[Brainmap]: Ed X. Wu, PhD - Optogenetic fMRI Dissection of Long-Range Brain Networks

Abstract

fMRI provides a versatile imaging platform for mapping brain activities in vivo. More recently, resting-state fMRI (rsfMRI) has emerged as a powerful tool for mapping long-range brain networks. However, both methods only reflect the gross outcome of the complex and cascaded activities of various cell types and networks, posing limitations when dissecting brain networks and their functions. Optogenetics techniques provide spatiotemporally precise modulation of genetically defined neuronal populations in vivo. Here we combine fMRI with optogenetic perturbations and electrophysiology to capture and analyze whole brain activity and long-range circuits. We apply this capability to interrogate the spatiotemporal response properties of two distinct long-range networks, namely, thalamo-cortical and hippocampal-cortical networks. We examine the functional effects of low-frequency optogenetic stimulation within these two networks on brain responses to external sensory stimuli, on functional connectivity at resting-state, and on cognitive behaviors.  Our findings reveal that low frequency activity governs large-scale, brain-wide connectivity and interactions to coordinate the functional integration of remote brain regions. Further, low-frequency hippocampal-cortical activity drives rsfMRI connectivity. These findings advance our present understanding of the neural basis of long-range functional connectivity as measured by rsfMRI. 

About the Speaker

Dr. Wu is the Lam Woo Professor and Chair of Biomedical Engineering at the University of Hong Kong (HKU). From 1990 to 2003, Dr. Wu worked in Columbia University on the 3D PET and high-field MRI system engineering, first as an Assistant Professor and later as an Associate Professor of Radiology and Biomedical Engineering. Dr. Wu joined HKU in 2003. His present research focus is to develop MRI methodologies for functional and microstructural characterization of biological systems, particularly CNS, using rodent models. Dr. Wu is an elected Fellow of ISMRM and IEEE. He is the Asia Pacific Editor of NMR in Biomedicine since 2011.