Using FMRI to test models of complex cognition

This article investigates the potential of fMRI to test assumptions about different components in models of complex cognitive tasks. If the components of a model can be associated with specific brain regions, one can make predictions for the temporal course of the BOLD response in these regions. An event-locked procedure is described for dealing with temporal variability and bringing model runs and individual data trials into alignment. Statistical methods for testing the model are described that deal with the scan-to-scan correlations in the errors of measurement of the BOLD signal. This approach is illustrated using a "sacrificial" ACT-R model that involves mapping 6 modules onto 6 brain regions in an experiment from Ravizza, Anderson, and Carter (in press) concerned with equation solving. The model's visual encoding predicted the BOLD response in the fusiform gyrus, its controlled retrieval predicted the BOLD response in the lateral inferior prefrontal cortex, and its subgoal setting predicted the BOLD response in the anterior cingulate cortex. On the other hand, its motor programming failed to predict anticipatory activation in the motor cortex, its representational changes failed to predicted the pattern of activity in the posterior parietal cortex, and its procedural component failed to predict an initial spike in caudate. The results illustrate the power of such data to direct the development of a theory of complex problem solving, both at the level of a specific task model as well as at the level of the cognitive architecture.     

Young German children's early syntactic competence: a preferential looking study

Using a preferential looking methodology with novel verbs, Gertner, Fisher and Eisengart (2006) found that 21-month-old English children seemed to understand the syntactic marking of transitive word order in an abstract, verb-general way. In the current study we tested whether young German children of this same age have this same understanding. Following Gertner et al. (2006), one group of German children was tested only after they had received a training/practice phase containing transitive sentences with familiar verbs and the exact same nouns as those used at test. A second group was tested after a training/practice phase consisting only of familiar verbs, without the nouns used at test. Only the group of children with the training on full transitive sentences was successful in the test. These findings suggest that for children this young to succeed in this test of syntactic understanding, they must first have some kind of relevant linguistic experience immediately prior to testing--which raises the question of the nature of children's linguistic representations at this early point in development.     

Cultural Background and Individualistic–Collectivistic Values in Relation to Similarity, Perspective Taking, and Empathy

A path model testing antecedents and consequences of perceived similarity was examined for Asian and European Australian participants ( N  = 240). Cultural background and values were measured, and participants read scenarios describing a target in distress acting according to individualistic or collectivistic values. Consistent with past research, feeling similar to the target was linked to perspective taking and empathy. Moreover, Asian participants were more collectivistic, and collectivistic values were linked to higher empathy. In the present data, however, both endorsed higher levels of collectivism than individualism; individualism scores were equal; and the two values were positively correlated. Moreover, neither cultural background nor values were consistently linked to similarity. Implications are discussed for research on cultural background, values, and social interactions.     

Effects of repetitive stress during the acute phase of Trypanosoma cruzi infection on chronic Chagas' disease in rats

The effect of repetitive stress during acute infection with Trypanosoma cruzi (T. cruzi) on the chronic phase of ensuing Chagas' disease was the focus of this investigation. The aim of this study was to evaluate in Wistar rats the influence of repetitive stress during the acute phase of infection (7 days) with the Y strain of T. cruzi on the chronic phase of the infection (at 180 days). Exposure to ether vapor for 1 min twice a day was used as a stressor. Repetitive stress enhanced the number of circulating parasites and cardiac tissue disorganization, from a moderate to a severe diffuse mononuclear inflammatory process and the presence of amastigote burden in the cardiac fibers. Immunological parameters revealed that repetitive stress triggered a reduced concanavalin A induced splenocyte proliferation in vitro with major effects on the late chronic phase. Serum interleukin-12 concentration decreased in both stressed and infected rats in the early phase of infection although it was higher on 180 days post-infection. These results suggest that repetitive stress can markedly impair the host's immune system and enhance the pathological process during the chronic phase of Chagas' disease.     

Emotional irritation before mental stress is associated with enhanced peripheral norepinephrine

Research suggests equivocal findings on associations of catecholamines and mood. Our study investigated the associations of emotional state, blood pressure and catecholamines in 55 healthy males undergoing mental stress. We especially checked the reported link between norepinephrine (NE) and emotional irritation. Blood pressure (SBP, DBP) and heart rate (HR) were continuously monitored. NE and epinephrine (EPI) were measured before, after, and 20 minutes after stress. Participants were divided into irritated versus non-irritated and anxious versus non-anxious subjects by median split on their baseline questionnaires. The task elicited significant cardiovascular, hormonal, and psychological stress responses. NE levels were significantly correlated with irritation before stress. Irritated subjects showed significantly higher DBP and NE than non-irritated subjects. The higher NE and DBP levels in the irritated participants suggest detrimental psycho-physiological interrelations promoting the development of stress-mediated cardiovascular diseases. Heightened emotional irritation before stress may be regarded as a psychological risk factor.     

