Transient effects of reward presentation and omisision on subsequent operant responding.

In 3 experiments a total of 12 male Lister hooded rats were run in a 2-component operant analog of the double runway in which the frequency of reward in the 1st component was varied over 0, 50, and 100%. Responding in the 2nd component was measured after either a long (60-sec) or short (3-sec) intercomponent interval (ICI). After the short ICI, 2nd-component responding was faster following nonreward than reward, while the preceding goal event had no effect after the long ICI. A comparison of performance after long and short ICIs showed that the difference at short ICIs was due solely to the depressive effects of reward which persisted well into the instrumental response sequence. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal damage does not impair instrumental appetitive conditioning with delayed reinforcement

The present study evaluated the effects of bilateral hippocampal lesions on appetitive instrumental conditioning with delayed (5-s interval) reinforcement in rats. Acquisition of a bar press response was considerably slower than rates observed with immediate reinforcement; however, no significant differences between hippocampally lesioned and control groups were noted regarding training to criteria or ratio of responses to reinforcements. These results suggest that the hippocampus is not essential for the association of temporally discontinuous stimuli, and that deficits in other forms of associative learning, such as spatial cognition, must be mediated by the loss of other functions. Putative functions and underlying substrates are discussed for response modulation and sensory (cue relations) associations.     

Adrenal responses to reinforcement and extinction: Role of expectancy versus instrumental responding.

Measured plasma corticosterone levels during operant conditioning to determine the effect of reinforced and nonreinforced responding (extinction) on adrenal activation; Ss were 44 male Long-Evans rats. The influence of instrumental responding was assessed by comparing trained Ss with yoked Ss that received a matched reward schedule in the absence of an operant task. Reinforcement sessions resulted in a significant decrease in adrenal secretion at 20 min but not at 5 min, whereas extinction caused a rapid increase in corticosterone levels at 5 min and an even greater elevation at 20 min. Comparison of the operant and yoked Ss showed that this effect of reinforcement and extinction was not dependent on instrumental responding, but rather on the receipt or withdrawal of the expected reward. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context specificity of conditioning, extinction, and latent inhibition.

Three experiments, using a conditioned suppression procedure with 112 male hooded Lister rats, examined the mechanisms of context specificity of conditioning, extinction, and latent inhibition. Exp I replicated previous demonstrations of context specificity of conditioning and extinction. Conditioning in one context did not necessarily transfer perfectly to another, and if extinction was carried out in a context different from that of conditioning, Ss showed a recovery of suppression when tested in the conditioning context. But both of these results disappeared when the familiarity and associative values of the 2 contexts were equated. Exp II replicated this failure to obtain context specificity of conditioning and extinction, but it did obtain context specificity of latent inhibition. Ss preexposed and conditioned to stimuli in the same context showed more profound latent inhibition than those preexposed and conditioned in different contexts. In Exp III, this effect was replicated. It is concluded that context specificity of conditioning or extinction may arise from the failure to control the associative status of the contexts used, whereas that of latent inhibition can best be explained by A. R. Wagner's (1976, 1981) theory of associative learning. Results offer no support for the view that, under conditions such as these, contexts serve as conditional cues, signaling the relationships between events occurring in their presence. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A taxonomy of instrumental conditioning.

Proposes a classification scheme for instrumental conditioning paradigms based on 4 dichotomies: (a) whether the organism is required to "emit" or "omit" a response, (b) whether a "desirable" or "aversive" stimulus event is made contingent upon the response, (c) whether the operation performed upon this stimulus event is one which "increases" or "decreases" its magnitude or intensity, and (d) whether or not the organism is given any "signal" prior to the response as to the consequent stimulus event. The resulting classification scheme includes 16 distinct paradigms, each of which is illustrated with research examples (when they are known to exist) and with examples from "real-life" situations. The relationship between the present scheme and previous classification attempts is indicated, and a meaningful and consistent nomenclature is proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

mGluR5 positive allosteric modulation enhances extinction learning following cocaine self-administration.

