Temporal Coding in Pavlovian Conditioning: Hall-Pearce Negative Transfer

The Hall-Pearce (1979) negative transfer effect in rats was used to examine whether temporal relationships are coded as part of the informational content of associations that result from CS-US pairings. The transfer effect consists of adeficit in conditioned responding following CS-US pairings in Phase 2 that results from prior CS-US pairings in Phase 1. strong weak Using conditioned bar-press suppression, we found that gaps of different duration between CS termination and US onset in the two training phases resulted in less of a Hall-Pearce negative transfer effect than did an equivalent gap in the twotraining phases. The results are discussed with respect tothe temporal coding hypothesis (Matzel, Held, &Miller, 1988), the Pearce and Hall (1980) model, and Bouton's (1993) interference model.     

Motivation for Creativity in Design Students

The purpose was to study motivation for creativity in design students in the framework of the cognitive orientation theory which defines motivation as a function of beliefs of four types (about goals, norms, oneself and reality) concerning themes identified as relevant for creativity. It was hypothesized that scores of the four belief types would enable predicting creativity. The participants were 52 design students who were administered an actual design task and questionnaires: The Survey about Attitudes, Questionnaire about Designing and the Cognitive Orientation of Creativity (COQ-CR). The independent variables were the scores of the belief types based on the COQ-CR. The dependent variables were the evaluation of the creativity of the designs by four expert architects, and various variables based on self-evaluation of the students in the questionnaires referring to the design and designing process: fluency, flexibility, elaboration, fulfilling requirements, considering the context, having a central idea, meaningfulness of the task, involvement of feelings in designing, and handling constraints. Regression analyses showed that the majority of variables referring to creativity were predicted significantly by the predictors. The findings support the validity of the COQ-CR for assessing motivation for creativity and of the cognitive motivational approach to creativity.     

Effects of exposure of mice to hindlimb unloading on leukocyte subsets and sympathetic nervous system activity

The hindlimb unloading (HU) rodent model was developed to simulate some of the aspects of spaceflight conditions. Our previous studies showed that exposure to HU for 48 h (h) followed by bacterial challenge, reduces the ability of mice to resist infection. The purpose of this study was to investigate the physiological changes in mice during the 48 h of exposure to HU to understand the mechanisms involved in the increased susceptibility to infection observed in mice subjected to these conditions. Female Swiss Webster mice were hindlimb-unloaded during 48 h. Blood samples, spleen and peritoneal cells were removed before and after 18 or 48 h of HU-exposure. Leukocyte subset analysis was performed in spleen and peritoneal cells by flow cytometry, and catecholamine levels were measured in plasma and whole spleen by a catecholamine enzyme immunoassay. Catecholamine levels measured in plasma and spleen were significantly greater in mice exposed to HU compared to control. This increase coincided with significant reductions in spleen size in the HU group. Flow cytometric analyses showed a significant reduction of splenic CD19 + B-cells and NK1.1+ cells in mice exposed to HU with a concomitant increase in T-cells. These results suggest that exposure to HU increases the activity of the sympathetic nervous system (SNS) and induces lymphocyte sub-population changes that may contribute to the deregulation of immunity seen in mice exposed to HU and, more importantly may predispose the otherwise healthy host to the subsequent reduced ability to resist infections.