Hippocampal train stimulation modulates recall of fear extinction independently of prefrontal cortex synaptic plasticity and lesions

It has been shown that long-term potentiation (LTP) develops in the connection between the mediodorsal thalamus (MD) and the medial prefrontal cortex (mPFC) and between the hippocampus (HPC) and the mPFC following fear extinction, and correlates with extinction retention. However, recent lesion studies have shown that combined lesions of the MD and mPFC do not interfere with extinction learning and retention, while inactivation of the dorsal HPC disrupts fear extinction memory. Here we found in rats that immediate post-training HPC low-frequency stimulation (LFS) suppressed extinction-related LTP in the HPC-mPFC pathway and induced difficulties in extinction recall. HPC tetanus, applied several hours later, failed to re-establish mPFC LTP but facilitated recall of extinction. Delayed post-training HPC LFS also provoked mPFC depotentiation and difficulties with extinction recall. HPC tetanus abolished these two effects. We also found that damage to the mPFC induced fear return only in rats that received HPC LFS following extinction training. HPC tetanus also reversed this behavioral effect of HPC LFS in lesioned rats. These data suggest that the HPC interacts with the mPFC during fear extinction, but can modulate fear extinction independently of this interaction.     

Dual route for subtask order control: Evidence from the psychological refractory paradigm

A change in subtask order in the psychological refractory period (PRP) paradigm increases the effect of stimulus onset asynchrony (SOA) on the second response. We used a paradigm with cued, randomly determined subtask order to test the hypothesis that this SOA by order switch overadditivity reflects order control, via “copying” stimulus order. In Experiments 1a and 1b, overadditivity was evident only with insufficient opportunity for cue-based order control. In Experiment 2, overadditivity was decreased by using the same set of stimuli in the two subtasks, presumably by removing the opportunity to rely on stimulus order. In Experiment 3, removing the order cue increased the overadditivity, presumably because control was based solely upon copying stimulus order. The results indicate interactive top-down and bottom-up order control. Implications to theories of the PRP paradigm are discussed.     

Native Thai Speakers’ Acquisition of English Word Stress Patterns

The influence of syllabic structure, lexical class and stress patterns of known words on the acquisition of the English stress system was investigated in ten native Thai speakers. All participants were adult learners of English with an average length of residence in the US of 1.4 years. They were asked to produce and give perceptual judgments on 40 English non-words of varying syllabic structures in noun and verb sentence frames. Results of the production data suggested that syllables with a long vowel attracted stress more often than syllables containing a short vowel and nouns received initial stress more often than verbs. Additionally, regression analyses with the three factors as predictors suggested that Thai participants’ pattern of stress assignment on non-words was significantly influenced by the stress patterns of phonologically similar real words. These results were compared and contrasted to those found in previous work with Spanish–English and Korean–English bilinguals.     

Sex-role-related differences in self-concept and mental health

Examined the differences in serf-concept and psychological health between androgynous, sex-typed, cross-sex-typed, and undifferentiated males and females. Two hundred forty-nine students who were enrolled in introductory psychology classes were classified according to sex type on the basis of their scores on the Bem Sex-Role Inventory. Nine aspects of self-concept and five aspects of psychological health, obtained, from the Tennessee Self-Concept Scale, were analyzed as a function of Sex and Sex Type. A series of analyses of variance and subsequent individual comparisons across groups revealed a clear pattern wherein androgynous subjects manifested more positive self-concepts and more positive psychological health than sex-typed subjects. Undifferentiated subjects manifested the poorest self-concepts, while results for sex-typed and cross-sex-typed subjects varied more as a function of the sex of the subject. The data are discussed as appearing to be consistent with Bem's hypothesis that androgynous people may represent a more appropriate societal definition of mental health than strongly sex-typed people. Qualifications of this support are also discussed.     

False memories and lexical decision: even twelve primes do not cause long-term semantic priming

Semantic priming effects are usually obtained only if the prime is presented shortly before the target stimulus. Recent evidence obtained with the so-called false memory paradigm suggests, however, that in both explicit and implicit memory tasks semantic relations between words can result in long-lasting effects when multiple 'primes' are presented. The aim of the present study was to investigate whether these effects would generalize to lexical decision. In four experiments we showed that even as many as 12 primes do not cause long-term semantic priming. In all experiments, however, a repetition priming effect was obtained. The present results are consistent with a number of other results showing that semantic information plays a minimal role in long-term priming in visual word recognition.     

Epistemological beliefs and thinking about everyday controversial issues

The authors investigated the relationship between individuals' beliefs about the nature of knowledge and the nature of learning (epistemological beliefs) and their thinking about everyday controversial issues. Adults (N = 174) ranging in age from 17 to 71 years old with a mean age of 38 completed the Schommer Epistemological Questionnaire (M. Schommer, 1990), which assessed their beliefs in the certainty and organization of knowledge and the speed and control of learning. After they had completed the questionnaire, they responded to a series of questions about two controversial issues that had been discussed in the local newspaper. Regression analyses indicated that the more the participants believed in complex and tentative knowledge, the more likely they were to take on multiple perspectives, be willing to modify their thinking, withhold ultimate decisions until all information was available, and acknowledge the complex, tentative nature of everyday issues. Epistemological beliefs that are heavily influenced by a higher level of education appear to relate to thinking beyond the classroom, and introducing controversial issues into the curriculum may reciprocally foster the development of epistemological beliefs.     

Anxiety-related bias in the classification of emotionally ambiguous facial expressions

High- and low-trait socially anxious individuals classified the emotional expressions of photographic quality continua of interpolated ("morphed") facial images that were derived from combining 6 basic prototype emotional expressions to various degrees, with the 2 adjacent emotions arranged in an emotion hexagon. When fear was 1 of the 2 component emotions, the high-trait group displayed enhanced sensitivity for fear. In a 2nd experiment where a mood manipulation was incorporated, again, the high-trait group exhibited enhanced sensitivity for fear. The low-trait group was sensitive for happiness in the control condition. The mood-manipulated group had increased sensitivity for anger expressions, and trait anxiety did not moderate these effects. Interpretations of the results related to the classification of fearful expressions are discussed.