Extinction of classically and instrumentally conditioned behaviors, such as conditioned fear and drug-seeking behavior, is a process of active learning, and recent studies indicate that potentiation of glutamatergic transmission facilitates extinction learning. In this study, the authors investigated the effects of the Type-5 metabotropic glutamate receptors (mGluR5) positive allosteric modulator 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) on the extinction of cocaine-seeking behavior in rats with a history of intravenous cocaine self-administration. To assess its effects on acquisition and consolidation of extinction learning, CDPPB (60 mg/kg) or vehicle was administered either 20 min prior to, or immediately following, each of 10 extinction sessions, respectively. When administered prior to each extinction session, CDPPB produced a significant reduction in the number of active lever presses on all 10 days of extinction training as compared to vehicle-treated animals. When administered following each extinction session, a significant reduction in the number of active lever presses was observed on the 2nd through 10th day of extinction. Both treatment regimens also reduced the number of extinction-training sessions required to meet extinction criteria. Pre- or postextinction-training administration of CDPPB did not alter responding on the inactive lever and had no effects on open field locomotor activity. These data indicate that positive allosteric modulation of mGluR5 receptors facilitates the acquisition and consolidation of extinction learning following cocaine self-administration and may provide a novel pharmacological approach to enhancing extinction learning when combined with cue exposure therapy for the treatment of cocaine addiction. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Slow reacquisition following extinction: Context, encoding, and retrieval mechanisms.

Investigated the slow reacquisition (RAQ) of responding in rats that occurs when the conditioned stimulus/stimuli (CS) and unconditioned stimulus/stimuli (UCS) are paired again after prolonged extinction training. In Exp 1, an extinguished CS acquired less suppression than a novel CS during a final conditioning phase, but more suppression than CSs that had received comparable nonreinforcement without initial conditioning. In Exp 2, CS–UCS pairings resumed in the context of extinction caused the least RAQ of suppression: Pairings in a neutral context produced better RAQ, while return of the CS to the conditioning context caused an immediate renewal of responding to the CS. In Exp 3, a return of the CS to the extinction context after RAQ training caused renewed extinction performance and interfered with performance appropriate to RAQ. This effect was not due to demonstrable inhibitory conditioning of the extinction context. Results suggest that representations of conditioning and extinction (or CS–UCS and CS–no UCS relations) are both retained through extinction and that performance appropriate to either phase can be cued by the corresponding context. RAQ may thus be slow when the context retrieves an extinction memory. Similar mechanisms may also play a role in other Pavlovian interference paradigms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robust-single-trial delayed backward conditioning.

80 female albino rats, shocked once while eating in the presence of a novel stimulus panel, were exposed to a complex stimulus object after a blackout period of 1-40 sec. 40 other Ss served as controls. The next day Ss were observed in a test for differential avoidance of the shock location, the forward-order conditioned stimulus (CS) and the backward-order CS. On the basis of 5 different classes of behavior, Ss in the 1-, 5-, and 10-sec blackout groups avoided the backward-order CS rather than the shock location or the forward-order CS. The association does not appear to be based primarily on temporal sequence or the signaling relationship involved in Pavlovian conditioning. Instead, it appears that the association is dependent on the specific nature of the stimuli, possibly reflecting an evolved learning capability for associating noxious exteroceptive stimuli with predatorlike objects. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resistance to extinction in evaluative conditioning.

A well-demonstrated phenomenon in traditional Pavlovian conditioning research with humans is that of experimental extinction. In contrast, human evaluative conditioning research suggests that evaluative learning shows marked resistance to extinction. Here, the authors replicate both findings concurrently. Two differential fear conditioning experiments with an electrocutaneous stimulus as the unconditioned stimulus evidenced (a) sensitivity to extinction using an autonomic skin-conductance measure and (b) complete resistance to extinction using an affective-priming measure. The results corroborate the idea that evaluative conditioning is more resistant to extinction than is expectancy learning (F. Baeyens, P. Eelen, & G. Crombez, 1995). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The dynamics of conditioning and extinction.

