Caterina Gratton

At every waking moment the human brain absorbs information, selectively filters it, and integrates it into perceptions and memories to achieve goals. These processes rely on the unique functions of individual regions of the brain, as well as on coordinated activity across regions organized into large-scale networks. How these multi-scale processes are coordinated remains an enigma. My lab characterizes how human brain networks are organized and how they contribute to the multitude of goal-directed behaviors humans can complete. Furthermore, we examine how these processes break down with damage and disease. Our work addresses these questions through three interrelated lines of research on (1) large-scale networks and hubs, (2) the role of top-down control systems, and (3) top-down modulation of visual processing.

To answer these questions, we use a multifaceted approach with complementary methods to (i) track the spatial and dynamic characteristics of brain activity (via functional magnetic resonance imaging [fMRI] and electroencephalography [EEG]), and (ii) manipulate and quantify perturbation of brain systems (via transcranial magnetic stimulation [TMS], recordings from neurological patients, and pharmacological manipulations). We employ sophisticated analysis techniques to provide a quantitative description of brain function, using functional connectivity and graph theoretical measures to characterize brain networks, and encoding models to characterize functional selectivity within brain regions. This broad toolkit enables us to address novel systems-level questions about the organization of human brain networks, their role in top-down control, and how they break down with damage.

Networks & hubs: Our laboratory is interested in developing a better understanding of functional brain networks and how network organization is maintained and dynamically altered in goal-directed contexts. We study how network organization and hubs contribute to brain function and behavior, especially in the context of different tasks and damage. In this research we use graph theoretical techniques to define brain networks and identify specialized hub regions within them. This research provides important groundwork on the behavioral relevance of functional network organization and brain hubs. This foundation will not only inform the study of basic brain mechanisms but will also provide potential therapeutic targets for future translational research.

Top-down control systems: Our second line of research investigates the organization and roles of the frontoparietal and cinguloopercular networks. Both networks have been linked with cognitive control (the ability to override prepotent responses in the service of higher-level goals). These networks are often co-activated but it remains unclear how these two networks contribute to goal-directed behavior, and whether they interact in different contexts. This line of work will help to elucidate the multi-network organization for control in the human brain, and the respective roles of each functional system and sub-regions within these systems.

Top-down modulation of vision: Our final line of research examines the interaction between top-down control systems and how visual representations are altered with attention. One goal is to unite these two distinct levels of interrogation to understand the connection between control mechanisms used at a local and network level to selectively enhance the processing of relevant information.