Extinction Of Pavlovian Conditioning Research Articles

Pavlovian conditioning achieved via one-transistor/one-resistor memristive synapse

Mimicking Pavlovian conditioning by memristive synapse is significant to implement neuromorphic computing at the hardware level. In this work, we demonstrated the Pavlovian conditioning based on the artificial synapse architecture of one-transistor/one-resistor (1T1R), which included an AgInSbTe/α-C-based memristor as a variable resistance and an N-MOS transistor. Thanks to stable resistance switching behavior of memristor and outstanding controllability of device conductance by transistor gating of 1T1R, the experimental demonstration of the acquisition and extinction of Pavlovian conditioning were realized. Moreover, the temporal relation between the conditioned and unconditioned stimuli was also established in which the memory time of associative learning decreased with the increase in the interval of two stimuli. This work provided an idea to biorealistically mimic the Pavlovian conditioning, paving the way for memristive neuromorphic computing.

Interplay of prefrontal cortex and amygdala during extinction of drug seeking

Extinction of Pavlovian conditioning is a complex process that involves brain regions such as the medial prefrontal cortex (mPFC), the amygdala and the locus coeruleus. In particular, noradrenaline (NA) coming from the locus coeruleus has been recently shown to play a different role in two subregions of the mPFC, the prelimbic (PL) and the infralimbic (IL) regions. How these regions interact in conditioning and subsequent extinction is an open issue. We studied these processes using two approaches: computational modelling and NA manipulation in a conditioned place preference paradigm (CPP) in mice. In the computational model, NA in PL and IL causes inputs arriving to these regions to be amplified, thus allowing them to modulate learning processes in amygdala. The model reproduces results from studies involving depletion of NA from PL, IL, or both in CPP. In addition, we simulated new experiments of NA manipulations in mPFC, making predictions on the possible results. We searched the parameters of the model and tested the robustness of the predictions by performing a sensitivity analysis. We also present an empirical experiment where, in accord with the model, a double depletion of NA from both PL and IL in CPP with amphetamine impairs extinction. Overall the proposed model, supported by anatomical, physiological, and behavioural data, explains the differential role of NA in PL and IL and opens up the possibility to understand extinction mechanisms more in depth and hence to aid the development of treatments for disorders such as addiction.

Time, trials, and extinction.

Four experiments investigated the effect of number of trials and total duration of nonreinforced exposure to the conditioned stimulus (CS) on extinction of Pavlovian conditioning. Rats were first trained in a magazine approach paradigm with multiple CSs, each paired with the unconditioned stimulus (US) on a variable CS-US interval. During subsequent extinction, CSs would differ in the number and length of their extinction trials but would be matched for the total duration of exposure (e.g., 1 CS would have 20 trials per session with a mean length of 5 s; another CS would have 5 trials per session with a mean length of 20 s). In each case, extinction proceeded more quickly for the CS given more trials per session. Indeed, there was no difference in rate of extinction between CSs that were matched on number of trials but differed on the duration of each trial, indicating that duration of exposure has no effect on extinction. We discuss the implications of these findings for trial-based and time-based theories of conditioning. (PsycINFO Database Record

Experimental extinction in Pavlovian conditioning: behavioural and neuroscience perspectives.

This paper reviews the behavioural and neuroscience literatures on extinction in Pavlovian conditioning with a view towards finding possible points of contact between these two often independent lines of investigation. Recent discoveries at the behavioural level indicate (1) that conditioned stimulus (CS)-unconditioned stimulus (US) associations specific in their sensory content are fully preserved during extinction, (2) that inhibitory stimulus-response associations appear to be learned during extinction, (3) that extinction is influenced by the level of activation of the US representation during nonreinforced trials, (4) that decreases in attention can influence conditioned performance during extinction, and (5) that contexts acquire an ability to modulate learning during both conditioning and extinction. Recent discoveries at the neural systems level suggest (1) that the hippocampus is important in context-specific learning during extinction, (2) that the prefrontal cortex is possibly important in long-term memory for extinction, (3) that the basolateral amygdala may be important in sustaining attention to a CS during extinction, (4) that NMDA receptors are important either in neural plasticity during extinction or by affecting the value of the US representation during extinction, and (5) that the GABAergic system may partially mediate inhibitory learning during extinction. It is concluded that both of these levels of analysis can benefit the other in the pursuit of a more comprehensive understanding of extinction.

