1. Control Processes Involved in Executive Function (P.I. Banich)
How do we keep a goal in mind? How do we inhibit behavior?
The goal of this project is to utilize behavioral, brain mapping, and computational modeling methods to examine the neural mechanisms involved in cognitive control, which include processes requiring the selection, manipulation, inhibition, and evaluation of information actively being maintained to meet task demands. A network of brain regions including the anterior cingulate cortex, dorsal lateral prefrontal cortex, and posterior parietal cortex has been identified by the P.I.'s laboratory and others as important for these aspects of attentional control (Banich et al., 2000a, 2000b; Barch et al., 1997; Botvinick et al., 2001; Carter et al., 1998; Garavan, Ross, & Stein, 1999; MacDonald, Cohen, Stenger, & Carter, 2000; Milham & Banich, 2005; Milham et al., 2001). Our project tests the validity of the P.I.'s model derived from studies of cognitive control using fMRI and the Stroop task. We do so broadly, adding the expertise of individuals using event-related brain potential (ERP) methods as well as a leading figure in computational modeling, enabling a multifaceted test of the model.
2. Learning Process That Support Executive Function (P.I. O'Reilly)
What ways of learning aid in executive function?
Our uniquely human executive function abilities emerge slowly over a protracted period through late adolescence, closely tracking the development of the PFC (Diamond & Goldman-Rakic, 1989; Huttenlocher, 1990; Casey, Giedd, & Thomas, 2000). Our project is interested in what develops during this time, and how does it support executive function. We hypothesize that this protracted period of development allows for the learning of a systematic vocabulary of representations in the prefrontal cortex and associated brain areas to produce abstract, rule-like representations in prefrontal cortex, which then supposrt better generalization to novel task contexts (Rougier, Noelle, Braver, Cohen, & O'Reilly, 2005). We further argue that workin memory function depends critically on dopamine-mediated mechanisms in the basal ganglia, that then modulate the updating and maintenance of information in prefrontal cortex (O'Reilly & Frank, 2006; Frank, Seeberger, & O'Reilly, 2004). This project addresses issues that are central to the three major center questions, which focus on the nature of executive function representations, and the neural systems in the PFC and other areas, with linkages across computational, psychological, and neurobiological levels of analysis.
3. Emotional Influences on Executive Processes (P.I. Heller)
How does mood or personality influence executive function?
Executive funtion (EF) has been strongly associated with positive affect, which appears to enhance performance on a wide range of tasks (e.g. Herrington et al., 2005). Depression, in contrast, seems to impair performance on tasks that require EF (for review, see Mohanty & Heller, 2002; Levin, Heller, & Miller, in press; von Hecker & Meiser, 2005). We have argued that different emotions are associated with changes in regional brain activity that either enhance or impair performance, depending on the role that a particular brain region plays in a task (for review, see Heller, Koven, & Miller, 2003; Compton et. al., 2003). Furthermore, we and others have proposed potential mechanisms that may mediate these effects (e.g., Nitschke, Heller, & Miller, 2000; Ashby et al., 1999). To date, there has been no systematic evaluation of the impact of specific emotional states on EF, nor has there been an assessment of the regional brain activity involved. In addition, research into the mechanisms involved has only just begun. This project, based at the University of Illinois, aims to apply our well established model of brain organization in emotion to an investigation of EF using the computational modeling techniques and models of EF that have been extensively investigated by colleagues at the University of Colorado. This integration of theory and technique across several groups of researchers has the potential to identify the relationships among different types of emotions and different EF subcomponents as well as to discover the mechanisms of these effects.
4. Genetics (P.I. Friedman)
What aspects of executive function are inherited?
The broad goal of this project is to use molecular genetic analyses in concert with computational modeling to begin to specify in more detail how the DA system regulates three correlated but separable EF components - inhibiting prepotent responses, updating working memory, and shifting mental sets (hereafter inhibiting, updating, and shifting). The primary dataset uses existing data on approximately 814 individual twins who were tested on nine index EF tasks (three for each EF compnent) at age 17 and were also tested on general cognitive ability and IQ at age 16. Our multivariate genetic and environmental confirmatory factor analyses of these data indicate that the three EF components, measured as latent variables, are highly heritable. Moreover, individual differences in these three functions reflect both common genetic factors and genetic factors unique to the factors, and both the common and unique factors are somewhat independent from the genetic factors influencing general intelligence. Hence, we already know the underlying genetic and environmental structure of these three EF componenets. This project takes the important next step of specifying how different DA - related genes influence both the common and unique variance in EF components.
5. Representations Supporting Executive Control and its Development (P.I. Munakata)
How does executive function develop and change during childhood?
The primary aim of this project is to investigate the representations and processes underlying executive control and its development during childhood. Our research investigates the hypothesis that critical developments are linked to two processes that rely on prefrontal cortical developments: the emergence of increasingly abstract, rule-like representations and increasing abilities to maintain information in an active form. Our previous work with children and neural network models found that adaptive responses are associated with both more abstract and more active representations of task-relevant information. Our study builds on this work and results from other labs to directly test the role of abstract and active representations in executive control and its development. These issues are investigated through behavioral studies with children, neuroimaging studies with adults, and neural network models tested at different points in development. This approach allows us to better understand not onl the important relations among abstract representations, active representations, and executive control, but also how these relations and methods for bootstrapping executive control emerge across development. The neuroimaging and correspondign neural network studies allow us to test hypotheses about the neural compnents associated with representations supporting executive control. These studies will ultimately inform the development of novel tasks for use in children.
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