Picower Institute of Learning and Memory
Massachusetts Institute of Technology
46-6227, MIT, Cambridge, MA, 02139
Email: hbyu@mit.edu
Oct. 2000 – Postdoctoral fellow, Prof. Mriganka Sur’s lab, Picower Institute of
Learning and Memory, MIT, USA
Oct. 1997 – Sept. 2000 PhD, Prof. Tiande Shou’s lab, School of Life Science, Fudan University, Shanghai, China
Sept. 1997 – Sept. 1995 PhD, Prof. Tiande Shou’s lab, Department of Biology, University of Science and Technology of China (USTC), Hefei, China
July 1995 – Sept. 1991 BA, Department of Biology, USTC, Hefei, China
Honors, Achievements and Membership
1991 No. 1 in Xingjiang Providence in National College Entrance Test 1991 Zhang Zongzhi Scholarship, USTC 1995 Baogang National Scholarship for college students 1996 Huawei Scholarship, USTC 1999 Shanghai—Unilever Research Scholarship 1999 Zhenghua Scholarship, USTC 2000-present Membership, Society for Neuroscience 2007-present Editor, Frontiers in Neuroscience
Work being cited and reviewed
One of my major work, “The coordinated mapping of visual space and response features in visual cortex.”( Neuron 47:467-280, 2005) was reviewed by Prof. A. Das in the same issue of Neuron (“Cortical maps: Where theory meets experiments.” Neuron 47:168-171, 2005), and was evaluated as “elegantly combined computational algorithms with physiological measurements to closely examine and, largely, validate the models of cortical organization.”, even though our major findings oppose his previous work (A. Das, C.D. Gilbert, Nature, 387:594-598, 1997).
Research Background
- In the first two years as a graduate student, I examined the binocularity of relay cells in lateral geniculate nucleus by incompletely sealed whole cell patch recordings in vivo, and found that 90% of the relay cells received binocular inputs. It modifies the long-term viewpoint that LGN cells only receive inputs from monocular eye and have no binocular competition (Brain Research, 2003).
- In 1997-2000, as a senior graduate student, I moved to Fudan University following Prof. Tiande Shou, helping him establish the Vision Research Lab from the very beginning. Working closely with Mr. Kun Zhang, a talented graduate student in Fudan (now a faculty in University of California, San Diego), we established the first intrinsic signal optical imaging system in China. Combined with our home-made local drug application system, I studied the excitatory and inhibitory mechanisms of orientation maps in the primary visual cortex of cats. It reveals that inhibition is not necessary in the formation of orientation maps, but is essential in keeping the appropriate excitation-inhibition balance so that the orientation selectivity can be sharpened through “iceberg effect”. Besides the numerous detailed studies in the mechanism of orientation selectivity in the past several decades, this is the first global evaluation of all the neurons in the whole visual cortex, and our findings oppose the cross-inhibition model and are in favour of the recurrent model at the population level (Neuroimage, 2008).
- In 2000-2003, I modified the hardware, software and data analysis of the commercial optical imaging system (Imager 2001, Optical Imaging Inc.) in Prof. Mriganka Sur’s lab in MIT, introduced the fast optical imaging technique so that the functional imaging time (2-3 hours for one feature map with reasonable quality) could be shortened by 4-6 times. It enabled my research in the relationship between multiple feature maps (including visual space, orientation, direction, ocular dominance, spatial frequency) in the primary visual cortex of ferrets. We found that different feature maps interacted with each other, by following one general rule that high gradient regions of maps avoided each other, so that a uniform coverage of all the features’ combination could be achieved. We further examined this idea in a self-organized model, in collaboration with Dr. Dezhe Jin (now a faculty in University of Pennsylvania), and revealed incredible consistency between the model and experiments (Neuron, 2005). This work was commented in the same issue of Neuron, and was cited over 20 times so far, including a review in Science (310:805-810, 2005).
- In 2003-2005, inspired by the comment of PILM head, Nobel Prize winner, Prof. Susumu Tonegawa, “The two photon microscopy is a revolutionary technique that will transform the neuroscience field, and it is comparable to the Nobel Price winning technique of patch clamp.” I chose to stay in MIT, and established in vivo chronic two photon imaging system in high mammals, together with Dr. Ania Majewska (now a faculty in University of Rochester). We monitored the morphology of the same dendritic spine in vivo before and after short term monocular deprivation, as well as after short term binocular recovery, through a transparent window implanted above the visual cortex, which also enabled combined chronic optical imaging. We found that dendritic spines disappeared during 3 hours’ monocular deprivation and reappeared after the following 3 hours’ recovery, consistent with the rapid functional shift of ocular dominance map simultaneously measured by optical imaging. It is a strong experimental confirmation of the century long hypothesis that dendritic spine can be the structural basis of rapid functional plasticity. (Nature, in preparation).
- From 2005, I extended our two photon system from structural imaging to the field of functional monitoring in vivo, with the initial help of Dr. Brandon Farley, and then together with Dr. James Schummers. We labelled hundreds of cells within 300 microns of the visual cortex in vivo by calcium fluorescent dye, and simultaneously measured their response properties by giving all kinds of visual stimuli. Using this technique, for the first time in the field, we obtained precise mapping of multiple feature maps at the single cell resolution, and investigated their highly localized relationship, guided by the viewpoint in our Neuron paper. We found a unanimously close match between the model and experiments, and importantly, we clarified and explained the origin of sharp conflicts between three different groups of results, which were measured by less precise optical imaging experiments or single unit recordings with poor spatial information in the past ten years (Nature, in preparation).
