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

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 2 effects. The results suggest that the hippocampus is necessary for some, but not all, types of contextual learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"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 effect of yohimbine on the extinction of conditioned fear: A role for context.

Six experiments with rat subjects examined the effect of yohimbine, an alpha-2 adrenergic autoreceptor antagonist, on the extinction of conditioned fear to a tone. Experiments 1 and 2 demonstrated that systemic administration of yohimbine (1.0 mg/kg) facilitated a long-term decrease in freezing after extinction, and this depended on pairing drug administration with extinction training. However, Experiments 3 and 4 demonstrated that yohimbine did not eradicate the original fear learning: Freezing was renewed when the tone was tested outside of the extinction context. Experiments 5 and 6 found that the contextually specific attenuation of fear produced by yohimbine transferred to another extinguished conditional stimulus (CS) and not to a nonextinguished CS. The results suggest that yohimbine, when administered in the presence of a neutral context, creates a form of inhibition in that context that allows that specific context to reduce fear of an extinguished CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of hippocampal stimulation on acquisition, extinction, and generalization of conditioned suppression in the rat.

In 6 experiments, a total of 142 male Holtzman rats implanted with electrodes in the dorsal or ventral hippocampus received posttrial stimulation in training sessions with footshock reinforcement. Afterdischarges without overt seizures were consistently without effect on the rate of acquisition of suppression of licking during an auditory CS, although conditioning was retarded by the delivery of distracting stimuli following footshock. The rate of conditioning remained insensitive to elicitation of dorsal hippocampal afterdischarges (DHAD) despite subsequent alterations of session length, intertrial interval, and preexposure to the CS. However, faster extinction of suppression occurred following DHAD, suggesting a limited but essential role of the hippocampus in addressing stored information. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Convergence of sensory input on units in the hippocampal system of the rat.

Recorded unit responses to auditory and visual stimuli from chronically implanted electrodes in the limbic system of 22 albino male Holtzman rats. The stimuli were presented first in a random order and later in a classical sensory conditioning paradigm in which a flash of light followed a tone. Short latency unit responses to both light and tone were found in the medial septum and the cingulate cortex. The conditioning paradigm did not cause significant changes in the firing rates of nonresponding units and did not significantly change existing responses. Only small transient changes were noticed in CA1 hippocampal units. It is concluded that sensory responses could be detected in the hippocampus and its afferents, but a classical sensory paradigm is not an efficient way to enhance hippocampal responsiveness to neutral stimuli. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the shared family context in differential parenting.

This article examines the role of the shared family context in understanding differential parental treatment of children. Child-specific and family-context predictors of differential parental positivity and negativity were examined using multilevel modeling in a population of 8,476 children nested in 3,762 families. Child age was the strongest child-specific predictor of positivity and differential positivity. Lower socioeconomic status (SES), marital dissatisfaction, and larger family size were associated with higher levels of differential positivity. There was evidence of potentiation when risks were combined. Children's temperament was associated with parental negativity and differential negativity. The strength of this association was moderated by SES. Mixed-gender sibships in families with marital dissatisfaction and children in single-parent families received the highest levels of differential negativity. The findings are discussed in the context of shared and nonshared environmental influences on development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The interactive effects of type of deprivation and sucrose concentration on the acquisition and extinction performance in the rat.

In a discrete-operant barpress situation with 128 female albino Sprague-Dawley rats, 4 types of deprivation (food, water, water plus food, and no deprivation) were combined factorially with 4 levels of reward (0, 4, 16, and 64% sucrose concentration). In acquisition, water (0% sucrose) served as an effective reinforcer only when Ss were deprived of water alone. Higher sucrose concentrations tended to produce correspondingly higher levels of performance when food, water plus food, and no deprivation were used. No such differences were obtained with water deprivation. Resistance to extinction was an increasing function of sucrose concentration when Ss were deprived of food and water plus food. No differences were observed under the other 2 deprivation conditions. (French summary) (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparisons of behavioral effects of hippocampal and prefrontal cortex lesions in the rat.

5 groups of 5 male Wistar rats each, with aspiration lesions of dorsomedial frontal cortex, ventrolateral frontal cortex, hippocampus, or posterior cortex, or with sham operations, were tested in 5 behavioral situations: emotionality assessment, serial spatial reversals, 70:30 spatial probability, differential reinforcement of low rates (DRL), and barpress extinction. Ss with posterocortical lesions did not differ from operated controls on any task. The effects of lesions in the 2 anatomically defined frontal subfields were clearly dissociated on spatial reversals, spatial probability, and DRL. Lesions in either subfield produced a significant increase in emotionality relative to controls, and neither lesion affected barpress extinction. Results suggest that both frontal subfields may be functionally related to the hippocampus but in different ways. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of hippocampal ablations on dispositional and representational memory in the rat.