Extinction, renewal, and spontaneous recovery of a spatial preference in the water maze.

Four experiments with C57BL/6 mice investigated extinction of a spatial preference in the Morris water maze. In Experiment 1, a spatial preference was extinguished by exposing mice to the water maze in the absence of a platform but in the presence of the distal spatial cues. In Experiment 2, extinction occurred when the platform was removed from the pool, when it was presented in random locations, or when it was presented consistently in the opposite location. Contextual renewal (Experiment 3) and spontaneous recovery (Experiment 4) of spatial preferences argue against an interpretation of extinction in terms of unlearning and instead suggest that extinction in the water maze, like extinction in Pavlovian conditioning, suppresses the original association. Implications of these findings for theories of spatial learning and hippocampal function are discussed.

Conducting exposure treatment in multiple contexts can prevent relapse

The acquisition of anxiety disorders (e.g., phobias) is often thought to be mediated by classical conditioning processes (e.g., Wolpe, 1958, Psychotherapy by reciprocal inhibition Wolpe and Rowan, 1989, Behaviour Research and Therapy, 27, 583–585). Thus, the success of exposure therapy is possibly a consequence of extinction, and factors affecting extinction in Pavlovian conditioning are potentially relevant to clinicians who administer exposure therapy. The present experiments investigated the effects of conducting extinction in multiple contexts using rats as subjects in a conditioned suppression paradigm. In Experiment 1, subjects received conditioned stimulus (CS) and unconditioned stimulus (US) pairings in one context followed by extinction of that CS in one or three other contexts. When tested in an associatively neutral context (i.e., different from those of conditioning or extinction), rats that had received extinction in three contexts exhibited less responding to the CS than rats that had received extinction in one context. In Experiment 2, CS–US training occurred in either one or three contexts, followed by extinction of that CS in three other contexts. Testing in a neutral context revealed that rats conditioned in multiple contexts showed greater responding to the CS than rats trained in a single context. The results are discussed in the framework of memory retrieval, and the clinical implications are explored.

The secret of successful defense.

The demise of stimulus-response behaviorism has brought radical changes in the way psychologists conceptualize classical Pavlovian conditioning, as described by Rescorla (1988). The new emphasis on learned expectations sheds light on Freud's 1926 theory of intrapsychic conflict which explains neurotic anxiety by the same principles that account for realistic anxiety. Learned expectations also figure prominently in the recent writings of a number of psychoanalytic theorists. This paper uses these principles to explain "successful defense," which is customarily defined as the activation of defense in the absence of conscious anxiety. These same principles elucidate an important difference between the therapeutic mechanisms of supportive versus expressive psychotherapy. This distinction parallels the difference between conditioned inhibition versus extinction in Pavlovian conditioning.

Naloxone induces multiple effects on aversive Pavlovian conditioning in rabbits.

A series of experiments examined the effects of intravenous naloxone treatment on aversive Pavlovian conditioning of eye-blink and heart rate responses, and related unconditioned behaviors, in rabbits. Naloxone treatment before testing attenuated bradycardiac orienting responses to tones used as conditioning stimuli. Naloxone also attenuated conditioned bradycardia when administered either before or after training sessions, but it potentiated conditioned bradycardia during extinction of discriminative conditioning. Naloxone did not influence acquisition or extinction of discriminative eye-blink conditioning or somatic or cardiac responses to shocks used as unconditioned stimuli, but it did decrease locomotor activity. Naloxone treatment immediately after training sessions facilitated acquisition of eye-blink responses. It was concluded that naloxone influences aversive Pavlovian conditioning in more than one way: (a) During training, it appears to alter reception and processing of signals but does not affect subsequent development of somatic responses to the Pavlovian conditioning contingency. (b) After training sessions, naloxone apparently affects consolidation of both somatic and autonomic conditioning. (c) Naloxone also appears to delay extinction of Pavlovian conditioning; this effect may similarly involve changes in a stimulus-processing mechanism or in memory functions, but it apparently does not involve changes in somatomotor responsitivity.