Behavior systems,associationism, and Pavlovian conditioning

Associative and behavior systems accounts of Pavlovian conditioning have different emphases. The traditional associative account has focused on the role of the unconditional stimulus (US) in strengthening stimulus associations according to a set of general laws. The behavior systems account has focused on the relation of conditional responding to the preorganized perceptual, motor, and motivational organization engaged by the US. Knowledge of a behavior system enables successful prediction of the form and ease of conditioning as a function of the type of conditional stimulus (CS), US, and the CS-US relation. At the same time, Pavlovian manipulations act as a window on how a behavior system works. Both associative and behavior systems accounts can be criticized as incomplete and idiosyncratic. A comprehensive account of Pavlovian conditioning could profit from their integration.     

Pavlov and the foundation of behavior therapy

The foundation, achievements, and proliferation of behavior therapy have largely been fueled by the movement's foundation in behavioral principles and theories. Although behavioral accounts of the genesis and treatment of psychopathology differ in the extent to which they emphasize classical or operant conditioning, the mediation of cognitive factors, and the role of biological variables, Pavlov's discovery of conditioning principles was essential to the founding of behavior therapy in the 1950s, and continues to be central to modern behavior therapy. Pavlov's reliance on a physiological model of the nervous system, sensible in the context of an early science of neurology, has had an implication for behavior therapists interested in the study of personality types. However, Pavlov's major legacy to behavior therapy was his discovery of "experimental neuroses," shown by his students Eroféeva and Shenger-Krestovnikova, to be produced and eliminated through the principles of conditioning and counter-conditioning. This discovery laid the foundation for the first empirically-validated behavior therapy procedure, systematic desensitization, pioneered by Wolpe. The Pavlovian origins of behavior therapy are analyzed in this paper, and the relevance of conditioning principles to modern behavior therapy is demonstrated. It is shown that Pavlovian conditioning represents far more than a systematic basic learning paradigm. It is also an essential theoretical foundation for the theory and practice of behavior therapy.     

Pavlovian conditioning of Hermissenda: current cellular, molecular, and circuit perspectives

The less-complex central nervous system of many invertebrates make them attractive for not only the molecular analysis of the associative learning and memory, but also in determining how neural circuits are modified by learning to generate changes in behavior. The nudibranch mollusk Hermissenda crassicornis is a preparation that has contributed to an understanding of cellular and molecular mechanisms of Pavlovian conditioning. Identified neurons in the conditioned stimulus (CS) pathway have been studied in detail using biophysical, biochemical, and molecular techniques. These studies have resulted in the identification and characterization of specific membrane conductances contributing to enhanced excitability and synaptic facilitation in the CS pathway of conditioned animals. Second-messenger systems activated by the CS and US have been examined, and proteins that are regulated by one-trial and multi-trial Pavlovian conditioning have been identified in the CS pathway. The recent progress that has been made in the identification of the neural circuitry supporting the unconditioned response (UR) and conditioned response (CR) now provides for the opportunity to understand how Pavlovian conditioning is expressed in behavior.     

Predicting danger: the nature, consequences, and neural mechanisms of predictive fear learning

The ability to detect and learn about the predictive relations existing between events in the world is essential for adaptive behavior. It allows us to use past events to predict the future and to adjust our behavior accordingly. Pavlovian fear conditioning allows anticipation of sources of danger in the environment. It guides attention away from poorer predictors toward better predictors of danger and elicits defensive behavior appropriate to these threats. This article reviews the differences between learning about predictive relations and learning about contiguous relations in Pavlovian fear conditioning. It then describes behavioral approaches to the study of these differences and to the examination of subtle variations in the nature and consequences of predictive learning. Finally, it reviews recent data from rodent and human studies that have begun to identify the neural mechanisms for direct and indirect predictive fear learning.     