Stereotype change and prejudice reduction: short‐ and long‐term evaluation of a cross–cultural awareness programme

The present study reports an evaluation of an applied prejudice reduction intervention. Previous research has indicated that such programmes achieve limited success. The programme evaluated was an in‐house anti‐racist education programme aimed at reducing prejudice towards Aboriginal Australians. The target audience were employees of a large public service organization. Knowledge of, prejudice towards, and stereotyping of Aboriginal Australians were assessed before commencing the programme to establish a baseline. Changes in these variables were assessed immediately after completing the programme, and again 3 months after completing the programme. The programme had pronounced effects immediately after completion: there was a significant increase in knowledge and significant decrease in prejudice and negative stereotyping. However, 3 months later, there was no significant difference to baseline levels of prejudice and stereotyping. Knowledge remained significantly higher than at baseline 3 months after completing the programme. High prejudice participants alone experienced a significant, long‐term decrease in old‐fashioned racism. It is concluded that further research must be done to develop more successful strategies of prejudice reduction and stereotype change that are also applicable to ‘real world’ contexts. Copyright © 2001 John Wiley & Sons, Ltd.     

Unique Associations between Childhood Temperament Characteristics and Subsequent Psychopathology Symptom Trajectories from Childhood to Early Adolescence

Existing research suggests that temperamental traits that emerge early in childhood may have utility for early detection and intervention for common mental disorders. The present study examined the unique relationships between the temperament characteristics of reactivity, approach-sociability, and persistence in early childhood and subsequent symptom trajectories of psychopathology (depression, anxiety, conduct disorder, and attention-deficit hyperactivity disorder; ADHD) from childhood to early adolescence. Data were from the first five waves of the older cohort from the Longitudinal Study of Australian Children (n = 4983; 51.2% male), which spanned ages 4–5 to 12–13. Multivariate ordinal and logistic regressions examined whether parent-reported child temperament characteristics at age 4–5 predicted the study child’s subsequent symptom trajectories for each domain of psychopathology (derived using latent class growth analyses), after controlling for other presenting symptoms. Temperament characteristics differentially predicted the symptom trajectories for depression, anxiety, conduct disorder, and ADHD: Higher levels of reactivity uniquely predicted higher symptom trajectories for all 4 domains; higher levels of approach-sociability predicted higher trajectories of conduct disorder and ADHD, but lower trajectories of anxiety; and higher levels of persistence were related to lower trajectories of conduct disorder and ADHD. These findings suggest that temperament is an early identifiable risk factor for the development of psychopathology, and that identification and timely interventions for children with highly reactive temperaments in particular could prevent later mental health problems.     

The Art of Buying: Coming to Terms with Money and Materialism

Money and possessions hold strong attractions, but being driven to acquire them in order to enhance one's social standing is associated with lowered well-being. Literatures on money and happiness, materialism, and cultural mediators are reviewed. Consumer well-being is associated with being neither very tight nor very loose with money, with having relatively low financial aspirations, and with being low in materialism. Price-related behaviors – whether to spend low, spend high, or attempt to maximize value – are ways of responding to economic outlay vis-à-vis material wants, and these "strategies" offer a window into broader consumer lifestyles: the Value Seeker type is tight with money and materialistic; the Big Spender is loose with money and materialistic; the Non-Spender is tight with money and not materialistic; and the Experiencer is loose with money and not materialistic. Each of these types is described in terms of the potentials for well-being as well as the risks. Intrinsic motivation emerges as a key to well-being. This revised version was published online in August 2006 with corrections to the Cover Date.     

Age-dependent glutamate induction of synaptic plasticity in cultured hippocampal neurons

A common denominator for the induction of morphological and functional plasticity in cultured hippocampal neurons involves the activation of excitatory synapses. We now demonstrate massive morphological plasticity in mature cultured hippocampal neurons caused by a brief exposure to glutamate. This plasticity involves a slow, 70%-80% increase in spine cross-section area associated with a significant reduction in the width of dendrites. These changes are age dependent and expressed only in cells >18 d in vitro (DIV). Activation of both NMDARs and AMPARs as well as a sustained rise of internal calcium levels are necessary for induction of this plasticity. On the other hand, blockade of network activity or mGluRs does not abolish the observed morphological plasticity. Electrophysiologically, a brief exposure to glutamate induces an increase in the magnitude of EPSCs evoked between pairs of neurons, as well as in mEPSC frequency and amplitude, in mature but not young cultures. These results demonstrate an age-dependent, rapid and robust morphological and functional change in cultured central neurons that may contribute to their ability to express long term synaptic plasticity.