Long-Evans rats with electrolytic hippocampal ablations exhibited chronic impairment in performance on a spatial delayed nonmatching-to-sample task in the arms of a T-maze. The same rats exhibited only mild deficits, which disappeared with practice, in dispositional memory-dependent discrimination in the stem. Both types of discrimination were learned rapidly preoperatively with no marked positive or negative interaction between types of discrimination. The present results suggest that hippocampal lesions in rats have far more serious consequences on the performance of representational memory-dependent tasks than similar lesions in monkeys. In agreement with our past studies, the present experiment demonstrated that dispositional and representational memory systems in rodents have at least partially distinct anatomical substrates in brain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned effects of kindling three different sites in the hippocampal complex of the rat.

Rats received kindling stimulations to the perirhinal cortex (PRh), ventral hippocampus (VH), or dorsal hippocampus (DH) in 1 environment and an equivalent number of sham stimulations in a 2nd environment. The PRh-kindled rats displayed rapid kindling and a swift emergence of conditioned interictal defensiveness. In contrast, the VH- and DH-kindled rats displayed much slower kindling and slow or no conditioning, respectively. No effects of conditioning on the convulsions, comparable with those associated with amygdala kindling, were observed. These results establish the generality of some of the previously reported kindling-related conditioned effects, confirm the site specificity of some of these effects, and suggest that the convulsions, rather than the stimulations, function as the unconditioned stimuli for the conditioning of interictal behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neurotoxic effects of sodium nitroprusside in rat hippocampal slices

The effect of a permanent transection on myelin gene expression in a regenerating sciatic nerve and in an adult sciatic nerve was compared to establish the degree of axonal control exerted upon Schwann cells in each population. First, the adult sciatic nerve was crushed, and the distal segment allowed to regenerate. At 12 days post-crush, the sciatic nerve was transected distal to the site of crush to disrupt the Schwann cell-axonal contacts that had reformed. Messenger RNA (mRNA) levels coding for five myelin proteins were assayed in the distal segment of the crush-transected nerve after 9 days and were compared to corresponding levels in the distal segments of sciatic nerves at 21 days post-crush and 21 days post-transection using Northern blot and slot-blot analysis. Levels of mRNAs found in the distal segment of the transected and crush-transected nerve suggested that Schwann cells in the regenerating nerve and in the mature adult nerve are equally responsive to axonal influences. The crush-transected model allowed the genes that were studied to be classified according to their response to Schwann cell-axonal contact. The levels of mRNAs were 1) down-regulated to basal levels (P0 and MBP mRNAs), 2) down-regulated to undetectable levels (myelin-associated glycoprotein mRNAs), 3) upregulated (mRNAs encoding 2'3'-cyclic nucleotide phosphodiesterase and beta-actin), or 4) not stringently controlled by the removal of Schwann cell-axonal contact (proteolipid protein mRNAs). This novel experimental model has thus provided evidence that the expression of some of the important myelin genes during peripheral nerve regeneration is dependent on continuous signals from the ingrowing axons.     

The effect of differential hippocampal lesions and pre- and postoperative training on extinction.

Examined resistance to extinction of a food-motivated response in a total of 78 male albino Wistar rats with sham operations or bilateral dorsal hippocampal, ventral hippocampal, or combined dorsal and ventral hippocampal lesions in 2 experiments. Surgery occurred either before or after acquisition of the to-be-extinguished response. Ss with combined hippocampal lesions showed greater resistance to extinction than controls if acquisition occurred preoperatively, but less resistance if acquisition occurred postoperatively. Ss with ventral hippocampal lesions were affected in a similar manner but to a lesser degree by differential prior experience. In contrast, dorsal hippocampal-lesioned Ss exhibited no change in approach latency during extinction, irrespective of the timing of surgery. It is suggested that both ventral and combined hippocampal lesions interfere with the changing of an established approach "set." (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of a context shift and multiple context extinction on reactivity to alcohol cues.

Cue exposure treatment (CET) attempts to reduce the influence of conditioned substance cues on addictive behavior via extinction, but has received only modest empirical support in clinical trials. This may be because extinction learning appears to be context dependent and a change in context may result in a return of conditioned responding (i.e., renewal), although this has received only limited empirical examination. The current study used a 4-session laboratory analogue of CET to examine whether a change in context following 3 sessions of alcohol cue exposure with response prevention would result in renewal of conditioned responding. In addition, this study examined whether conducting extinction in multiple contexts would attenuate renewal of conditioned responding. In one-way between-subjects design, 73 heavy drinkers (71% men) were randomized to 3 conditions: (a) single context extinction (extinction to alcohol cues in the same context for 3 sessions followed by a context shift at the fourth session), (b) multiple context extinction (extinction to alcohol cues in different contexts each day for all 4 sessions), and (c) pseudoextinction control condition (exposure to neutral cues in the same context for 3 sessions followed by exposure to alcohol cues at the fourth session). The results revealed the predicted cue reactivity and extinction effects, but the hypotheses that a context shift would generate renewed cue reactivity and that multiple contexts would enhance extinction were not supported. Methodological aspects of the study and the need for parametric data on the context dependency of extinction to alcohol cues are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of context in re-acquisition of extinguished alcoholic beer-seeking.

