a mollusk received punishment after a tactile stimulus. During instrumental conditioning, a mollusk received punishment when an identified neuron did not generate an action potential in response to a tactile stimulus. The appearance of a painful stimulus did not depend on the generation or failure of a spike in the related control neuron. Another tactile stimulus, which was never paired with an unconditioned stimulus, was used as a discriminated stimulus. We also compared the behavior of such identified neurons during pseudoconditioning. The experiments were carried out in a semi-intact preparation. We examined how responses to the tactile and painful stimuli changed during different forms of training. It was shown that the dynamics of neuronal responses to a conditioned tactile stimulus were much more complex during instrumental conditioning and consisted of several phases. Throughout a learning session, neural system consecutively acquired information as to which kind of learning was presented, whether a reaction of the neural system must be generated or inhibited and which instrumental reaction is correct. We have demonstrated that response to a painful stimulus during classical conditioning decreases after short-term initial increase. However, during instrumental learning, the neurons controlling instrumental action remained highly sensitive to the unconditioned stimulus. Meanwhile, foreign neurons decreased their responses to the unconditioned stimulus. We may tentatively conclude that classical and instrumental paradigms are fundamentally different at the cellular level.     

Apple II/FIRST-Corvus networks

Our Apple II/FIRST hardware-software configuration is a cost-effective, powerful, and efficient system for experimental control, data collection, and signal analysis of research in conditioning, neurophysiology, psychopharmacology, and psychophysiology. The present report describes the enhancement of our data-processing capabilities by the addition of peripheral hardware configured to form Corvus multiplexer networks. These networks have transformed our array of Apple II/FIRST systems into multiprocessor facilities possessing the data-processing power and flexibility of far larger and more costly mainframe systems while retaining the benefits of the markedly reduced cost, great flexibility, and high processing speed of microprocessor-based systems.     

KIM and the rabbit: The use of the KIM-1 microprocessor to control classical conditioning of the rabbit’s nictitating membrane response

The KIM-1 microprocessor combined with a plug-board interface provides an inexpensive and highly flexible system for controlling classical conditioning of the rabbit’s nictitating membrane response. The system is described in the context of a program for differential conditioning.     

A minicomputer program for stimulus control and analog data for discrete trial paradigms in biological preparations: Classical conditioning

The application of computer technology to classical conditioning requires: control software that will repeatedly generate stimulus events, and analog-to-digital (A/D) recording capabilities for the resolution of analog data from phasic response systems (e.g., nictitating membrane extension, leg flexion). An earlier software package implemented on a 4K PDP-8/E (Millenson, Kehoe, Tait, & Gormezano, 1973) successfully met these requirements. However, the program’s capabilities were restricted to the presentation of only two unique stimuli with a maximum of 4 sec duration, and data reduction in only uniphasic response systems. The present program, employing the same hardware, relaxed these previous constraints and extended the range of data analysis through the revamping of the interactive assembler, operating system, and on-line data processing routines.     

Allocation of cognitive processing capacity during human autonomic classical conditioning

In each of two experiments, allocation of cognitive processing capacity was measured in college-student subjects during autonomic discrimination classical conditioning. A 7.0-sec delay paradigm was used to establish classically conditioned responses to a reinforced visual conditioned stimulus (CS+). Electrodermal responses were the primary measures of autonomic classical conditioning. Allocation of processing capacity was measured by monitoring performance on a secondary reaction-time (RT) task. The auditory secondary-task RT signal was presented before, and 300, 500, 3500, 6500, and 7500 msec following CS onset. The RT signal was also presented following properly and improperly cued shock unconditioned stimuli (UCSs). Significant discrimination classical conditioning was obtained in both experiments. Comparison with control subjects who did not receive the RT signals indicated that the presence of the RT signals did not interfere with the development of classical conditioning. Four principal findings were obtained with the secondary-task RT measure. First, RTs to signals presented during CS+ were consistently slower than RTs to signals presented during CS-. This finding indicates that greater capacity allocation occurred during CS+ than CS- and is consistent with recent cognitive interpretations of classical conditioning. Second, the largest capacity allocation (i.e., slowing of RTs) occurred 300 msec following CS+ onset. This finding is consistent with the notion that subjects are actively processing the signal properties of the CS+ at 300 msec following CS+ onset. Third, presentation of the UCS when improperly cued (following CS-) significantly increased capacity allocation, whereas presentation of the same UCS when properly cued (following CS+) did not affect capacity allocation. These findings indicate that subjects were actively prepared for the UCS following CS+ but not following CS- and that a surprising UCS elicits greater capacity allocation than does an expected UCS. Fourth, large electrodermal responders to the CSs exhibited patterns of capacity allocation during the CSs, particularly during the CS+, different from those of small electrodermal responders. In particular, they exhibited significantly longer RTs at 300 msec after CS+ onset than did the small responders, followed by a shortening of RT at 500 msec relative to the small responders. This finding suggests that large electrodermal responders devote greater processing capacity to significant environmental stimuli than do small responders and that their processing may begin and be completed more rapidly. All in all, the data indicate the complexity of the cognitive processes that occur during human classical conditioning and the usefulness of the secondary-task technique in integrating conditioning theories and psychophysiology with cognitive psychology.     

