Mapping of olfactory memory circuits: region-specific c-fos activation after odor-reward associative learning or after its retrieval

Although there is growing knowledge about intracellular mechanisms underlying neuronal plasticity and memory consolidation and reconsolidation after retrieval, information concerning the interaction among brain areas during formation and retrieval of memory is relatively sparse and fragmented. Addressing this question requires simultaneous monitoring of activity in multiple brain regions during learning, the post-acquisition consolidation period, and retrieval and subsequent reconsolidation. Immunoreaction to the immediate early gene c-fos is a powerful tool to mark neuronal activation of specific populations of neurons. Using this method, we are able to report, for the first time, post-training activation of a network of closely related brain regions, particularly in the frontal cortex and the basolateral amygdala (BLA), that is specific to the learning of an odor-reward association. On the other hand, retrieval of a well-established associative memory trace does not seem to differentially activate the same regions. The amygdala, in particular, is not engaged after retrieval, whereas the lateral habenula (LHab) shows strong activation that is restricted to animals having previously learned the association. Although intracellular mechanisms may be similar during consolidation and reconsolidation, this study indicates that different brain circuits are involved in the two processes, at least with respect to a rapidly learned olfactory task.     

Effects of task performance and contextual performance on systemic rewards

Evidence from 2 samples of Air Force mechanics supported the hypothesis that contextual performance affects employees' career advancement and rewards over time. Results of hierarchical regressions controlling for experience showed task performance and contextual performance each predicted systemic rewards. Each facet explained separate variance in promotability ratings over 2 years. In both samples, contextual performance explained separate variance in informal rewards but task performance did not. Task performance explained incremental variance in career advancement 1 year later but contextual performance did not. Analyses using correlations corrected for unreliability suggest these results cannot be attributed to measurement error. Contextual performance still explained separate variance in informal rewards, and task performance explained distinct variance in career advancement a year later.     

Additional study of the Youth-Depression Adjective Check List

Replicated and extended aspects of determinations of reliability and validity for the State version of the Youth-Depression Adjective Check List. Students from Grades 9 through 12 (64 girls and 41 boys) completed the State version and the Adolescent Activities Checklist on each of 12 consecutive days and completed the Trait version, the Reynolds Adolescent Depression Scale, the Multiple Affect Adjective Check List--Revised Grade 6, and the Adolescent Activities Checklist at the beginning and the end of the study. Good reliability and validity of the State version were confirmed and extended, and preliminary information on characteristics of the Trait version of the Youth-Depression Adjective Check List also was presented. The State version seems suitable for use in research with adolescents and preadolescents. More study of the Trait version is recommended.     

A comparison of two response time models applied to perceptual matching

Two models, a Poisson race model and a diffusion model, are fit to data from a perceptual matching task. In each model, information about the similarity or the difference between two stimuli accumulates toward thresholds for either response. Stimulus variables are assumed to influence the rate at which information accumulates, and response variables are assumed to influence the level of the response thresholds. Three experiments were conducted to assess the performance of each model. In Experiment 1, observers performed under different response deadlines; in Experiment 2, response bias was manipulated by changing the relative frequency ofsame anddifferent stimuli. In Experiment 3, stimulus pairs were presented at three eccentricities: foveal, parafoveal, and peripheral. We examined whether the race and diffusion models could fit the response time and accuracy data through changes only in response parameters (for Experiments 1 and 2) or stimulus parameters (for Experiment 3). Comparisons between the two models suggest that the race model, which has not been studied extensively, can account for perceptual matching data at least as well as the diffusion model. Furthermore, without the constraints on the parameters provided by the experimental conditions, the diffusion and the race models are indistinguishable. This finding emphasizes the importance of fitting models across several conditions and imposing logical psychological constraints on the parameters of models.     

Minimal information to determine affine shape equivalence

Participants judged the affine equivalence of 2 simultaneously presented 4-point patterns. Performance level (d') varied between 1.5 and 2.7, depending on the information available for solving the correspondence problem (insufficient in Experiment 1a, superfluous in Experiment 1b, and minimal in Experiments 1c, 2a, 2b) and on the exposure time (unlimited in Experiments 1 and 2a and 500 ms in Experiment 2b), but it did not vary much with the complexity of the affine transformation (rotation and slant in Experiment 1 and same plus tilt in Experiment 2). Performance in Experiment 3 was lower with 3-point patterns than with 4-point patterns, whereas blocking the trials according to the affine transformation parameters had little effect. Determining affine shape equivalence with minimal-information displays is based on a fast assessment of qualitatively or quasi-invariant properties such as convexity/ concavity, parallelism, and collinearity.     

Ratings of emotion in laterally presented faces: sex and handedness effects

Sixteen right-handed participants (8 male and 8 female students) and 16 left-handed participants (8 male and 8 female students) were presented with cartoon faces expressing emotions ranging from extremely positive to extremely negative. A forced-choice paradigm was used in which the participants were asked to rate the faces as either positive or negative. Compared to men, women rated faces more positively, especially in response to right visual field presentations. Women rated neutral and mildly positive faces more positively in the right than in the left visual field, whereas men rated these faces consistently across visual fields. Handedness did not affect the ratings of emotion. The data suggest a positive emotional bias of the left hemisphere in women.     

Cardiovascular responses to open-field stress in rats: sex differences and effects of gonadal hormones

We studied sex differences in cardiovascular responses to stress using a new radio-telemetry model in which freely-moving Spontaneously Hypertensive rats (SHR) are exposed to open-field novelty stress. This model allowed simultaneous assessment of cardiovascular and behavioural responses to psychological stress. Female SHR in the diestrous stage of their estrous cycle had markedly greater pressor and tachycardic responses to open-field exposure when compared to either female rats not in diestrous or male SHR. Treatment of ovariectomized SHR with estrogen alone had no significant effect on cardiovascular reactivity, while a combined treatment of estrogen and progesterone slightly, but significantly attenuated their pressor response to open-field stress. In addition, treatment of castrated male rats with testosterone significantly enhanced their pressor responses to stress when compared to values obtained before treatment. None of the hormone treatments had any significant effect on heart rate responses to stress. Neither at different stages of the estrous cycle nor after hormone treatments were there any marked changes in behavioural responses in the open-field, making it unlikely that the differences in cardiovascular stress responses were caused by changes in behavioural activity. These data demonstrate differences in cardiovascular stress responses that seem to be dependent on the stage of the estrous cycle. They suggest that particularly androgens, such as testosterone, may enhance pressor responses to stress. On the other hand, a combination of estrogen and progesterone, rather than estrogen alone, may have a small attenuating effect on cardiovascular reactivity.     

A psychometric evaluation of the social skills rating system in children with attention deficit hyperactivity disorder

The social skills rating system (SSRS) was developed to assess social skills of children, as observed by multiple raters (teacher, parent, child). Studies of the SSRS have been conducted with handicapped, mentally retarded and learning disabled children. No studies have reported the psychometric properties of the SSRS in a clinical ADHD sample. This is important, because deficient social functioning is associated with ADHD. The present study assesses the psychometric properties of the teacher, parent and child versions of the SSRS in children with ADHD (n = 123), and normal controls (n = 239). Also, the social skills of children with ADHD, as rated on the SSRS were examined. Results support the factor structure and internal consistency of the original SSRS-teacher version. Moreover, support was found for 3 out of 4 scales of the SSRS-parent version. The factor structure of the SSRS-child version could not be replicated. An explanatory factor analysis on the SSRS-child version yielded two factors. Evidence was found for discriminative ability of the SSRS between normal controls and children with ADHD. Finally, informant agreement between raters was found to be poor.