Pigeons responded to intermittently reinforced classical conditioning trials with erratic bouts of responding to the conditioned stimulus. Responding depended on whether the prior trial contained a peck, food, or both. A linear persistence–learning model moved pigeons into and out of a response state, and a Weibull distribution for number of within-trial responses governed in-state pecking. Variations of trial and intertrial durations caused correlated changes in rate and probability of responding and in model parameters. A novel prediction—in the protracted absence of food, response rates can plateau above zero—was validated. The model predicted smooth acquisition functions when instantiated with the probability of food but a more accurate jagged learning curve when instantiated with trial-to-trial records of reinforcement. The Skinnerian parameter was dominant only when food could be accelerated or delayed by pecking. These experiments provide a framework for trial-by-trial accounts of conditioning and extinction that increases the information available from the data, permitting such accounts to comment more definitively on complex contemporary models of momentum and conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postconditioning devaluation of a reinforcer affects instrumental responding.

Three experiments with 68 male Holtzman rats investigated performance of an instrumental response following postlearning changes in the value of the reinforcer, using a within-S design. Exps I and II used a conditioning manipulation (pairing with a toxin), and Exp III employed a motivational procedure (satiation) to reduce the reinforcer value. In both cases, performance of the instrumental response was substantially attenuated during a subsequent extinction test. Results suggest that these devaluation effects are mediated by the instrumental contingency and that a reasonably detailed representation of the reinforcer is encoded in instrumental learning. (38 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Concerning instrumental autonomic conditioning: A rejoinder.

A. Crider, G. Schwartz, and S. Shnidman's (see 43:8) reply to E. S. Katkin and E. N. Murray's (see 42:10) review of instrumental autonomic conditioning makes several valid points but also contains many differences in interpretation based on a contrasting theoretical position. It is contended herein that the acceptability of "facts" as "facts" and "evidence" as "evidence" is determined often by predisposing epistemological orientations. Many of Crider et al.'s points are well taken, but the evidence on instrumental autonomic conditioning in humans remains far less convincing than the evidence available from animal studies. The methodological questions raised by Katkin and Murray's earlier paper appear to be clarified substantially by some of Crider et al.'s comments; however, the clarification has not reduced the danger of artifacts being interpreted as substantive evidence. (30 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus–response overshadowing: Effects of signaled reward on instrumental responding as measured by response rate and resistance to change.

If every food reinforcer delivered on a VI schedule is preceded by a brief flash of light, rats leverpress for food more slowly than if light flashes are given independent of the food and their responding. This retardation in rate has been attributed to the overshadowing of the response–food association by the light–food association. Such an explanation assumes that response rate is positively correlated to the response association strength. Exps I and II investigated this account by using prefeeding and extinction procedures to test the strength of responding in 44 Long-Evans rats that had received food-correlated or random-light signals. Acquisition response rate was lower in the signaled condition (consistent with previous studies), but responding was more resistant to both extinction and satiation, regardless of whether the light cues were presented during the extinction/prefeeding phase. Exp III, with 27 Ss, revealed no difference between the signaled and random conditions either in terms of acquisition response rates or resistance to satiation when a VR schedule of reinforcement was used. Results are inconsistent with an overshadowing account of the acquisition rate difference. Instead, the signal seems to enhance the rat's sensitivity to the contingencies present on VI schedules. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shock-induced suppression and potentiation of instrumental responding by rats.

A total of 20 female Long-Evans rats trained to press a retractable lever for food in a discrete trials situation were subsequently punished for responding. After suppression of responding, response-independent shocks were presented, with intensity increased on successive daily sessions. Shock induced responding, and number of responses, increased and response latencies decreased with increasing shock intensity. Control Ss initially given uncorrelated lever-food presentations responded significantly less to response-independent shock, and their responding was not systematically related to shock intensity. Results are consistent with the view that shock induces or disinhibits prepotent responses and inconsistent with the view that, to be effective in suppressing behavior, punishment must induce responses incompatible with the punished response. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The pedunculopontine tegmental nucleus and responding for sucrose reward.

