Correlation between Changes in Stress-Induced Corticosterone Secretion and GR mRNA Levels

The current study was conducted to determine the potential relationship between stress-induced corticosterone secretion and corticosteroid receptor mRNA levels after 5 days of intermittent stress. In particular, we were interested in the rate at which animals terminate a stress response, and how this termination may be altered by repeated stress. Adult male Sprague-Dawley rats were subjected to either 5 days of restraint stress or 5 days of an unpredictable stress paradigm. Restraint-stress induced corticosterone secretion was measured on Days 1 and 5 in both groups, and animals were killed on Day 6. Glucocorticoid receptor (GR), and mineralocorticoid (MR) mRNA levels were determined using in-situ hybridization techniques. Five days of restraint stress caused an habituation of the plasma corticosterone response to stress measured 60 and 90 min post-stress initiation; this pattern of corticosterone secretion was not observed in the animals subjected to unpredictable stress. Five days of either stress paradigm did not alter MR mRNA levels measured within the hippocampus or GR mRNA levels within the hippocampus or the medial parvocellular division of the paraventricular nucleus of the hypothalamus (mpPVN). However, an individual's GR mRNA levels measured within the CA1/2 region of the hippocampus and the mpPVN were significantly correlated with the degree of habituation of the corticosterone response to stress measured on Day 5. This suggests that an increase in the rate of termination of the stress response and levels of GR within the hippocampus and mpPVN may be functionally related.     

Effects of physical exercise on peripheral vision and learning in children with spina bifida manifesta

The purpose of this research was to investigate the effects of active exercise of the arms on various physiological, perceptual, and cognitive parameters of children with spina bifida manifesta who were aged 9 to 12 yr. Following a 5-min. rest interval, subjects were either not exercised (control days) for a 6-min. period or were exercised (experimental days) for a 6-min. period. Cardiac measures, respiratory function, peripheral vision, and figural learning trials were recorded after exercise. Wilcoxon matched-pairs signed rank tests were computed on the means of the exercise and no-exercise conditions for each measure. Six minutes of active exercise resulted in significant increases in peripheral vision, respiratory and cardiac measures and significant decreases in figural learning trials for these children. A floor effect was noted for the figural learning test. It was concluded that exercise increased blood flow through the lungs allowing for greater oxygen diffusion in the brain and other facilitatory effects resulting in more effective cerebral activity. Curriculum revisions for such children seem to indicate the importance of activity in facilitating subsequent learning.     

Instant of chair-rise lift-off can be predicted by foot-floor reaction forces

OBJECTIVE: To develop a predictive model of the lift-off event during chair rise in healthy subjects, using foot-floor reaction forces. BACKGROUND: An important event during chair rise is lift-off from the seat: the transition from the inherently stable three-point contact to the unstable two-point contact. There is no consistent or generally agreed upon method for estimating the time of lift-off when an instrumented seat is unavailable. METHODS: Twenty healthy volunteers were divided into a testing set and training set. Each subject performed repeated chair rise trials at different speeds. Seat-floor and foot-floor forces, recorded with two force platforms, were used to develop a model of the lift-off event. RESULTS: The magnitude of the vertical foot-floor reaction at lift-off (F0VF) was linearly related (R2 = 0.71, P < 0.001) to the peak vertical foot-floor reaction force (FMVF). A linear model was developed for the training group, which enabled prediction of lift-off time for the testing group with an absolute average error of 6 ms (about 1 data frame at 150 Hz). The linear model derived for the entire sample was: F0VF = 28.14 + FMVF * (0.6434). CONCLUSIONS: The lift-off event for healthy subjects performing chair rise can be accurately predicted from foot-floor reaction forces, without requiring an instrumented seat.     

Validation of the German version of Cloninger's TPQ: Replication and correlations with stress coping, mood measures and drug use

The tridimensional personality questionnaire (TPQ) was developed by Cloninger (1986, 1987a) to measure the independent personality dimensions Novelty Seeking (NS), Harm Avoidance (HA) and Reward Dependence (RD). After having investigated the basic psychometric properties of a German version of the TPQ in a first study (Weyers et al., 1995), a new sample of 200 subjects was collected to investigate the reliability of the results of this first study and to add further validity data by including measures of stress coping, mood and drug use. In general, the results of the first study were replicated. The internal consistencies of the superscales NS, HA and RD were high, and a factor analysis of the TPQ subscales yielded some support for Cloninger's personality theory. Because of its strong correlations with Psychoticism, Extraversion, Impulsiveness and Sensation Seeking NS seems to tap an impulsivity factor while HA correlates with Neuroticism and Introversion and appears to measure a behavioral inhibition factor, the latter interpretation being supported by correlations between HA and some mood measures like anxiety and self-confidence. In addition, HA showed substantial positive correlations with coping strategies like Rumination, Resignation and Self-pity and substantial negative correlations with strategies like Self-aggrandizement by Comparison with Others and Positive Self-instructions, while the other two TPQ superscales hardly correlate with any of the coping strategies measured. With respect to drug use, only NS showed small but substantial bivariate correlations with the use of nicotine and psychodysleptics for the last 12 weeks and last 2 years. However, a configurational analysis of the TPQ superscales demonstrated that the type II alcoholism pattern proposed by Cloninger (high NS, low HA and low RD) was associated with a strong alcohol consumption.     

