Chronic stress and sex differences on the recall of fear conditioning and extinction

Chronic stress effects and sex differences were examined on conditioned fear extinction. Male and female Sprague–Dawley rats were chronically stressed by restraint (6 h/d/21 d), conditioned to tone and footshock, followed by extinction after 1 h and 24 h delays. Chronic stress impaired the recall of fear extinction in males, as evidenced by high freezing to tone after the 24 h delay despite exposure to the previous 1 h delay extinction trials, and this effect was not due to ceiling effects from overtraining during conditioning. In contrast, chronic stress attenuated the recall of fear conditioning acquisition in females, regardless of exposure to the 1 h extinction exposure. Since freezing to tone was reinstated following unsignalled footshocks, the deficit in the stressed rats reflected impaired recall rather than impaired consolidation. Sex differences in fear conditioning and extinction were observed in nonstressed controls as well, with control females resisting extinction to tone. Analysis of contextual freezing showed that all groups (control, stress, male, female) increased freezing immediately after the first tone extinction trial, demonstrating contextual discrimination. These findings show that chronic stress and sex interact to influence fear conditioning, with chronic stress impairing the recall of delayed fear extinction in males to implicate the medial prefrontal cortex, disrupting the recall of the fear conditioning acquisition in females to implicate the amygdala, and nonstressed controls exhibiting sex differences in fear conditioning and extinction, which may involve the amygdala and/or corticosterone levels.     

Attentional bias toward threat in contamination fear: overt components and behavioral correlates

Recent research suggests that an attentional bias toward threat may play a causal role in obsessive-compulsive disorder (OCD) with contamination concerns. However, the attentional components involved in this bias, as well as its behavioral correlates, remain unclear. In the present study, eye movements were recorded in individuals high and low in contamination fear (HCF, LCF, respectively) during 30-s exposures to stimulus arrays containing contamination threat, general threat, pleasant, and neutral images. HCF individuals oriented gaze toward contamination threat more often than LCF individuals in initial fixations, and this bias mediated group differences in responding to a behavioral challenge in a public restroom. No group differences were found in the maintenance of gaze on contamination threat, both in terms of initial gaze encounters, as well as gaze duration over time. However, the HCF group made shorter fixations on contamination threat relative to other image types. The implications of these findings for further delineating the nature and function of attentional biases in contamination-based OCD are discussed.     

Consolidation and translation regulation

mRNA translation, or protein synthesis, is a major component of the transformation of the genetic code into any cellular activity. This complicated, multistep process is divided into three phases: initiation, elongation, and termination. Initiation is the step at which the ribosome is recruited to the mRNA, and is regarded as the major rate-limiting step in translation, while elongation consists of the elongation of the polypeptide chain; both steps are frequent targets for regulation, which is defined as a change in the rate of translation of an mRNA per unit time. In the normal brain, control of translation is a key mechanism for regulation of memory and synaptic plasticity consolidation, i.e., the off-line processing of acquired information. These regulation processes may differ between different brain structures or neuronal populations. Moreover, dysregulation of translation leads to pathological brain function such as memory impairment. Both normal and abnormal function of the translation machinery is believed to lead to translational up-regulation or down-regulation of a subset of mRNAs. However, the identification of these newly synthesized proteins and determination of the rates of protein synthesis or degradation taking place in different neuronal types and compartments at different time points in the brain demand new proteomic methods and system biology approaches. Here, we discuss in detail the relationship between translation regulation and memory or synaptic plasticity consolidation while focusing on a model of cortical-dependent taste learning task and hippocampal-dependent plasticity. In addition, we describe a novel systems biology perspective to better describe consolidation.     

Subliminal understanding of negation: Unconscious control by subliminal processing of word pairs

A series of five experiments investigated the extent of subliminal processing of negation. Participants were presented with a subliminal instruction to either pick or not pick an accompanying noun, followed by a choice of two nouns. By employing subjective measures to determine individual thresholds of subliminal priming, the results of these studies indicated that participants were able to identify the correct noun of the pair – even when the correct noun was specified by negation. Furthermore, using a grey-scale contrast method of masking, Experiment 5 confirmed that these priming effects were evidenced in the absence of partial awareness, and without the effect being attributed to the retrieval of stimulus–response links established during conscious rehearsal.     

The Draw-A-Person Test and Process-Reactive Schizophrenia

The Draw-A-Pcrson test was administered to three matched groups of 32 male Ss each: reactive schizophrenics, process schizophrenics, and normal control subjects. Patients were rated for prognosis using the Premorbid Subscale of the Phillips Scale. Drawings were rated by two judges on 80 diagnostic signs culled from the literature. No signs were found to significantly differentiate reactive and process schizophrenics, and only three signs significantly differentiated normals from schizophrenics. It was concluded that a sign approach to the DAP is insensitive to the reaction-process dimension of schizophrenia, and of only limited value in differentiating between normals and schizophrenics in general.     

The black community's reactions to the 1992 los angeles riot

This article is based on field (street) interviews with a sample of 227 black community members living and/or working in South Central Los Angeles at the time of the 1992 riot. The interview instrument comprises 20 questions designed to (1) ascertain the reactions and feelings of black community members to the riot; and (2) compare a sample of black participants in the riot with nonparticipants. The participant group was found to be more frequently younger males with less education and lower income, and they were more likely to have arrest records prior to the riot than nonparticipants. Though reactions and feelings were mixed and contradictory, both groups reported an overall acceptance of the disorders. Differentials in reactions were in degree rather than in kind. Most objected to the riot in principle but concluded that collective violence “pays off.” The preriot structural facilitators (poverty, relative deprivation, unemployment, police brutality, racial discrimination, and negative police‐community relations) were similar to those found in the riot literature. Whatever the participants’ reasons and justifications for rioting might be, they present themselves as worthy protesters and freedom fighters. Unless their message is heeded and acted upon by ameliorating their adverse social, economic, and political conditions, similar riots are likely to occur.