D-cycloserine facilitates extinction but does not eliminate renewal of the conditioned emotional response.

The effect of D-cycloserine (DCS), an NMDA partial agonist, on extinction of fear was investigated in rats using the conditioned emotional response preparation. Fear extinction was facilitated when the first 4 trials occurred with a 30-mg/kg dose of DCS. However, extinguished fear was "renewed" regardless of the drug treatment when the rats were returned to the context in which fear had been conditioned. Additional results suggest that DCS's facilitation of extinction is a small but meaningful effect in the current method. The results suggest caution regarding the use of DCS as an adjunct to extinction: Although the drug may modestly facilitate extinction learning, it does not necessarily destroy the potential for relapse. Behavioral mechanisms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The other learning process in substance abuse: Comment on Alessi, Roll, Reilly, and Johanson (2002).

The results presented in the article by S. M. Alessi, J. M. Roll, M. P. Reilly, and C.-E. Johanson (see record 2002-12827-002) suggest that the reinforcing impact of diazepam can change as a function of the participant's experience with the drug. The data fit nicely with a long tradition in learning theory that has shown the effects of reinforcers can depend crucially on what the organism has been able to learn about them. Often, that learning reflects an associative process like the one involved in Pavlovian conditioning. The hypothesis that preference for diazepam increased in the Alessi et al. study because the drug was associated with money would benefit from additional experiments that include control conditions isolating the role of the Pavlovian drug-money contingency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clustering noisy data in a reduced dimension space via multivariate regression trees

Cluster analysis is sensitive to noise variables intrinsically contained within high dimensional data sets. As the size of data sets increases, clustering techniques robust to noise variables must be identified. This investigation gauges the capabilities of recent clustering algorithms applied to two real data sets increasingly perturbed by superfluous noise variables. The recent techniques include mixture models of factor analysers and auto-associative multivariate regression trees. Statistical techniques are integrated to create two approaches useful for clustering noisy data: multivariate regression trees with principal component scores and multivariate regression trees with factor scores. The tree techniques generate the superior clustering results.     

The interdisciplinary bereavement team: defining and directing appropriate bereavement care

Hospice bereavement care often occurs in relative isolation from other program components; staff and volunteers are without the guidance, consultation and support provided through the interdisciplinary team that is enjoyed by personnel working in patient care areas. This article promotes a similar interdisciplinary team concept that has been successfully employed in one of the country's largest bereavement programs. Comprised of bereavement program staff, consultants from the patient care program, professional and lay volunteers, this interdisciplinary team defines and directs interventions provided by the bereavement care program.     

"The effects of neurotoxic hippocampal lesions on two effects of context after fear extinction": Errata.

Reports an error in the original article by R. J. Frohardt et al (Behavioral Neuroscience, 2000 [Apr], Vol 114[2], 227-240). On page 229, there is an error in the Method section. The second full sentence on that page should read: Neurotoxic lesions of hippocampus were produced by injections of a mixture of 5.0 μg ibotenic acid and 5.0 μg NMDA per 0.5 ml of normal saline. (The following abstract of this article originally appeared in record 2000-15286-001): Three conditioned suppression experiments with rats examined the role of the hippocampus in 2 effects of context after extinction. Reinstatement is the context-specific recovery of fear to an extinguished conditioned stimulus (CS) that occurs following independent presentations of the unconditioned stimulus (UCS), after extinction. Renewal is the recovery of fear when the CS is presented in the context in which it was conditioned, after extinction in a different context. Results indicated that neurotoxic lesions of the hippocampus, performed before conditioning, abolished reinstatement, which depends on context-UCS associations, but not renewal, which does not. This dissociation is not the result of differences in the recentness of context learning that ordinarily governs the two effects… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the rat hippocampal system in several effects of context in extinction.

The effect of fornix lesions on some effects of manipulating the context on performance in extinction were studied. In renewal, subjects' responding to an extinguished CS recovered when the CS was presented in the context in which it had been conditioned after extinction in a different context. In reinstatement, it recovered when the CS was tested after independent presentation of the unconditioned stimulus (UCS; an effect mediated by contextual conditioning.) In spontaneous recovery, it recovered after the passage of time, that is, when the CS was tested in a new temporal context. In the conditioned suppression method, fornix lesions had no effect on conditioning, extinction, renewal, or spontaneous recovery; however, they abolished the reinstatement effect. The results suggest that the hippocampal system may be important in the formation of context–UCS associations, but not in other types of learning about the context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual control of the extinction of conditioned fear: Tests for the associative value of the context.

When male Wistar rats received pairings of a CS with shock in one context and then extinction of the CS in another, fear of the CS was renewed when the CS was returned to and tested in the original context (Exps I and III; 40 Ss). No such renewal was obtained when the CS was tested in a 2nd context after extinction had occurred in the conditioning context (Exp IV; 24 Ss). In Exp II, shocks presented following extinction reinstated fear of the CS, but only if they were presented in the context in which the CS was tested. In each experiment, the associative properties of the contexts were independently assessed. Contextual excitation was assessed primarily with context-preference tests in which Ss chose to sit in either the target context or an adjoining side compartment. Contextual inhibition was assessed with summation tests. Although reinstatement was correlated with demonstrable contextual excitation present during testing, the renewal effect was not. There was no evidence that contextual inhibition developed during extinction. Results suggest that fear of an extinguished CS can be affected by the excitatory strength of the context but that independently demonstrable contextual excitation or inhibition is not necessary for contexts to control that fear. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time and context effects on performance in a Pavlovian discrimination reversal.

Five conditioned suppression experiments with rats explored retention interval and context effects in discrimination reversal learning. In the discrimination phase, a tone (T) was paired with shock, and a houselight-off stimulus (L) was presented alone; in the reversal phase, T was extinguished and L was paired with shock. Discrimination training made L a latent inhibitor but not a conditioned inhibitor. A 28-day delay after the reversal caused spontaneous recovery to T but had no effect on L. A context switch before the reversal caused more rapid conditioning to L but did not affect extinction to T. A return to the original context after the reversal had occurred in a different context renewed suppression to T and latent inhibition to L; contextual control was strong 21 days later. Tests in a neutral context indicated that each training context controlled performance to T and L. A memory retrieval framework may begin to integrate the effects of context and time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning, remembering, and forgetting.

Argues that the separation of theories of learning and of memory should be abandoned. Remembering and forgetting play an important role in simple conditioning experiments. For example, conditioned performance can readily recover after extinction because extinction is susceptible to forgetting. Memory itself involves the kind of associative learning that conditioning experiments are designed to investigate (e.g., conditioning experiments provide insight into the mechanisms of memory retrieval). Learning, remembering, and forgetting all occur within the same biological context; their adaptive functions are therefore intertwined. Taken together, they shed light on some of the mechanisms of clinical relapse. Conditioning theory enriches, and is enriched by, the field of memory as well as other fields of behavioral science. (PsycINFO Database Record (c) 2010 APA, all rights reserved)