The analysis of multiphasic signals with the Apple II/FIRST microprocessor system

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 response signals (Scandrett & Gormezano, 1980). The present paper covers an expansion in the capabilities of the system by the development of a multiphasic signal analysis algorithm written in FIRST, an interactive, high-level, dictionary-based language. The program provides unprecedented efficiency, sensitivity, and flexibility in the analysis of multiphasic analog response signals in classical conditioning experiments. Moreover, the program has the potential to analyze even more complex signal patterns.     

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.     

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.     

Human classical conditioning. The status of the CS

Recent reports of failure to obtain blocking in human galvanic skin response (GSR) conditioning, together with our own equivocal results with eyelid conditioning, have motivated us to re-examine the status of the conditioned stimulus (CS) in human conditioning studies. The issues raised by compound stimuli, by contextual cues and occasion setting stimuli, and by cross-modal transfer are considered in the light of data from our laboratories. These data include observations on the interchangeability of stimulus modalities during acquisition, the use of varying information loads embedded in occasion setting displays, the comparison of alternative blocking designs and the analysis of response topography in relation to stimulus variability. They suggested that an adequate account of the CS in human conditioning studies must recognize that it is dynamically processed and reprocessed both during and after acquisition.     

A comparison of the effects of vicariously instigated classical conditioning and direct classical conditioning procedures

Two groups of Ss received either two or 16 paired classical conditioning trials beyond the peak CR. A third group received the same stimuli as in the 16 postpeak condition but in an unpaired and random order. The stimuli in all three groups were delivered directly to S. Subsequently, all three groups, including a fourth which was not given any prior direct classical conditioning, were exposed to vicariously instigated classical conditioning. This consisted of havingS observe someone (model) employed byE who received the same CS as was delivered during direct conditioning. The CS was paired with the feigned arm movement of the model, simulating a reaction to shock. This vicarious classical conditioning procedure when compared to direct classical conditioning resulted in smaller GSR magnitudes for both the CRs and UCRs. Previous experience with direct classical conditioning seems to have had an attenuating effect on GSR magnitude during the vicarious situation. A postexperimental questionnaire tended to support the results, and the relationship between the present study and current classical conditioning theory is discussed.     

Effects of real vs pretend shock on semantic differential judgments and the GSR in some classical conditioning paradigms

In two experiments subjects were shown different color 1-sec lights, one just before the end of a 4-sec UCS and the other coming 10 sec after UCS termination and 25 sec before the next UCS. For some groups the UCS was strong electric shock; for others it was a tone which subjects were instructed to imagine was a strong shock. The primary data were changes in semantic differential ratings of the lights before and after 12 “conditioning” trials. There were no differences among the groups. In a third experiment a 6-sec delay CS was used for GSR conditioning, some subjects receiving actual shock and others pretend shock. Only the former showed conditioning. The results are discussed in terms of a model of experimental demand.     

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.     

The role of contingency in classical conditioning

The assumption that classical conditioning depends on a contingent relation between the conditioned stimulus (CS) and the unconditioned stimulus (US), which was proposed some decades ago as an alternative to the traditional contiguity assumption, still is widely accepted as an empirical generalization, if no longer as a theoretical postulate. The first support for the contingency assumption was provided by experiments in which occasional CS-US pairings produced no response to the CS in random training--i.e., training in which the probability of the US was the same in the presence and absence of the CS. Those early experiments, the results of which too often are taken at face value, are reconsidered along with various later experiments that show conditioning, both of the CS and its context, in random training. The evidence suggests that CS-US contingency is neither necessary nor sufficient for conditioning and that the concept has long outlived any usefulness it may once have had in the analysis of conditioning.     

Extinction instead of incubation following classical aversive conditioning in dogs.

Two dogs received a single paired classical conditioning trial, with tone CS and 12 mA shock US. Both dogs then showed a conditioned blood pressure increase in response to the nonreinforced CS, which extinguished with additional nonreinforced presentations. The CR showed spontaneous recovery four days later, but reextinguished with additional nonreinforced presentations. The results were interpreted as not supporting Eysenck's theory of "incubation" following one-trial aversive conditioning.     

Hippocampal theta-dependent eyeblink classical conditioning: coordination of a distributed learning system

Richard F. Thompson's study of the neurobiological substrates of learning and memory has been a career-long endeavor, chosen early and pursued with uncompromising depth and breadth. His systematic mapping of the major brain systems and mechanisms involved in eyeblink classical conditioning (EBCC) established the essential role of the cerebellum. Investigations of the interactions between the hippocampus and cerebellum are critically important to this literature, given the essential involvement of these structures in trace EBCC as well as an important modulatory role of the hippocampus in delay EBCC. Hippocampal theta (3-7Hz) oscillations are known to reflect a functional state that influences both the timing of unit firing and the potential for neural plasticity in the hippocampus and other structures. Herein we present a brief summary of research demonstrating the behavioral enhancement due to theta and the underlying neurobiological correlates in both hippocampus and cerebellum during EBCC. Hippocampal and cerebellar local field potentials (LFPs) show that these distantly interconnected brain structures become precisely synchronized when conditions favor rapid behavioral acquisition. Our results suggest a major role for theta in coordinating the widely distributed memory system for trace EBCC. These and other important findings reflect Thompson's own work and his early-career mentoring of scientists whose contributions to the EBCC literature have ensured his major and lasting impact on the neurobiology of learning and memory.     

Reinforcement in an in vitro analog of appetitive classical conditioning of feeding behavior in Aplysia: blockade by a dopamine antagonist

In a recently developed in vitro analog of appetitive classical conditioning of feeding in Aplysia, the unconditioned stimulus (US) was electrical stimulation of the esophageal nerve (En). This nerve is rich in dopamine (DA)-containing processes, which suggests that DA mediates reinforcement during appetitive conditioning. To test this possibility, methylergonovine was used to antagonize DA receptors. Methylergonovine (1 nM) blocked the pairing-specific increase in fictive feeding that is usually induced by in vitro classical conditioning. The present results and previous observation that methylergonovine also blocks the effects of contingent reinforcement in an in vitro analog of appetitive operant conditioning suggest that DA mediates reinforcement for appetitive associative conditioning of feeding in Aplysia.