Click any of the tabs above to find out more about our research methods. Below is an overview of the current set of ongoing projects in the lab.

In an effort to further our understanding of brain systems, our research focuses on deciphering the functions of neural circuits linking frontal cortex with basal ganglia in cognitive processes such as learning, memory, decision making, and cognitive control. Such an understanding can provide insights into how these functions are altered by neurological and psychiatric conditions known to involve neurochemical and/or structural changes to this circuitry.

Because the underlying brain mechanisms are complex, we make use of computer simulations as a tool for theory building which allows us to explore dynamics among the multiple brain systems involved, as constrained by anatomical, physiological and functional data in the literature. The computer models are then put to the test with empirical experiments using a variety of methods: patient studies, electroencephalography, pharmacology, genetics, deep brain stimulation, and intracranial recordings. Such experiments can help us determine whether our theoretical models are plausible, and can be used to refine the models if/when they are not.

The LNCC is currently working with Parkinson's Disease patients on different types of treatments, including D2 agonist, Levodopa/Carbidopa medication and Deep Brain Stimulation, to investigate the role of the basal ganglia dopaminergic pathways in learning and decision making. Computer modeling of the basal ganglia dopamine system and its involvement in cognition has been useful for understanding medication effects and for making novel predictions regarding core cognitive deficits in PD. We supplement these investigations with EEG in order to investigate event-related potentials and oscillatory synchronization using time-frequency analysis.

Interactions between Rule-Based and Implicit Learning Systems
We are currently exploring how prior explicit knowledge, instructions, or rules interact with the implicit reinforcement learning system of the basal ganglia. Our computational and behavioral work has suggested that explicit verbal information either biases the way the basal ganglia learns from experience, or allows such learning to proceed unbiased but overrides it to control behavior. Currently, we are investigating the potential role of DA genes in this type of learning.

Higher Level Cognitive Functions
The basal ganglia are not only involved in learning and decision making, but also multiple aspects of executive function, including working memory and inhibitory control, via interactions with different parts of prefrontal cortex.

Working Memory
Our models and empirical data suggest that parts of the basal ganglia are involved in determining when and when not sensory information should be updated into prefrontal cortical working memory representations. The circuits involved in such processes can also interact with and shape decisions made by the "lower-level" motor circuits. We are currently working on a hierarchical model of cognitive control in which anterior prefrontal cortex can provide contextual information to shape how information in more posterior circuits is processed, which in turn can influence processing in the motor circuit.

Inhibitory Control
We are working on a project regarding response inhibition in executive control. To do this, we extend our network model of the basal ganglia to include a frontal pathway and its innervation by phasic norepinephrine signals, which together can pause and override the
basal ganglia action selection mechanism.