Reward prospect rapidly speeds up response inhibition via reactive control

Response inhibition is an important cognitive-control function that allows for already-initiated or habitual behavioral responses to be promptly withheld when needed. A typical paradigm to study this function is the stop-signal task. From this task, the stop-signal response time (SSRT) can be derived, which indexes how rapidly an already-initiated response can be canceled. Typically, SSRTs range around 200 ms, identifying response inhibition as a particularly rapid cognitive-control process. Even so, it has recently been shown that SSRTs can be further accelerated if successful response inhibition is rewarded. Since this earlier study effectively ruled out differential preparatory (proactive) control adjustments, the reward benefits likely relied on boosted reactive control. Yet, given how rapidly such control processes would need to be enhanced, alternative explanations circumventing reactive control are important to consider. We addressed this question with an fMRI study by gauging the overlap of the brain networks associated with reward-related and response-inhibition-related processes in a reward-modulated stop-signal task. In line with the view that reactive control can indeed be boosted swiftly by reward availability, we found that the activity in key brain areas related to response inhibition was enhanced for reward-related stop trials. Furthermore, we observed that this beneficial reward effect was triggered by enhanced connectivity between task-unspecific (reward-related) and task-specific (inhibition-related) areas in the medial prefrontal cortex (mPFC). The present data hence suggest that reward information can be translated very rapidly into behavioral benefits (here, within ~200 ms) through enhanced reactive control, underscoring the immediate responsiveness of such control processes to reward availability in general.     

Utilization of reward-prospect enhances preparatory attention and reduces stimulus conflict

The prospect of gaining money is an incentive widely at play in the real world. Such monetary motivation might have particularly strong influence when the cognitive system is challenged, such as when needing to process conflicting stimulus inputs. Here, we employed manipulations of reward-prospect and attentional-preparation levels in a cued-Stroop stimulus conflict task, along with the high temporal resolution of electrical brain recordings, to provide insight into the mechanisms by which reward-prospect and attention interact and modulate cognitive task performance. In this task, the cue indicated whether or not the participant needed to prepare for an upcoming Stroop stimulus and, if so, whether there was the potential for monetary reward (dependent on performance on that trial). Both cued attention and cued reward-prospect enhanced preparatory neural activity, as reflected by increases in the hallmark attention-related negative-polarity ERP slow wave (contingent negative variation [CNV]) and reductions in oscillatory Alpha activity, which was followed by enhanced processing of the subsequent Stroop stimulus. In addition, similar modulations of preparatory neural activity (larger CNVs and reduced Alpha) predicted shorter versus longer response times (RTs) to the subsequent target stimulus, consistent with such modulations reflecting trial-to-trial variations in attention. Particularly striking were the individual differences in the utilization of reward-prospect information. In particular, the size of the reward effects on the preparatory neural activity correlated across participants with the degree to which reward-prospect both facilitated overall task performance (shorter RTs) and reduced conflict-related behavioral interference. Thus, the prospect of reward appears to recruit attentional preparation circuits to enhance processing of task-relevant target information.     

Sources of variation in moral judgment: Toward a model of real-life morality

To evaluate the extent to which the models of moral judgment advanced by Kohlberg (1984) and by Gilligan (1982, 1988) are able to account for real-life moral judgment, we investigated the relation of sex and type of moral dilemma to moral stage and moral orientation. Eighty young adult men and women made moral judgments about two hypothetical Kohlberg dilemmas, two real-life antisocial dilemmas, and two real-life prosocial dilemmas. We failed to find any sex differences in moral judgment. Moral stage and moral orientation varied across the three types of dilemma. Kohlberg's dilemmas pulled for justice-oriented Stage 4 moral judgments, real-life prosocial dilemmas pulled for care-oriented Stage 3 moral judgments, and real-life antisocial dilemmas pulled for justice-oriented Stage 2 moral judgments. The content of moral judgments was related to their structure. There was a positive relation between stage of moral judgment on Kohlberg dilemmas and on real-life dilemmas. The implications of these findings for a new, more interactional, model of real-life moral judgment are discussed.