A link between stress and depression: shifts in the balance between the kynurenine and serotonin pathways of tryptophan metabolism and the etiology and pathophysiology of depression

Alteration of tryptophan (TRP) metabolism elicited by proinflammatory cytokines has gained attention as a new concept to explain the etiological and pathophysiological mechanisms of major depression. The kynurenine (KYN) pathway, which is initiated by indoleamine 2,3-dioxygenase (IDO), is the main TRP metabolic pathway. It shares TRP with the serotonin (5-HT) pathway. Proinflammatory cytokines induce IDO under stress, promote the KYN pathway, deprive the 5-HT pathway of TRP, and reduce 5-HT synthesis. The resultant decrease in 5-HT production may relate to the monoamine hypothesis of major depression. Furthermore, metabolites of the KYN pathway have neurotoxic/neuroprotective activities; 3-hydroxykynurenine and quinolinic acid are neurotoxic, whereas kynurenic acid is neuroprotective. The hippocampal atrophy that appears in chronic depression may be associated with imbalances in neurotoxic/neuroprotective activities. Because proinflammatory cytokines also activate the hypothalamo-pituitary-adrenal (HPA) axis, these imbalances may inhibit the hippocampal negative feedback system. Thus, changes in the TRP metabolism may also relate to the HPA axis-hyperactivity hypothesis of major depression. In this article, we review the changes in TRP metabolism by proinflammatory cytokines under stress, which is assumed to be a risk factor for major depression, and the relationship between physiological risk factors for major depression and proinflammatory cytokines.     

Working memory, attention control, and the N-back task: a question of construct validity

The N-back task requires participants to decide whether each stimulus in a sequence matches the one that appeared n items ago. Although N-back has become a standard "executive" working memory (WM) measure in cognitive neuroscience, it has been subjected to few behavioral tests of construct validity. A combined experimental- correlational study tested the attention-control demands of verbal 2- and 3-back tasks by presenting n = 1 "lure" foils. Lures elicited more false alarms than control foils in both 2- and 3-back tasks, and lures caused more misses to targets that immediately followed them compared with control targets, but only in 3-back tasks. N-back thus challenges control over familiarity-based responding. Participants also completed a verbal WM span task (operation span task) and a marker test of general fluid intelligence (Gf; Ravens Advanced Progressive Matrices Test; J. C. Raven, J. E. Raven, & J. H. Court, 1998). N-back and WM span correlated weakly, suggesting they do not reflect primarily a single construct; moreover, both accounted for independent variance in Gf. N-back has face validity as a WM task, but it does not demonstrate convergent validity with at least 1 established WM measure.     

Combined predisposed preferences for colour and biological motion make robust development of social attachment through imprinting

Animal Cognition - To study how predisposed preferences shape the formation of social attachment through imprinting, newly hatched domestic chicks (Gallus gallus domesticus) were simultaneously...     

Production of recrystallized nano-grains in a fine-grained Cu–Zn alloy

A fine-grained Cu–30%Zn alloy sheet was rolled at 77 K to induce ultrafine mechanical twins. Subsequent annealing of the rolled alloy at temperatures up to 543 K led to the uniform appearance of recrystallized ultrafine grains (UFGs), which contained numerous annealing twins. Average grain sizes of 150 ～ 300 nm were produced in this way. The formation of such UFGs during annealing is attributed to the high nucleus density associated with the fine initial grain size as well as to the high densities of mechanical twins and dislocations produced by cryorolling. The high driving force for recrystallization enabled the use of relatively low annealing temperatures, which limited the subsequent grain growth.     

Coordination modes in sensorimotor synchronization of whole-body movement: a study of street dancers and non-dancers

This study investigated whole-body sensorimotor synchronization (SMS) in street dancers and non-dancers. Two kinds of knee bending movement in a standing position to a metronome beat were explored in terms of stability under different movement frequencies: down-movement condition (knee flexion on the beat) and up-movement condition (knee extension on the beat). Analyses of phase relation between movement and beat revealed several distinct differences between the down- and up-movement conditions, and between dancers and non-dancers. In both groups under the up-movement condition, deviation from intended phase relation at higher beat rates, and enhanced fluctuations were observed. The deviation from intended phase relation under up-movement condition, and movement fluctuations were greater in non-dancers than in dancers. Moreover, subjective difficulty rating revealed that both groups felt that the up-movement condition was more difficult at higher beat rates. These findings suggest that down and up movements are two distinguishable coordination modes in whole-body coordination, and that street dancers have superior whole-body SMS ability.     

Assessing the reliability of Curriculum-Based Measurement: an application of Latent Growth Modeling

The purpose of this study was to demonstrate the use of Latent Growth Modeling (LGM) as a method for estimating reliability of Curriculum-Based Measurement (CBM) progress-monitoring data. The LGM approach permits the error associated with each measure to differ at each time point, thus providing an alternative method for examining of the reliability of CBM reading aloud data over repeated measurements. The analysis revealed that the reliability of CBM data was not a fixed property of the measure, but it changed with time. The study demonstrates the need to consider reliability in new ways with respect to the use of CBM data as repeated measures.     

Gender differences in enrollment in computer camps and classes

Informal reports suggest that computer literacy (computer awareness and programming skills) is sought more often by boys than girls. In order to gather more systematic data on this possibility, questionnaires were sent in the summer of 1982 to directors of summer camps and classes that offered training in programming for microcomputers. Twenty-three directors of summer programs, serving a total of 5,533 students, provided data on enrollment, type of sponsorship of programs (private, public schools, universities), level of difficulty of programming classes, cost, and residential versus day use. Three times as many boys as girls were enrolled in the total sample. The ratio of males to females increased with grade, cost of program, and level of difficulty of course offerings. Possible explanations for differences in enrollment are discussed.     

Credit and blame among American and Japanese children: normative, cultural, and individual differences

Japanese and American 5th graders (N = 593 children, 198 American and 395 Japanese) assigned credit and blame to good and bad classroom deeds and performances. Theoretically, a morality of aspiration involves assigning more credit for a good deed than blame for a corresponding bad deed; a morality of duty involves assigning more blame than credit. In both countries academic achievement norms were most consistent with aspiration, moral norms were judged as duties, and procedural norms were intermediate. Japanese children's responses were more consistent with aspiration than those of Americans. Analyses also explored cultural versus individual differences in sanctioning. The conclusion addresses the relevance of the concept of aspiration to the study of achievement and other norms.     

The relationship of computer self-efficacy expectations to computer interest and course enrollment in college

Gender differences in perceived self-efficacy for computer use may help account for differential computer interest and course enrollment at the college level. Three hundred sixty-eight students completed a two-page questionnaire assessing perceived computer self-efficacy, plans to take a computer science course, perceived importance of computing skills, and interest in learning about computers. Men rated themselves higher than did women for perceived self-efficacy. They were also more positive on the cognitive outcome measures, but with computer self-efficacy held constant, the magnitude of these differences was decreased, suggesting that perceived self-efficacy may be an important consideration when examining gender differences in computer interest and use.The author wishes to thank Dr. Martin Ford and Dr. Albert Bandura for their helpful comments on an earlier version of this article. This research was supported by a grant from the San Jose State University Foundation. Portions of this research were reported at the annual meetings of the American Educational Research Association in San Francisco, April 1986.