Funded Grants

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Grantee: Washington University, USA

Researcher: Kathleen McDermott

Grant Title: Cognitive Processing in Inferior Frontal Gyrus: Beyond the Verbal/Nonverbal Heuristic

Program Area: McDonnell-Pew Program in Cognitive Neuroscience

Grant Type: Research Award

Year Awarded: 1999

Cognitive Processing in Inferior Frontal Gyrus: Beyond the Verbal/Nonverbal Heuristic

The goal of this project is to use newly-developed event-related functional magnetic resonance imaging (fMRI) techniques to further understanding of the functional organization of the human brain. The experiments will build upon a long-standing tradition in the neuropsychological literature of attempting to characterize differences in processing style for the left and right hemispheres. Specifically, the goal of this project is to add precision to the characterization of processes underlying hemispheric asymmetries that have recently been demonstrated in a specific region of frontal cortex: the posterior and dorsal extent of inferior frontal gyrus (in or near BA 6/44). Thus far, the heuristic invoked for explaining these effects has been that left-lateralized activation seems to be elicited by verbal processing, whereas right-lateralized activation seems to be elicited by nonverbal processing (Kelley, et al., 1998; Wagner, et al., 1998).

Although the verbal/nonverbal heuristic fits well with the data at a general level (and with the literature at large), it is not particularly descriptive: The cognitive psychological literature is rich with distinctions within both of these domains. For example, verbal processing can be orthographic, phonological, lexical, associative, or semantic in nature (to name a few of the processes that can go into mental manipulation of verbal information). Similarly, nonverbal processing can be subdivided into many component processes. The primary goal of this project is to more adequately specify some of the cognitive processes that affect level of activation (and degree of laterality) in inferior frontal cortex. These experiments will allow us to move beyond vague dichotomies into a more complete understanding of the cognitive components affecting one of the most robustly activated regions with respect to higher level cognitive function in frontal cortex.

With these goals in mind, there are two specific aims in this proposal, which center around the goal of gaining a better understanding of the high level cognitive activations seen in inferior frontal gyrus:

  1. To identify the specific component processes currently characterized by the "verbal processing" label, which underlie activity in left inferior frontal gyrus.
  2. To explore the specific component "nonverbal" processes underlying activity in right inferior frontal gyrus.

These experiments should enhance our understanding of hemispheric asymmetries and pave the way for new theories regarding the neural substrates of cognitive function.