Neural circuitry and plasticity mechanisms underlying delay eyeblink conditioning

Pavlovian eyeblink conditioning has been used extensively as a model system for examining the neural mechanisms underlying associative learning. Delay eyeblink conditioning depends on the intermediate cerebellum ipsilateral to the conditioned eye. Evidence favors a two-site plasticity model within the cerebellum with long-term depression of parallel fiber synapses on Purkinje cells and long-term potentiation of mossy fiber synapses on neurons in the anterior interpositus nucleus. Conditioned stimulus and unconditioned stimulus inputs arise from the pontine nuclei and inferior olive, respectively, converging in the cerebellar cortex and deep nuclei. Projections from subcortical sensory nuclei to the pontine nuclei that are necessary for eyeblink conditioning are beginning to be identified, and recent studies indicate that there are dynamic interactions between sensory thalamic nuclei and the cerebellum during eyeblink conditioning. Cerebellar output is projected to the magnocellular red nucleus and then to the motor nuclei that generate the blink response(s). Tremendous progress has been made toward determining the neural mechanisms of delay eyeblink conditioning but there are still significant gaps in our understanding of the necessary neural circuitry and plasticity mechanisms underlying cerebellar learning.     

Parallel neural systems for classical conditioning: Support from computational modeling

Classical conditioning has been explained by two main types of theories that postulate different learning mechanisms. Rescorla and Wagner (1972) put forth a theory in which conditioning is based on the ability of the US to drive learning through error correction. Alternatively, Mackintosh (1973) put forth a theory in which the ability of the CS to be associated with the unconditioned stimulus is modulated. We have proposed a reconciliation of these two mechanisms as working in parallel within different neural systems: a cerebellar system for US modulation and a hippocampal system for CS modulation. We developed a computational model of cerebellar function in eyeblink conditioning based on the error correction mechanism of the Rescorla-Wagner rule in which learningrelated activity from the cerebellum inhibits the inferior olive, which is the US input pathway to the cerebellum (Gluck et al., 1994). We developed a computational model of the hippocampal region that forms altered representations of conditioned stimuli based on their behavioral outcomes (Gluck & Myers, 1993; Myers et al., 1995). Overall, computational modeling and empirical findings support the idea that, at least in the case of eyeblink conditioning, there may be two different neural systems: the cerebellum which mediates US-based error correction and hippocampus which alters representations of CSs.     

Parallel Neural Systems for Classical Conditioning: Support From Computational Modeling

Classical conditioning has been explained by two main types of theories that postulate different learning mechanisms. Rescorla and Wagner (1972) put forth a theory in which conditioning is based on the ability of the US to drive learning through error correction. Alternatively, Mackintosh (1973) put forth a theory in which the ability of the CS to be associated with the unconditioned stimulus is modulated. We have proposed a reconciliation of these two mechanisms as working in parallel within different neural systems: a cerebellar system for US modulation and a hippocampal system for CS modulation. We developed a computational model of cerebellar function in eyeblink conditioning based on the error correction mechanism of the Rescorla-Wagner rule in which learning-related activity from the cerebellum inhibits the inferior olive, which is the US input pathway to the cerebellum (Gluck et al., 1994). We developed a computational model of the hippocampal region that forms altered representations of conditioned stimuli based on their behavioral outcomes (Gluck & Myers, 1993; Myers et al., 1995). Overall, computational modeling and empirical findings support the idea that, at least in the case of eyeblink conditioning, there may be two different neural systems: the cerebellum which mediates US-based error correction and hippocampus which alters representations of CSs.     

A software system for real-time control of psychological experiments

This paper describes an all-purpose experimental system, “APES,” for use in a microprocessor-controlled behavioral pharmacology laboratory. APES is an assembly language program that can run on any of the DEC PDP-11 family processors under an RT-11 single-job operating system. Its main purpose is the real-time control of psychological experimentation. The capabilities of the system are: (1) system generation of all operant or Pavlovian conditioning paradigms, (2) collection and storage of both behavioral and physiological data in a machine-readable format for later statistical analysis, and (3) operation that can be accomplished by individuals who have no computer programming experience.     

