Education

2005      Ph.D.           University of Minnesota, USA (Biomedical Engineering)
2000      B.Eng.         Zhejiang University, China (Biomedical Engineering)

Academic appointments

2009~present        Assistant Professor        University of Massachusetts
2008~2009            Research Assistant Professor      University of Minnesota
2006~2008            Research Associate         University of Minnesota
2005~2006            Postdoctoral Associate    University of Minnesota

Functional Magnetic Resonance Imaging

Functional Magnetic Resonance Imaging (fMRI) is a technique that can noninvasively map brain activation with a very high spatial resolution and a large field of view. This technique, which has been widely used for investigating various brain functions, is based on locally coupled neuronal activity and hemodynamic changes (also called neurovascular coupling). At activated brain regions, cerebral blood flow increases overcompensate oxygen consumption rate increases in response to a higher demand of energy, resulting in a local oxygenation level change which can be detected in MR images.  Therefore, the signal source of fMRI is termed the blood-oxygenation-level dependent (BOLD) signal.

The research in our lab encompasses both the mechanism of fMRI and fMRI applications. Specifically, our research is designed to quantitatively bridge the gap between the BOLD signal and the underlying neuronal activity by using simultaneous multi-modal (EEG and fMRI) acquisition. We also study the mechanism and spatiotemporal characteristics of the BOLD signal. We have the ability of obtaining high-resolution fMRI on a submillimeter scale so that we can map elementary functional structures (e.g. columns) in the brain. By designing novel paradigms, we are developing approaches to extract fast temporal information (in tens to hundreds of milliseconds) of neural interaction using the slow BOLD signal.

Resting State and psychiatric disorders

Normal brain consists of numerous neural networks coordinately working together. For the brain to function properly, the activities of these neural networks need to harmonize sequentially or concurrently while electrophysiological signals propagate along different neuronal groups. As a result, investigating the functions of neural networks and their relationships plays a fundamental role in neuroscience. This task is conventionally explored with studies of the brain responses to carefully controlled sensory, cognitive and motor events. Nevertheless, a series of recent studies demonstrate patterned activities exist within various brain networks during resting and passive task states. Distributed brain regions spontaneously increase and decrease their activity together within functional-anatomic networks, even under anesthesia. These studies led to a hypothesis that the human brain is intrinsically organized into dynamic, anti-correlated functional networks.

In our lab, we use fMRI to investigate resting state functional connectivity in several animal models. Our research is designed to examine whether connectivity among various brain regions will change in different psychiatric disease models.

When the brain is activated, local neuronal activity will induce electromagnetic field changes which can be detected by evoked potentials. At the same time, through a mechanism called neurovascular coupling, local neuronal activation is always spatially accompanied with vascular and metabolic changes. These vascular and metabolic changes will create changes in oxygenation level at activated brain regions.  Interestingly, MR signal is sensitive to these oxygenation level changes (referred to as the BOLD contrast). As a result, brain activation can be non-invasively mapped using MRI.