Electrolytic lesions of the medial prefrontal cortex do not interfere with long-term memory of extinction of conditioned fear

Lesion studies indicate that rats without the medial prefrontal cortex (mPFC) have difficulty recalling fear extinction acquired the previous day. Several electrophysiological studies have also supported this observation by demonstrating that extinction-related increases in neuronal activity in the mPFC participate in expression of fear extinction. However, a more recent study has shown that fear extinction can be recalled, in certain circumstances, without mPFC potentiation, suggesting contribution of other circuits. Here, we examined this possibility in rats that were subjected to auditory fear conditioning, extinction training, and extinction retention test 7 d later. Electrolytic lesions were made in the mPFC, the motor cortex (MO), the dorsal septum (SEP), or the mediodorsal thalamus (MD), because of their potential participation in conditioned fear inhibition; combined lesions including the mPFC with the MO, SEP, or MD were also made. The lesions were made either 1 wk before conditioning or 1 d after extinction training. All rats normally extinguished their conditioned freezing behavior during extinction training and did not display any return of this behavior during the retention test. These data reveal that the mPFC is not required for the acquisition, the expression, or the retrieval of extinction memories but do not exclude the possibility that the mPFC normally participates in these processes.     

The roles of semantic similarity and proactive interference in the word length effect

We examined the influence of semantic similarity and proactive interference (PI) on the word length effect (WLE) in immediate serial recall. Word length was manipulated by comparing memory for monosyllabic versus multisyllabic words. PI effects were evaluated by manipulating semantic similarity in the to-be-remembered lists and examining its impact on the WLE’s magnitude across eight-trial blocks. Words were sampled from a single semantic category across the entire block, from a single category within the list, or from different categories. Robust WLEs were observed in single-category blocks and when words were from different categories. However, when all the within-list words were from the same semantic category, the WLE was sharply attenuated. Except for the within-list semantic similarity condition, there was a buildup in PI levels in the form of protrusion errors across trials. However, the magnitude of the WLE did not increase with the PI buildup, suggesting that it was not affected by PI across trials.     

Religious identity among Christian Korean-American adolescents

This exploratory study examined religious identity among Christian Korean-American adolescents. Marcia's 1966 model of identity formation, which conceptualizes identity along dimensions of exploration and commitment, provided the framework for the current study. 49 participants, between the ages of 14 and 19 years, completed the Duke Religion Index, the religion items from the Extended Objective Measure of Ego Identity Status, the Pan-denominational Measure of Personal Devotion and Personal Conservatism, and six questions assessing perceived parental involvement. Analysis indicated that high scores on Organizational and Intrinsic Religiosity were positively correlated with the commitment statuses of Achievement and Foreclosure and negatively correlated with the noncommitment statuses of Moratorium and Diffusion. Also high scores on perceived parental involvement were positively correlated with the nonexploration status of Foreclosure and negatively correlated with the exploration status of Moratorium. Overall, the study provided a general portrait and initial examination of the formation of religious identity in a sample of Christian Korean-American adolescents.     

The future is now: prospective temporal self-appraisals among defensive pessimists and optimists

Three studies found that prospective temporal self-appraisals can be part of defensive pessimists' strategy; they felt closer to equally distant negative than positive futures. In Study 1, defensive pessimists felt closer to future failures and reported more negative affect than those considering success. In Study 2, when manipulated negative futures were close, defensive pessimists felt bad and performed well; results suggested that viewing negative futures as close may be part of their natural strategy. Study 3 found that prospective self-appraisals influenced performances through felt preparation. Optimists did not use prospective self-appraisals (Study 1) and their performances were unaffected by manipulated temporal distance (Studies 2 and 3). Discussion centers on prospective self-appraisals and multiple strategies of defensive pessimists.     

Establishing the feasibility of direct observation in the assessment of tics in children with chronic tic disorders

