Stressful life events, bipolar disorder, and the "kindling model"

A common misconception is that bipolar disorder is an endogenous process. However, previous research suggests a role for life events in the onset of and recovery from bipolar episodes. Yet, there remains some question as to whether the relationship between life events and onset changes over the course of the disorder as a result of the number of episodes an individual has experienced. Using a rigorous interview measure of stressful life events, the current study tested the kindling model (R. M. Post, 1992), which theorizes that major life events play a diminishing role over the course of illness in bipolar patients. Analyses revealed that the number of episodes experienced does not appear to have a significant effect on bipolar 1 patients' reactivity to external stressors. In addition, the results suggest that a more complex relationship exists among age, stress, and onset of new episodes than can be adequately explained by the kindling model.     

Stress and immune system function in a newspaper's newsroom

Data were collected on 10 newswriters in a newspaper's newsroom. These included self-reported stress ratings and saliva samples for secretary immunoglobulin A (IgA) analysis. The stress ratings and saliva samples were taken initially and after three 30-min. periods. The first time period was a baseline measure and involved the workers engaging in their usual tasks. At Time 2 music was presented for 30 min. while workers engaged in their normal activities. At Time 3 workers resumed their normal duties. Findings showed an increase in IgA that was not statistically significant, a reduction in stress during the music period that was statistically significant, and a statistically significant negative correlation between stress and IgA.     

Persistent neuroendocrine changes in multiple hormonal axes after a single or repeated stressor exposures

Many researchers have studied acute responses to stress in animals and how they are modified by prior stressor exposure, but relatively few have examined whether responses to stressors might last for prolonged periods of time. We have previously demonstrated that trough plasma corticosterone levels in rats are elevated for three to five days after single or repeated exposures to mild restraint and inescapable tailshock. The current study measured other aspects of the adrenal axis, and activity in other neuroendocrine systems, 24 hours after one or three consecutive exposures to the same stress paradigm. The data indicated persistent activation of the adrenal axis and prolactin levels, whereas the thyroid and reproductive hormone axes were inhibited after either one or three stress sessions. These changes are remarkable in that one would have expected acute responses to even intense stressors to have ended within hours after the end of the stressor. It will be important to understand the interactions among these responding neuroendocrine systems and to know how long such persistent changes last. Finally, it will be critical to understand the relative contributions of neuroendocrine and psychological factors in maintaining these persistent neuroendocrine changes after exposure to intense stressors.     

A cGMP-dependent protein kinase gene, foraging, modifies habituation-like response decrement of the giant fiber escape circuit in Drosophila

The Drosophila giant fiber jump-and-flight escape response is a model for genetic analysis of both the physiology and the plasticity of a sensorimotor behavioral pathway. We previously established the electrically induced giant fiber response in intact tethered flies as a model for habituation, a form of nonassociative learning. Here, we show that the rate of stimulus-dependent response decrement of this neural pathway in a habituation protocol is correlated with PKG (cGMP-Dependent Protein Kinase) activity and foraging behavior. We assayed response decrement for natural and mutant rover and sitter alleles of the foraging (for) gene that encodes a Drosophila PKG. Rover larvae and adults, which have higher PKG activities, travel significantly farther while foraging than sitters with lower PKG activities. Response decrement was most rapid in genotypes previously shown to have low PKG activities and sitter-like foraging behavior. We also found differences in spontaneous recovery (the reversal of response decrement during a rest from stimulation) and a dishabituation-like phenomenon (the reversal of response decrement evoked by a novel stimulus). This electrophysiological study in an intact animal preparation provides one of the first direct demonstrations that PKG can affect plasticity in a simple learning paradigm. It increases our understanding of the complex interplay of factors that can modulate the sensitivity of the giant fiber escape response, and it defines a new adult-stage phenotype of the foraging locus. Finally, these results show that behaviorally relevant neural plasticity in an identified circuit can be influenced by a single-locus genetic polymorphism existing in a natural population of Drosophila.     