REVIEW OF THE BOOK SNIFFY THE VIRTUAL RAT PRO VERSION 2.0

Sniffy the Virtual Rat Pro Version 2.0 is the most recent update to the Sniffy the Rat program modules. It has an extensive set of simulations related to Pavlovian and operant conditioning. Many of the standard conditioning paradigms and phenomena are contained within this program. Pavlovian effects such as blocking, overshadowing, and stimulus competition are demonstrated in the data output. Operant manipulations allow shaping the behavior of the virtual rat, observing cumulative records of interval and ratio schedules, as well as conducting operant discrimination procedures. In both Pavlovian and operant paradigms, one can generate histograms that predict the degree to which various stimuli control the virtual rat's behavior. On‐screen presentations may keep most users interested, but working with the generated data files sometimes can prove difficult. Overall, this program has a strong potential for facilitating the instruction in undergraduate conditioning courses, serving as an addendum to traditional undergraduate conditioning laboratories and as a supplement to the use of live animals.     

Using pavlovian higher-order conditioning paradigms to investigate the neural substrates of emotional learning and memory

In first-order Pavlovian conditioning, learning is acquired by pairing a conditioned stimulus (CS) with an intrinsically motivating unconditioned stimulus (US; e.g., food or shock). In higher-order Pavlovian conditioning (sensory preconditioning and second-order conditioning), the CS is paired with a stimulus that has motivational value that is acquired rather than intrinsic. This review describes some of the ways higher-order conditioning paradigms can be used to elucidate substrates of learning and memory, primarily focusing on fear conditioning. First-order conditioning, second-order conditioning, and sensory preconditioning allow for the controlled demonstration of three distinct forms of memory, the neural substrates of which can thus be analyzed. Higher-order conditioning phenomena allow one to distinguish more precisely between processes involved in transmission of sensory or motor information and processes involved in the plasticity underlying learning. Finally, higher-order conditioning paradigms may also allow one to distinguish between processes involved in behavioral expression of memory retrieval versus processes involved in memory retrieval itself.     

The“response” in behavior theory

The term“response” is a basic one in behavior theory, particularly reflex theory, but its definition is not clear. The origin of the term in the common vocabulary has affected its later extensions in the analysis of behavior. Some contemporary theorists accept the existence of two“types” of response, coordinating one with the Pavlovian conditioning procedure, the other with the operant conditioning procedure of the so-called“contingent” variety. Reservations are expressed here about such distinctions between response classes and conditioning paradigms, emphasizing the difficulties that arise from certain conventions and inadequacies in current definitions and conceptions of“response.” The critical nature of the problem for behavior theory is illustrated once again by the recent laboratory finding that a familiar and accepted conditional reflex, that of the“conditioned cardiac CR,” can be fractionated into“parts” and is therefore perhaps no longer to be treated as a single unitary“response.”     

New Directions for a Classical Paradigm: Human Eyeblink Conditioning

Abstract—The knowledge base on neural substrates an mechanisms involved in classical eyeblink conditioning makes it an ideal paradigm for investigating fundamental issues in learning and memory. New applications for the model system presented here include its use in (a) assessment to evaluate neurocognitive development in infancy, (b) theory building in abnormal psychology to test relationships between obsessive-compulsive behavior and learning rate, (c) evaluation of hypotheses about brain memory systems, and (d) exploration of the role of brain structures such as the cerebellum in learning and timing. Human eyeblink conditioning is a prototype of the utility of a model system that has become well characterized at both the behavioral and the neurobiological levels.     