Behavior analysis has been at the forefront in establishing effective treatments for children and adults with chronic tic disorders. As is customary in behavior analysis, the efficacy of these treatments has been established using direct-observation assessment methods. Although behavior-analytic treatments have enjoyed acceptance and integration into mainstream health care practices for tic disorders (e.g., psychiatry and neurology), the use of direct observation as a primary assessment tool has been neglected in favor of less objective methods. Hesitation to use direct observation appears to stem largely from concerns about the generalizability of clinic observations to other settings (e.g., home) and a lack of consensus regarding the most appropriate and feasible techniques for conducting and scoring direct observation. The purpose of the current study was to evaluate and establish a reliable, valid, and feasible direct-observation protocol capable of being transported to research and clinical settings. A total of 43 children with tic disorders, collected from two outpatient specialty clinics, were assessed using direct (videotape samples) and indirect (Yale Global Tic Severity Scale; YGTSS) methods. Videotaped observation samples were collected across 3 consecutive weeks and two different settings (clinic and home), were scored using both exact frequency counts and partial-interval coding, and were compared to data from a common indirect measure of tic severity (the YGTSS). In addition, various lengths of videotaped segments were scored to determine the optimal observation length. Results show that (a) clinic-based observations correspond well to home-based observations, (b) brief direct-observation segments scored with time-sampling methods reliably quantified tics, and (c) indirect methods did not consistently correspond with the direct methods.     

Early changes in muscle activation patterns of toddlers during walking

Early locomotor behavior has been the focus of considerable attention by developmentalists over several decades. Few studies have addressed explicitly patterns of muscle activity that underlie this coordination pattern. Our purposes were to illustrate a method to determine objectively the onset and offset of muscle firings during early walking and to investigate the emergence of patterns of activation of the core locomotor muscles. We tested eight toddlers as they walked overground at walking onset (max. of 3-6 independent steps) and after three months of walking experience. Surface electrodes monitored activity of the gastrocnemius, tibialis anterior, quadriceps, and hamstrings. We reduced EMG signals to a frame-by-frame designation of "on-off," followed by muscle state and co-contraction analyses, and probability distributions for each muscle's activity across multiple cycles. Our results clearly show that at walking onset muscle activity was highly variable with few, if any, muscles showing recurring patterns of behavior, within or among toddlers. Variability and co-activation decreased with walking experience but remained inconsistent, in contrast to the significant increase in stability shown for joint coordination and endpoint (foot placement) parameters. We propose this trend emerges because of the high number of options (muscle combinations) available. Toddlers learn first to marshal sufficient force to balance and make forward progress but slowly discover how to optimize these resources.     

Category and feature identification

This paper considers a family of inductive problems where reasoners must identify familiar categories or features on the basis of limited information. Problems of this kind are encountered, for example, when word learners acquire novel labels for pre-existing concepts. We develop a probabilistic model of identification and evaluate it in three experiments. Our first two experiments explore problems where a single category or feature must be identified, and our third experiment explores cases where participants must combine several pieces of information in order to simultaneously identify a category and a feature. Humans readily solve all of these problems, and we show that our model accounts for human inferences better than several alternative approaches.     

Design-Based Guidelines for the Semantic Perception of Emergency Signs

The current study applies semantic differential to explore the semantic perception of emergency signs, in an attempt to analyze the meanings of emergency signs in regard to the psychological exigencies of the general public. The results indicate that problems concerning recognition accuracy have been observed, but also that the evaluation of the semantic meaning of the signs is positive. However, a number of emotional factors also emerge, indicating that if improvements should be made to the existing emergency signs, it would better facilitate evacuation in the event of an emergency. As for the design guidelines, the emergency signs should be readily recognizable and have a single meaning. Multiple symbolic meanings should be eliminated. Concrete design guidelines include: (a) safety movement, (b) clarity, and (c) safety. To avoid confusion in sign recognition, in addition to the improvements made based on the abovementioned guidelines, educational promotional activities carried out by the government would also prove very beneficial.     

Effect of applied stress on precipitation of Guinier–Preston zones in a Cu–0.9 wt.% Be single crystal

A stress-oriented formation of plate-shaped Guinier–Preston (GP) zones in single crystals of a Cu–0.9?wt.%?Be alloy aged at 200°C has been found. A compressive stress applied in the [001] direction assists the formation of the GP zones perpendicular to the [001] axis, while a tensile stress results in the preferential formation of the GP zones parallel to the stress axis. The applied stress strongly affects the nucleation of the GP zones. Free ageing at 275°C after compressive-stress ageing at 200°C produces plate-shaped γ′′ precipitates perpendicular to the stress axis, indicating a continuous change in the structure of the GP zones into that of the γ′′ phase. From length-change measurements during ageing, the misfit strains of the GP zone or γ′′ precipitate in directions parallel and perpendicular to the plate plane are estimated, respectively, as ?0.01 and ?0.10 for the GP zone and ?0.01 and ?0.11 for the γ′′ precipitate.