Most of the patients who participate in our research suffer from medically refractory epilepsy and have intracranial electrode implants to identify a region of the brain that can be resected in hopes of curing their seizures.
During patients' one- to two-week stay in the Epilepsy Monitoring Unit, they participate in a variety of experiments that allow us to study human cognition.
Restoring Active Memory Replay (RAM Replay)
RAM Replay is supported by DARPA, the Defense Advanced Research Projects Agency. The project investigates the role of neural “replay” in forming and recalling memory, to help people better recall episodic events and learned skills.
Our research team is working to develop a brain-computer interface that uses intracranial electrical stimulation to enhance memory in patients suffering from traumatic brain injury.
This multi-site initiative, uniting basic science and clinical research teams with bioengineering companies, places us at the forefront of neuroscience research.
Contributions of Parietal and Hippocampal Regions to Episodic Memory
Leveraging a unique neurosurgical electrode implant strategy, stereo encephalography (sEEG), we are investigating the contribution of various parietal brain structure to episodic memory encoding and retrieval.
We analyze patterns of oscillatory activity and the neural networks that give rise to successful memories and facilitate memory retrieval to identify the parietal regions that are engaged by human memory. These findings allow us to identify parameters of electrical stimulation including what brain regions to stimulate to try to enhance memory.
In addition, we are exploring the interaction between parietal and hippocampal brain regions during true and false memory encoding. We are also exploring the interactions between the anterior and posterior hippocampus during encoding and retrieval. This will allow us to better understand the processing of memory and the interaction between regions of the brain when forming memories.
Cortico-Cortical Evoked Potentials (CCEP)
In addition to our work using passive EEG recordings, we use active stimulation throughout the brain and evaluate the evoked response at other regions to evaluate patterns of structural connectivity.
We are analyzing this information along with fMRI data from the same participants. This data allows us to evaluate the relationship between structural and functional connectivity and to identify biomarkers of diseased brain tissue, such as epileptogenic neural networks.
We are working on understanding mathematical cognition. We are utilizing a large, multi-site database of intracranial EEG data to scan the entire brain for regions that selectively activate during math problem-solving. The functional contribution of each math-selective region is hypothesized by observing how the intra-region activity pans out across time and space. We are looking at the electrophysiological correlates while participants complete different math problems. We explore network connectivity during mathematical processing, and evaluate the patterns of oscillatory activity. This project furthers our understanding of human number sense, a fundamental cognitive process. It also contributes to knowledge necessary to design a closed-loop stimulation device to aid patients with dyscalculia.
Brain Function and Memory
We study how deep brain stimulation can disrupt brain function affecting human memory encoding and retrieval. I apply a multi-modal approach, combining functional magnetic resonance imaging (fMRI), quantitative MRI, intracranial EEG, and deep brain stimulation in epileptic patients, as well as myeloarchitectonic and cytoarchitectonic measurements in post-mortem brains to study cellular mechanisms underlying brain function and behavior.
Neural Basis of Preferences
We are working to decode the patterns of neural activity that give rise to human preferences and reward processing. This work is a more refined approach to reward processing than simply comparing the regions of the brain that are involved in processing positive and negative feedback.
This work may lay the foundation for using electrical stimulation to treat behavioral disorders, such as obesity and addiction, that are believed to arise from abnormal reward processing.