Our Research

We ask questions such as: How can we develop more realistic behavioral paradigms for stopping inappropriate response tendencies? What are the critical nodes in the human brain for behavioral response control? How are these nodes connected and how do they relay information? How can we change response control, through feedback (such as closed-loop)? How do deficits in response control in simple laboratory tasks relate to clinical impulse control disorders? How does stopping impact working memory? The lab has a particular focus on the prefrontal cortex and the basal ganglia. Some example projects are listed below.

The lab has coils for Transcranial Magnetic Stimulation and two kinds of EEG systems. Our MRI scanning is done at the UCSD fMRI center. We collaborate with clinician-scientists to study Parkinson’s patients, neurosurgical patients, and Tourette’s patients.  We also study response control in mice via a collaboration with UCSD Neurobiology.

Current funding is from the National Institutes of Health (NIDA, NINDS), the James S McDonnell Foundation and the Tourette’s Syndrome Association.

Current major collaborators are: Tom Hnasko PhD (UCSD); Nitin Tandon MD (UT Houston); Nader Pouratian MD PhD (UCLA); Joy Geng PhD (UC Davis); Robert Chen MD (Toronto Western Hospital)

research-1

Local Field Potential Recording in Parkinson’s Patients

The subthalamic nucleus of the basal ganglia appears to be an important node in wider fronto-basal-ganglia circuits for stopping action. With collaborators at Toronto Western Hospital in Canada we are recording from the subthalamic nucleus while patients perform simple tasks. See our recent publication here.

research-2

Response Control in Mice

Via a local collaboration with Hnasko lab at UCSD we are studying response control in mice. We take advantage of cutting edge tools in optogenetics, tracing and imaging to examine how the basal ganglia and cortex are engaged during simple tasks.

research-33

Probing the motor system using Transcranial Magnetic Stimulation

We often use TMS to deliver pulses over primary motor cortex and we then record the evoked response in particular muscles. When done during a task this provides high temporal resolution information about the activation and suppression of impending motor responses. Recently we developed a way of doing this in a real-time feedback loop, see here.

rsz_ecog

Electrocorticography studies of stopping action

With our colleagues at UT Houston Medical School we are studying epilepsy patients who have implanted intracranial electrodes. We thus acquire high spatiotemporal resolution information about different regions (and networks) of the brain We can also stimulate these electrodes during task performance, e.g. here and this news report.

rsz_1silvernew-2

Behavioral studies of devaluation

We have developed a behavioral paradigm in which rapid action stopping devalues a stimulus. We are currently trying to understand how this happens, and we are interested in whether it generalizes and whether we can make the effect stronger and lasting. This research direction has potential for disorders of stimulus over-valuation.

figurej

Human Cortex-Basal Ganglia Action Regulating Networks

We are participating in a multi-site UO1 Brain Initiative grant entitled: “Invasive Approach to Model Human Cortex-Basal Ganglia Action-Regulating Networks”. This involves simultaneous recording from cortex and basal ganglia in humans undergoing surgical procedures, and heralds a unique opportunity to learn about these circuits. For related ideas see here.