Research

1. Strategy use and structure learning

Subjects in many task show evidence of abrupt changes in behavior consistent with a sudden change in strategy. In many cases, these strategies clearly leverage subjects’ understanding of some statistical or structural regularity in the task, and so must involve some learning of the underlying task structure. There is a large body of evidence linking this kind of learning to prefrontal-hippocampal circuitry, which forms and updates a cognitive map of this structure. We have some evidence linking this .

2. Cognitive contributions to motor control

When acting in an uncertain environment, or when the action needed to achieve a goal is unknown, cognitive structures in the brain are engaged to analyze and decipher the problem’s structure, and dictate the parameters that the motor system uses to program the needed action. These processes are especially important in the early stages of learning, before the appropriate action has been decided upon, and the motor system can take over the process of adaptation. Most of my work uses neuroimaging methods to study functional interactions between motor and non-motor structures during this early stage of learning.

3. Methods for analyzing fMRI functional connectivity

The analysis of fMRI functional connectivity typically involves the analysis of very high-dimensional covariance matrices, encoding the BOLD signal covariance between brain regions or voxels. The most popular of these approaches, which I’ve used extensively in my imaging work, takes advantage of the Riemannian-manifold structure of the space of covariance matrices.