Pedunculopontine tegmental nucleus (PPTg) lesions in rodents lead to increased sucrose consumption, but the psychological deficit behind this remains uncertain. To understand better the relationship between consumption of, and motivation for, sucrose, the authors trained rats to traverse a runway for 20% or 4% sucrose solution; after 7 days, concentrations were reversed. Control rats consumed more 20% than 4% sucrose solution and promptly altered run times in response to concentration change. PPTg-lesioned rats consumed normal quantities of 4% but more 20% sucrose solution than controls and took longer to alter their runway time following the concentration change. These data suggest that lesions of the PPTg do not alter motivation per se and might be better understood as inducing a response selection deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anticipated reward enhances offline learning during sleep.

Sleep is known to promote the consolidation of motor memories. In everyday life, typically more than 1 isolated motor skill is acquired at a time, and this possibly gives rise to interference during consolidation. Here, it is shown that reward expectancy determines the amount of sleep-dependent memory consolidation. Subjects were trained on 2 different sequences of a finger sequence motor task before 12-hr retention intervals of either nocturnal sleep or daytime wakefulness. After training was finished, reward expectancy was varied by announcing a monetary reward for performance improvement at retesting on either the first- or second-trained sequence. Before the retest, however, subjects were informed that reward would depend not on only 1 sequence but on the average performance for both sequences. Posttraining sleep enhanced overall finger sequence performance. The sleep-dependent gain in skill was significantly greater for the sequence that was associated with monetary reward after training, regardless of whether this sequence was the first or second to be trained. After wake retention intervals, no or only minor performance gains were observed. The data show that expectancy for a reward enhances offline learning of a skill during sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual control over conditioned responding in an extinction paradigm.

Four experiments studied contextual control over rats' freezing to conditioned stimuli (CSs) that had been paired with shock and were then extinguished. In Experiment 1, rats were exposed to a CS A–shock and a CS B–shock pairing in Context C. CS A was then extinguished in Context A, and CS B in Context B. Freezing was renewed when each CS was presented in the context where the other CS had been extinguished. In Experiments 2–4, rats were exposed to a CS A–shock pairing in A and a CS B–shock pairing in B. They were then exposed to Context C where one, both, or neither of the CSs were extinguished, or where both CSs continued to be reinforced. On test, the rats froze more to CS A than to CS B in Context A, and more to CS B than to CS A in Context B, but only if the CSs had been extinguished. Thus, after extinction, rats use contexts to regulate retrieval not only of their memory for extinction, but also of their memory for the original conditioning episode. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Picrotoxin enhances latent extinction of conditioned fear.

Male CD1 mice received 20 pairings of tone and footshock (FS) or tone alone in an arm of a Y-maze on Day 1. On Day 2 either extinction (tone alone) or no extinction was followed immediately by saline or picrotoxin (0.5 or 1.0 mg/kg ip). Nonextinguished groups received only saline or picrotoxin (1.0 mg/kg ip) on Day 2. Other groups received saline or picrotoxin (1.0 mg/kg) 2 hr after extinction. On Day 3 all mice were placed in the Y-maze (with doors to all 3 alleys open), and total alley entries during a 2-min test session were recorded. Day 1 FS training resulted in reduced alley entries during the test session. Day 2 extinction session significantly attenuated the effects of the FS training. Day 3 performance of mice given picrotoxin (1.0 but not 0.5 mg/kg) immediately postextinction was comparable to that of mice not given FS on Day 1. The findings suggest that picrotoxin enhanced extinction of conditioned fear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interocular transfer of conditioning and extinction in birds.

Conditioned 6 chickens, 6 pigeons, and 5 ring-billed gulls, all with 1 eye covered, to withdraw from a previously neutral visual stimulus. Subsequent testing with the trained eye covered and the control eye open showed that transfer or nontransfer of conditioning was a function of the particular aversive stimulus used in conditioning; that is, transfer resulted when shock was used as the UCS but did not occur when the UCS was a rapidly looming visual stimulus or a loud noise. However, when both eyes of an S had been exposed to the conditioning procedure and then the response extinguished by repeatedly presenting the conditioned stimulus to 1 eye only, the conditioned response remained strong for the control eye regardless of the UCS used in the initial training. These findings were consistent regardless of the order of treatments, and no substantive differences among the 3 species were apparent. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)