Fighting experiences and natural killer cell activity in male laboratory mice

There is currently much interest in the potential impact of psychological factors on immune responses. An attempt was made to assess the effects of dominant/subordinate polarity in male mice on the cytotoxic activities of their natural-killer (NK) cells. On the basis of repeated agonistic encounters, categories of subordinate and dominat animals were selected. These animals were compared with manipulated controls (introduced to a novel test cage without an opponent on each occasion) and undisturbed controls (who remained in isolation without manipulation). In terms of NK activity, immunosuppression was observed in both dominant and subordinate categories when compared to undisturbed controls. There were, however, no differences between the fighting exposed subjects and the manipulated controls, suggesting that stress accounts for any changes. © 1994 Wiley-Liss, Inc.     

Processing coordinated structures: incrementality and connectedness

We recorded participants' eye movements while they read sentences containing verb-phrase coordination. Results showed evidence of immediate processing disruption when a reflexive pronoun embedded in the conjoined verb phrase mismatched the sentence subject. We argue that this result is incompatible with models of human parsing that employ only bottom-up parsing procedures, even when flexible constituency is employed. Models need to incorporate a mechanism similar to the adjoining operation in Tree-Adjoining Grammar, in which one structure is inserted into another.     

On Modal μ-Calculus and Non-Well-Founded Set Theory

A finitary characterization for non-well-founded sets with finite transitive closure is established in terms of a greatest fixpoint formula of the modal -calculus. This generalizes the standard result in the literature where a finitary modal characterization is provided only for wellfounded sets with finite transitive closure. The proof relies on the concept of automaton, leading then to new interlinks between automata theory and non-well-founded sets.     

The Mechanisms of Space‐Time Association: Comparing Motor and Perceptual Contributions in Time Reproduction

The spatial‐temporal association indicates that time is represented spatially along a left‐to‐right line. It is unclear whether the spatial‐temporal association is mainly related to a perceptual or a motor component. In addition, the spatial‐temporal association is not consistently found using a time reproduction task. Our rationale for this finding is that, classically, a non‐lateralized button for performing the task has been used. Using two lateralized response buttons, the aim of the study was to find a spatial‐temporal association in a time reproduction task. To account for the perceptual component, reference and target stimuli were presented in different spaces through four experiments. In all experiments, a Spatial‐Temporal Association of Response Codes (STEARC) effect was found and this effect was not modulated by the spatial position of both reference and target stimuli. The results suggested that the spatial‐temporal association was mainly derived from the spatial information provided by response buttons, reflecting a motor but not visuospatial influence.     

Memory for symmetry and perceptual binding in patients with schizophrenia

The present study investigated the use of perceptual binding processes in schizophrenic (SC) patients and matched healthy controls, by examining their performance on the recall of symmetrical (vertical, horizontal and diagonal) and asymmetrical patterns varying in length between 2 and 9 items. The results showed that, although SC patients were less accurate than controls in all conditions, both groups recalled symmetrical patterns better than asymmetrical ones. The impairment of SC patients was magnified with supra-span symmetrical arrays, and they were more likely to reproduce symmetrical patterns as asymmetrical, particularly at medium and high length levels. Hierarchical regression analyses further indicated that the between-group differences in the recall of supra-span vertical and horizontal arrays, which require a greater involvement of visual pattern processes, remained significant after removing the variance associated with performance on asymmetrical patterns, which primarily reflects intrafigural spatial processes. It is proposed that schizophrenia may be associated with a specific deficit in the formation and retrieval of the global visual images of studied patterns and in the use of the on-line information about the type of symmetry being tested to guide retrieval processes.     

Perceptual and motor congruency effects in time–space association

It is well established that temporal events are represented on a spatially oriented mental time line from left to right. Depending on the task characteristics, the spatial representation of time may be linked to different types of dimensions, including manual response codes and physical space codes. The aim of the present study was to analyze whether manual response and physical space codes are independent of each other or whether they interact when both types of information are involved in the task. The participants performed a temporal estimation task with two lateralized response buttons in four experiments. In the first experiment, the target stimuli were presented on the left side, at the center, or on the right side of the space, whereas the reference stimuli were always presented centrally. The reverse situation was presented in the second experiment. In the third experiment, both stimuli were presented in opposite spatial positions (e.g., left–right), whereas in the last experiment, both stimuli were presented in the same spatial position (e.g., left–left). In all experiments, perceptual and motor congruency effects were found, but no modulation of the congruency effects was found when both the perceptual and motor components were congruent. The results indicated that physical, spatial, and manual response codes are independent from each other for time–space associations, even when both codes are involved in the task. These results are discussed in terms of the “intermediate-coding” account.     

MATERNAL SELF‐REPORTED DEPRESSIVE SYMPTOMS AND MATERNAL CORTISOL LEVELS INTERACT TO PREDICT INFANT CORTISOL LEVELS

Three basic findings have emerged from research on maternal depressive symptoms and offspring hypothalamic–pituitary–adrenal functioning: (a) Mothers’ depressive symptoms are positively associated with their offsprings’ cortisol stress response, (b) numerous individual and interpersonal maternal characteristics moderate this association, and (c) maternal and infant cortisol levels are highly correlated. In combination, these findings have suggested that maternal cortisol levels may moderate the relation between maternal depressive symptoms and infant cortisol responsivity; the current study assessed this hypothesis. Participants were 297 mother–infant dyads who were recruited from the community. Maternal depressive symptoms were assessed via self‐report. Dyads participated in two differentially stressful infant challenges when infants were 16 and 17 months old. Mother and infant salivary cortisol was collected before and after challenges. Results indicate that maternal cortisol levels moderated associations between maternal depressive symptoms and infant cortisol levels across both challenges. Infants showed higher cortisol levels if their mothers had both higher depressive symptoms and higher cortisol levels, as compared to infants of mothers with higher depressive symptoms and lower cortisol, and to infants of mothers with lower depressive symptoms and either higher or lower cortisol levels. We discuss findings in relation to environmental and biological factors that may contribute to the intergenerational transmission of depressive symptoms.     

Memory for object location: a span study in children.

The aim of the present study was to analyze the developmental changes in three spatial processes, namely, in positional reconstruction involving the retention of spatial locations per se (Positional encoding task), in the assignment of objects to positions (Object-to-position assignment task), and in the integration of these two (Combined task). A span procedure was used to assess the development of spatial memory in children aged 6, 8, and 10 years tested in these three tasks. The findings of the present study provide developmental spans for each relocation task. Results show an age-dependent improvement in all tasks, suggesting that spatial position is not automatically encoded. The results also show different developmental patterns for the relocation tasks considered, suggesting that spatial memory comprises a number of different component processes.