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Research Overview

A number of clinical interventions require insertion of invasive electrodes to monitor brain electrical activity with high anatomical and temporal precision. These include stereotactic EEG (sEEG) and electrocorticography (ECoG) for intractable epilepsy, and deep-brain stimulation (DBS) for epilepsy and movement disorders. These interventions provide a unique opportunity to record electrical brain activity with high signal to noise and temporal resolution, and to study the electrophysiological basis of human behavior. The results of this research will help us understand the neural basis of human behavior and shed light in related pathologies such as impulsivity and depression. In collaboration with the Neuromodulation group.

Lesion Studies

Focal brain lesions arising as a consequence of traumatic brain injury, ischemic stroke, intracerebral hemorrhages or surgical tumor resection provide an opportunity to examine the contribution of individual brain areas to behavior and cognition. We carry out behavioral testing of patients with focal lesions to study the function of a variety of brain areas, including prefrontal cortex and striatum. The results of this research will help us understand the behavioral deficits associated with distinct pathologies and the causal contribution of individual brain regions to behavior. In collaboration with the Neurotrauma group.

Computational Studies of Cognition

To study behavior in a reproducible and quantifiable way, we use a combination of behavioral tasks (decision-making games) and computational modeling. The lab is primarily focused on processes related to choice: how we assign value to and choose from different available options, how we learn from past actions and their consequences, and how these impact our mood. We frequently employ reinforcement learning (RL) models in combination with decision-making tasks in which subjects make choices under conditions of uncertainty, during learning and in social contexts.

Selected Publications: 

Encoding of multiple reward-related factors in transient and sustained high-frequency activity in human OFC. Ignacio Saez, Jack Lin, Arjen Stolk, Edward F. Chang, Josef Parvizi, Gerwin Schalk, Robert T. Knight and Ming Hsu. Current Biology, Sep 2018.

Sub-second dopamine fluctuations in human striatum encode superposed error signals about actual and counterfactual reward. Kenneth T. Kishida, Ignacio Saez, Terry Lohrenz, Mark R. Witcher, Adrian W. Laxton, Stephen B. Tatter, Jason P. White, Thomas L. Ellis, Paul E. M. Phillips, P. Read Montague. Proceedings of the National Academy of Sciences, Jan 2016.

Dopamine Modulates Egalitarian Behavior In Humans. Ignacio Saez, Lusha Zhu, Eric Set, Andrew Kayser and Ming Hsu. Current Biology, Mar 2015.

Contact Us

If you are a patient interested in participating in one of our research studies, or a researcher interested in collaborating in some of our projects, please contact the lab directly at hs-saezlab@ucdavis.edu.

Join the Lab

Multiple part-time and full-time positions are available for researchers of different career stages (undergrad to postdoctoral). For more details, please visit the lab page or email directly to hs-saezlab@ucdavis.edu.

Postdoctoral Fellows: 

A funded position is available to work on invasive electrophysiology approaches to the study of human decision-making. 

Graduate Students: 

The lab is open for research rotations for students admitted in the UC Davis Neuroscience Graduate Program. 

Undergraduate students:

Undergraduate students interested in carrying out research in the lab with backgrounds in neuroscience, psychology, biomedical engineering, computer science and statistics are encouraged to apply for research internships. Research projects can be designed to accommodate your skills and interests within the lab, and will provide academic credit.