Perceived discrimination and substance use in African American parents and their children: a panel study

The relation between perceived racial discrimination and substance use was examined in a panel of 684 African American families, using the prototype-willingness model of adolescent health risk (F. X. Gibbons, M. Gerrard, & D. Lane, 2003). Discrimination was concurrently and prospectively related to use in the parents and the children (mean age=10.5 years at Wave 1). The discrimination-->use relation in the parents was mediated by distress (anxiety and depression). Among the children, the relation was mediated by distress as well as their risk cognitions (favorability of their risk images and their willingness to use) and the extent to which they reported affiliating with friends who were using substances. Each of these relations with discrimination was positive. In contrast, effective parenting was associated with less willingness and intention to use. Theoretical and applied implications of the results are discussed.     

Spontaneous humor among right hemisphere stroke survivors

We analyzed spontaneous conversational humor production and response among 11 right hemisphere-damaged (RHD) patients, 10 left hemisphere-damaged (LHD) patients, 7 normal controls (NC), and their spouses. RHD patients and their spouses reported a statistically significant decline in the patients' orientation to humor post-stroke. Also, we found a significant positive association between a RHD patient's ability to decode prosody and their self-reported orientation to humor post-stroke.     

Preserved spatial memory over brief intervals in older adults

Two studies compared young and older adults' memory for location information after brief intervals. Experiment 1 found that accuracy of intentional spatial memory for individual locations was similar in young and older participants for set sizes of 3 and 6. Both groups also encoded individual locations in relation to the larger configuration of locations. Experiment 2 showed that like young adults, older adults' latency to respond to a test probe in a letter working memory task was negatively influenced by spatial information that was irrelevant to the task. This interference effect indicated preserved incidental memory for spatial information in older adults. Together, these data suggest that initial encoding of spatial information for relatively small numbers of items is largely preserved in healthy older adults and that representations of spatial information persist over short intervals.     

Relative area and relative luminance combine to anchor surface lightness values.

The anchoring of lightness perception was tested in simple visual fields composed of only two regions by placing observes inside opaque acrylic hemispheres. Both side-by-side and center/surround configurations were tested. The results, which undermine Gilchrist and Bonato's (1995) recent claim that surrounds tend to appear white, indicate that anchoring involves both relative luminance and relative area. As long as the area of the darker region is equal to or smaller than the area of the lighter region, relative area plays no role in anchoring. Only relative luminance controls anchoring: The lighter region appears white, and the darker region is perceived relative to that value. When the area of the darker region becomes greater than that of the lighter region, relative area begins to play a role. As the darker region becomes larger and relative area shifts from the lighter region to the darker region, the appearance of the darker region moves toward white and the appearance of lighter region moves toward luminosity. This hitherto unrecognized rule is consistent with almost all of the many previous reports of area effects in lightness and brightness. This in turn suggests that a wide range of earlier work on area effects in brightness induction, lightness contrast, lightness assimilation, and luminosity perception can be understood in terms of a few simple rules of anchoring.     

生物反馈放松训练和表象训练在飞行训练中的应用研究

本研究试用生物反馈放松训练和表象训练相结合方法,减轻飞行学员的精神紧张及有关的生理反应、２６名２０—２２岁的男性飞行学员,实验、对照组各１３名、实验组学员每次飞行后进行一次肌电生物反馈放松训练和起落航线表象训练,共１６次;对照组学员参加日常飞行训练不加任何干预。实验前后实验组及对照组学员进行黑红数字测试,记录其测试前后的血压、心率;第一次升空及单飞考核飞行后也记录他们的血压和心率。结果表明,实验组学员的单飞考核成绩优于对照组;实验织学员单飞考核后的收缩压及第二次黑红数字测试后的收缩压比实验前显著降低;而对照组的前述生理指标无变化。生物反馈放松训练和表象训练能有效地减轻飞行中的紧张情绪及其生理反应,适于在飞行部队应用。