We studied the role of context in reacquisition of extinguished reward-seeking. Rats were trained to respond for alcoholic beer, then extinguished and retrained. Reacquisition was faster than acquisition regardless of whether retraining occurred in the original training context, the extinction context, a novel context, or a context with a mixed history of reinforcement. Reacquisition was also rapid after extended extinction training. Nonetheless, context did significantly influence reacquisition via affecting latency to first response: rats took significantly longer to initiate responding when tested in the extinction context. These results suggest that reacquisition of drug and reward seeking is determined by an inhibitory influence caused by the extinction context and a facilitatory influence caused by reintroduction of the reinforcer (Bouton, 1993). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Instructions and the extinction of a learned fear in the context of taped implosive therapy.

Gave 58 female undergraduates who were afraid of snakes taped implosive therapy preceded by no instructions or 1 of 3 possible instructional sets: (a) suggestion that the tapes would help them overcome their snake fear, (b) an explanation of the theoretical basis of the procedure they were about to undergo, and (c) both sets of instructions. Instructions had a weak facilitating effect in reducing fear. The absence of any instructions appeared to retard fear reduction. The efficacy of standardized, taped therapy is questioned. (28 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of problem definitions in understanding age and context effects on strategies for solving everyday problems.

The participants (107 preadolescents, 124 college students, 118 middle-aged adults, and 131 older adults) described 2 everyday problems (1 unconstrained, the other constrained to 1 of 6 domains) that they experienced and their goals and strategies. Problem definitions reflected interpersonal or competence components or both; strategies reflected altering cognitions, actions, or regulating and including others. Age differences in problem definitions were found. For unconstrained-domain problems, age and problem definition were related to strategies; for unconstrained-domain problems age differences in strategies were not found. For constrained-domain problems, strategies related to problem domain and problem definition, with problem definition the better predictor of strategies. The results illustrate the value of individuals' problem definitions for addressing age and context effects on strategies used. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the venous system in the abdominal flap of the rat

The abdominal flap of the rat has become a popular model with investigators. Recently, researchers have been reporting survival of skin flaps with varying blood supplies. We studied the viability of skin flaps on a consistent model with varied blood supply. An 8 x 9 cm flap was raised in 40 male Sprague-Dawley rats. The viability of the flaps could be studied in 25 rats. The survival of a pedicled flap based on the left inferior epigastric artery and vein was compared with that of a pedicled flap with enhanced venous drainage. The survival of a venous flap based on the paired inferior epigastric veins and the paired long thoracic veins was compared with that of an arterialized venous flap. A composite graft was used as a control for all groups. A qualitatively improved survival was found in the pedicled venous-enhanced group (66 percent) compared with the pedicled flaps (56 percent) (p > 0.05). An improved survival was found in the arterialized venous flap (57 percent) compared with the venous flap (40 percent) (p < 0.05). All flaps had improved survival compared with the composite graft (0.6 percent) (p < 0.05).     

Dissonance reduction in the context of group membership: The role of metaconsistency.

Recent work has established that groups can reduce dissonance by providing consonant cognitions, normative support, or an opportunity to diffuse responsibility for counterattitudinal behavior. Adopting a social identity framework, the current research comprised 2 studies examining metaconsistency, which was proposed to underlie these disparate explanations for the effect of social support. In Study 1 (N = 121), participants performed a counterattitudinal behavior with or without attitude and behavior support. As expected, congruence between the participants’ attitude–behavior consistency and another’s attitude–behavior consistency reduced attitude change. Study 2 (N = 69) replicated the results of Study 1; in addition, metaconsistency influenced participants’ perceptions of their own attitude–behavior consistency. The implications of metaconsistency for other contemporary perspectives of dissonance theory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of video feedback in the context of Milan Systemic therapy.

The authors compared the effectiveness of video feedback to verbal feedback within the context of Milan Systemic family therapy. Ten families were randomly assigned to either the video- or verbal-feedback condition, resulting in 16 participants in each condition. Families engaged in 5 wks of family therapy, which included either verbal or video feedback on a family interaction task. Changes from pretreatment to posttreatment were analyzed for several problem-related and family variables. Results indicated significant pretreatment posttreatment (controlling for family) interactions for responsibility for the problem and family adaptability. Support was found for the therapeutic effects of video feedback within Milan Systemic therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)