Neuroscience of Pavlovian conditioning: a brief review

Current knowledge on the neuronal substrates of Pavlovian conditioning in animals and man is briefly reviewed. First, work on conditioning in aplysia, that has showed amplified pre-synaptic facilitation as the basic mechanism of associative learning, is summarized. Then, two exemplars of associative learning in vertebrates, fear conditioning in rodents and eyelid conditioning in rabbits, are described and research into its neuronal substrates discussed. Research showing the role of the amygdala in fear conditioning and of the cerebellum in eyelid conditioning is reviewed, both at the circuit and cellular plasticity levels. Special attention is given to the parallelism suggested by this research between the neuronal mechanisms of conditioning and the principles of formal learning theory. Finally, recent evidence showing a similar role of the amygdala and of the cerebellum in human Pavlovian conditioning is discussed.     

Role of the ventral medial prefrontal cortex in mediating behavioral control-induced reduction of later conditioned fear

A prior experience of behavioral control over a stressor interferes with subsequent Pavlovian fear conditioning, and this effect is dependent on the activation of the ventral medial prefrontal cortex (mPFCv) at the time of the initial experience with control. It is unknown whether mPFCv activity is necessary during fear learning and/or testing for this interference to occur. One week following controllable stress, the infralimbic cortex (IL) was temporarily inactivated either before fear learning or later testing. Inactivation of the IL before the test for conditioned fear, but not before conditioning, blocked the fear reducing effects of prior controllable stress. This suggests that the experience with control interferes with the expression of fear behavior and not the learning of the association, and that the mPFCv is needed to regulate conditioned fear behavior.     

Overt behavior and ultrasonic vocalization in a fear conditioning paradigm: a dose-response study in the rat

The behavioral analysis of laboratory rats is usually confined to the level of overt behavior, like locomotion, behavioral inhibition, instrumental responses, and others. Apart from such visible outcome, however, behaviorally relevant information can also be obtained when analyzing the animals' ultrasonic vocalization, which is typically emitted in highly motivational situations, like 22-kHz calls in response to acute or conditioned threat. To further investigate such vocalizations and their relationship with overt behavior, we tested male Wistar rats in a paradigm of Pavlovian fear conditioning, where a tone stimulus (CS) was preceding an aversive foot-shock (US) in a distinct environment. Importantly, the shock dose was varied between groups (0-1.1 mA), and its acute and conditioned outcome were determined. The analysis of visible behavior confirms the usefulness of immobility as a measure of fear conditioning, especially when higher shock doses were used. Rearing and grooming, on the other hand, were more useful to detect conditioned effects with lower shock levels. Ultrasonic vocalization occurred less consistently than changes in overt behavior; however, dose-response relationships were also observed during the phase of conditioning, for example, in latency, call rate and lengths, intervals between calls, and sound amplitude. Furthermore, total calling time (and rate) were highly correlated with overt behavior, namely behavioral inhibition as measured through immobility. These correlations were observed during the phase of fear conditioning, and the subsequent tests. Importantly, conditioned effects in overt behavior were observed, both, to the context and to the CS presented in this context, whereas conditioned vocalization to the context was not observed (except for one rat). In support and extent of previous results, the present data show that a detailed analysis of ultrasonic vocalization can substantially broaden and refine the spectrum of analysis in behavioral work with rats, since it can provide information about situational-, state-, and subject-dependent factors which are partly distinct from what is visible to the experimenter.     

Neural and Pavlovian influences on immunity

The traditional view that the nervous and immune systems are functionally independent (aside from general stress effects and autoimmune disorders of the nervous system) is being challenged by a new view that the nervous system regulates the activity of the immune system. If this is true, it should be possible to change the activity of the immune system by means of Pavlovian conditioning, just as it is possible to condition other physiological events influenced by the autonomic nervous system or neuroendocrine substances. Evidence for autonomic and neuroendocrine modulation of immune activity is briefly reviewed; and, the various studies reporting conditioned immune effects, the physiological mechanisms most likely involved, and their possible significance are discussed.     

Reflections on human Pavlovian decelerative heart-rate conditioning with negative tilt as US: alternative approaches.