A minicomputer program for the resolution of response frequency and latency in classical conditioning preparations

This classical conditioning program is capable of controlling stimulus events and recording response data in experiments using the rabbit’s nictitating membrane and/or iaw-movement responses. The main features of the program, implemented on the PDP·12 computer, are the ability to resolve response latency within a 1 msec error range and to display the response topography on the computer’s cathode ray tube. The extreme accuracy in latency measurement cannot be duplicated either by conventional hand-scoring methods involving oscillographic records or by other minicomputer conditioning programs.     

PC operating system for measuring discrete biological responses during classical conditioning

A software package, written in C source code for MS-DOS 5.0 or higher IBM-compatible computers, was developed for the classical conditioning of discrete biological responses. The program’s primary functions include collecting and storing conditioning parameters, controlling presentation of stimuli, transforming discrete analog responses into dependent measures (e.g., CR frequencies and various measures of response topography), and generating data sets for use with commercial PC statistical packages. These functions were implemented in a windows-based user interface to increase the experimenter’s ease of use and to maximize efficiency in performing experimental procedures. Scrollable windows provide detailed visual displays that permit monitoring responses during conditioning and a review of each trial after the session is over. Additional software tools aid the visual inspection of response topographies, data manipulation, and calibration of the experimental apparatus. An overview of the system, its design objectives, and the user interface is presented.     

Modeling signal features of escape response: effects of cessation conditioning in "learned helplessness" paradigm

Six experiments examined the effects of signaling the termination of inescapable shock (cessation conditioning) or shock-free periods (backward conditioning) on later escape deficits in the learned helplessness paradigm, using rats (Sprague-Dawley and Bantin-Kingman). A cessation signal prevented later performance deficits when highly variable inescapable shock durations were used during pretreatment. The inclusion of short minimum intertrial intervals during pretreatment did not alter the benefits of cessation conditioning but eliminated the protection afforded by a safety signal. The beneficial effects of both cessation and backward signals were eliminated when a single stimulus signaled shock termination and a shock-free period. Finally, a combination of cessation and backward signals was found to be most effective in immunizing against the effects of subsequent unsignaled, inescapable shock on later escape performance. These data suggest that cessation conditioning may be crucial to the prophylactic action of an escape response.     

In vitro analog of classical conditioning of feeding behavior in aplysia

The feeding behavior of Aplysia californica can be classically conditioned using tactile stimulation of the lips as a conditioned stimulus (CS) and food as an unconditioned stimulus (US). Moreover, several neural correlates of classical conditioning have been identified. The present study extended previous work by developing an in vitro analog of classical conditioning and by investigating pairing-specific changes in neuronal and synaptic properties. The preparation consisted of the isolated cerebral and buccal ganglia. Electrical stimulation of a lip nerve (AT4) and a branch of the esophageal nerve (En2) served as the CS and US, respectively. Three protocols were used: paired, unpaired, and US alone. Only the paired protocol produced a significant increase in CS-evoked fictive feeding. At the cellular level, classical conditioning enhanced the magnitude of the CS-evoked synaptic input to pattern-initiating neuron B31/32. In addition, paired training enhanced both the magnitude of the CS-evoked synaptic input and the CS-evoked spike activity in command-like neuron CBI-2. The in vitro analog of classical conditioning reproduced all of the cellular changes that previously were identified following behavioral conditioning and has led to the identification of several new learning-related neural changes. In addition, the pairing-specific enhancement of the CS response in CBI-2 indicates that some aspects of associative plasticity may occur at the level of the cerebral sensory neurons.     

Operant Reward Learning in Aplysia

Anticipating the future has a decided evolutionary advantage, and researchers have found many evolutionarily conserved mechanisms by which humans and animals learn to predict future events. Researchers often study such learned behavior using conditioning experiments. The marine snail Aplysia has been at the forefront of research into the cellular and molecular mechanisms of classical conditioning. Recently, Aplysia has also gained a reputation as a valuable model system for operant reward learning. Its feeding behavior can be operantly conditioned in the intact animal as well as in reduced preparations of the nervous system. The reward signal relies on dopamine transmission and acts in conjunction with activity in an identified neuron (B51) to bring about operant memory.     

Varying temporal location of a conditioned stimulus in heart rate conditioning ofMacaca mulatta

The several functions that a stimulus can assume were investigated in a Pavlovian conditioning procedure. The subjects were six rhesus monkeys; the response under observation was heart rate. The conditioning began with a temporal separation of zero between a signal and a regularly repeating electric shock; the signal was then moved to a series of earlier locations in the inter-shock interval. After six sessions at each location, two sessions followed in which only the shock was delivered periodically. The findings included: (1) A two-phased conditioned cardiac rate response seen at the first location became more multiphasic and irregular during longer intervals between signal and shock; (2) the location where the conditioned response peaked became increasingly variable as the signal was moved back, but this variability maintained a constant proportion to the signal-shock interval; and, (3) heart rate during a presignal period, and during a comparable period in shock only sessions, was generally deceleratory early in training and acceleratory thereafter. Sessions with the signal showed heart rate in the presignal period to have become acceleratory earlier in training than sessions with shock only. The data pertain to stimulus control over heart rate as a function of: (A) the temporal proximity of a signal to an aversive stimulus; and, (B) the presence or absence of the signal. The use of appropriate response units in cardiac conditioning is also discussed.     

Tactile conditioning of an autonomic and somatic response in young infants

Tactile classical conditioning of an autonomic reflex (pupillary dilation and constriction) and a somatic response (eyeblinking) was attempted in two separate experiments with one-month-old infants. The tactile CS was effective for conditioning eyeblinking but was ineffective for elaborating conditional pupillary reflex dilation or constriction. These differences were related to the interaction between stimulus and response in infant conditioning and the source of nervous system innervation of the CR as it relates to conditionability.     

Classical conditioning in children with attention deficit hyperactivity disorder (ADHD) and anxiety disorders: A test of Quay's model

Quay (1988) put forward a model of childhood mental disorders based on Gray's (1982) theory that there exists within the brain a behavioral inhibition system (BIS), which processes signals related to aversive or punishing stimuli. According to this model, children with attention deficit hyperactivity disorder (ADHD) show lower than optimal levels of activity in this system, which leads to less responsiveness at a physiological level to signals related to punishment. Children with ADHD and controls were compared on a classical conditioning paradigm. Skin conductance and cardiac responses were measured in response to a conditioned stimulus that had been paired with an aversive unconditioned stimulus. There were no differences between the groups, suggesting that, in terms of classical conditioning, ADHD children are equally responsive to signals related to punishment as controls.This work was supported by a National Institute of Mental Health grant K11 MH00731.     

The effects of aversive conditioned stimuli on the timing of unsignalled avoidance responding in rats

Rats received unsignalled avoidance training in a shuttlebox. After acquisition, classical conditioning sessions were administered. The Excitatory Group received signals paired with shock, the Inhibitory Group received signals explicitly unpaired with shock, while the Random Control Group received signals and shocks randomly in time. When subsequently superimposed on the avoidance baseline, the excitatory signal increased response rate, the inhibitory signal decreased rate and the random signal had no effect compared to signal-only control data. Unsignalled avoidance generates temporal gradients of responding; the major purpose of this study was to determine how these rate changes were reflected in the baseline temporal behavior. Very clear and simple summation rules emerged: In the presence of the excitatory signal, rats acted as if they were ahead of their actual location in the response-shock interval regardless of where the signal occurred; the inhibitory signal had the opposite effect while the random signal did not change the temporal behavior relative to signal-only control data. These results were interpreted within a motivational framework.     

A microprocessor control system and solid state interface for controlling electrophysiological studies of conditioning

This paper describes a microprocessor control system and solid state interface for controlling the apparatus in combined behavioral-electrophysiological studies of conditioning. The computer program, which is designed to control classical conditioning of the rabbit’s nictitating membrane response, provides the flexibility to control all conditioning parameters (e.g., interstimulus and intertrial intervals, trial type, and sequence of trial types) with only minor modifications. The system is free from artifacts that can distort electrophysiological recordings and can easily be modified to accommodate other behavioral paradigms in which electrophysiological responses are recorded.