The negative-tilt preparation that has been reported since the late seventies is a specific form of Pavlovian conditioning that is of scientific interest and has potential applications. In this paper I reflect on the usefulness, to the development of this preparation, of two approaches to Pavlovian conditioning. One approach is the older S-R learning, stimulus-substitution paradigm exemplified by learning texts of the sixties. The other is the modern, Tolman-like view, according to which the phenomenon of Pavlovian conditioning is "now described as the learning of relations among events so as to allow the organism to represent its environment." The three assumptions encapsulated by this approach are: (a) that only CS-US contingency relations are learned; (b) that teleological modes of explanations are adequate; (c) that the representational theory of knowledge is sound. Concerning Pavlovian conditioning in general, questions been raised in the literature for all three assumptions; they have not been adequately answered. Regarding the specific problem of developing the human Pavlovian heart-rate decelerative conditioning with negative tilt as the US, I suggest that the cognitive approach has been much less helpful than the older, S-R, stimulus-substitution paradigm. Nevertheless, other literature clearly indicates that the cognitive, S-S approach has generated considerable interest and research, especially in preparations like the conditioned emotional response (CER), which are CS-IR ones in the sense that the effects on the CR are assessed indirectly through measuring an indicator or instrumental response (IR).(ABSTRACT TRUNCATED AT 250 WORDS)     

条件反射性免疫抑制研究的新进展

条件反射性免疫抑制 (CIS)模式基于巴甫洛夫条件反射的机理 ,通过大脑对免疫系统进行调节 ,是一种重要的心理神经免疫学方法。近 10年来的研究取得了一些重要的进展。首先 ,条件反射性免疫抑制模型已证实是非常稳定可靠的心理神经免疫模型。其次 ,关于CIS的机制在体液、细胞、神经学方面都有广泛的研究 ,而近年来更趋向于对神经性通路的探讨。而CIS的临床应用性研究也在实验动物身上取得了稳定可靠的结果 ,证实了其未来临床应用的可行性及潜力     

Inferring danger with minimal aversive experience

Learning about threats is crucial for survival and fundamentally rests upon Pavlovian conditioning. However, Pavlovian threat learning is largely limited to detecting known (or similar) threats and involves first-hand exposure to danger, which inevitably poses a risk of harm. We discuss how individuals leverage a rich repertoire of mnemonic processes that operate largely in safety and significantly expand our ability to recognize danger beyond Pavlovian threat associations. These processes result in complementary memories – acquired individually or through social interactions – that represent potential threats and the relational structure of our environment. The interplay between these memories allows danger to be inferred rather than directly learned, thereby flexibly protecting us from potential harm in novel situations despite minimal prior aversive experience.     

The role of nucleus accumbens dopamine in outcome encoding in instrumental and Pavlovian conditioning

Considerable evidence suggests that dopamine in the core subregion of the nucleus accumbens is not only involved in Pavlovian conditioning but also supports instrumental performance. However, it is largely unknown whether NAc dopamine is required for outcome encoding which plays an important role both in Pavlovian stimulus-outcome learning and instrumental action-outcome learning. Therefore, we tested rats with 6-hydroxydopamine (6-OHDA) induced dopamine depletion of the NAc core for their sensitivity to outcome devaluation in a Pavlovian and an instrumental task. Results indicate that 6-OHDA-lesioned animals were sensitive to outcome devaluation in an instrumental task. This finding provides support to the notion that NAc core dopamine may not be crucial in encoding action-outcome associations. However, during instrumental conditioning lever pressing rates in 6-OHDA-lesioned animals were markedly lower which could reflect an impaired behavioral activation. By contrast, after outcome-specific devaluation in a Pavlovian task, performance in 6-OHDA-lesioned animals was impaired, i.e. their magazine-directed responding was non-selectively reduced. One possibility to explain non-selective responding is that NAc core DA depletion impaired the ability of conditioned stimuli to activate the memory of the current value of the reinforcer.