Research intersts

Visual perception has held a special point of fascination with philosophers and scientists for thousands of years. What appears to us an effortless task, the opening of our eyes, engages an extensive and anatomically complex network of brain areas. It is these brain areas which afford us, as Aristotle phrases, the delight and exploratory power of seeing. Neuroscientists are slowly unraveling this complexity with an eye to both pure knowledge of our dominant sense, and also its gateway status to cognition and disease. A central question in vision is how the cortex integrates local visual cues to form global representations, which mustinvolve an interactive process that occurs at multiple brain areas at the same time.Our laboratoryresearch interest is to study cortical mechanisms underlying the integration from local into global, with special focus on neural mechanisms and circuits responsible todifferent visual perceptual phenomena.Our lab brings together a range of multi-disciplinary techniques, including in vivodual optical imaging,in vivo simultaneous multi-single unit recording of different cortical areasalong with advanced optogenetic approaches. Both anesthetized and awake animal preparations are carried out in our Lab.

Cortical mechanisms of local⬄global orientation/contour representations:(1) A central question in vision is how the cortex integrates local cues to form global representations along the visual hierarchy. Orientation and contour are fundamental visual features of objects. We investigate cortical mechanisms of global orientation and contour representations in V1, V2, and V4 of the macaque ventral visual stream,particularly at the situation when the local and global visual features are different. (2) Spatial vision is critical for primates to see effortlessly.One paradox in the primate ventral stream concerns the increasing complexity of encoded features while spatial frequency (SF) selectivity decreases drastically along the hierarchy. This raises a fundamental question: how is high and low spatial frequency information combined for spatial vision along the visual hierarchy? In other words, we investigate the spatial analysis along the visual hierarchy for detailed object representation. The research outcome will enlighten how high-tier cortices integrate local spatial features to form global representations.

The cortical mechanisms of motion perception in the primates:Visual movements are processed primarily by a magnocellular dominated stream (though there is an increasing appreciation of a contribution by the parvocellular system) through the lateral geniculate (LGN), visual cortices V1/V2, and on into MT and MST. How this integration and segregation of motion signals takes place is still only partially understood. We specifically ask how macaque MT/MST integrates both direction and motion-axis signals at different motion speeds and what the integrative neural mechanisms underlying illusory motion in V1, MT, and MST of the macaque are.These studies will help us to better understanding the fundamentals of motion integration from local into global and the neural mechanism underlying the encoding ofvelocity invariantlyacross moving objects.

To investigate the neural mechanisms of visual illusion and perceptual filling-in: Visual illusions, particularly filling-in dramatically reveals the dissociation between the retinal input and the percept, and raises fundamental questions about how these two relate to each other. Illusion and filling-in occurs both in normal and pathological vision, and their spatiotemporal characteristics suggest interactions among multiple levels of visual system. Details of these neural interactions between lower and higher visual areas are the important questions to be studied.

The functionalrole of extensive cortical feedback and the predictive coding:One of the most interesting challenges in vision is to unravel the precise functional roles of massive cortical feedback that parallel the ascending feed-forward pathways. The role of cortical layer 6feedback cells in visual processing is of particular appeal, for Layer 6 cells in the visual cortex sitting in a crucial place in the circuitry involve in the early processing of the visual input in higher mammals such as cats and primates. Our interests lie in understanding how these cells may gate and modulate the information flow through the visual hierarchy.Because neural feedback is increasingly understood within influential Bayesian theories of brain function, dissecting the causal influence of cortical feedback will provide highly instructive for core hypotheses of the cellular foundations of cognition.

From bench work to the bedside – the restoration of vision:“What is sight restoration? Certainly meaningless blobs of light should not be considered as such, but equally the ability to restore even relatively poor vision would be a triumph (Fine et al., 2015)”. By using optogenetic retinal or cortical prosthesis, we investigate how to generate orientation/direction-selective responses in V1 of blind subjects, a crucial step towards the restoration of the early vision for form and motion perception. 

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Feb/1995-Aug/1998     University of Science and Technology of China      Ph.D

   

Jul. 2016~now,             Shanghai Institutes for Biological Sciences, CAS,   senior Investigator

Sept.2007 – Jun.2016,     Shanghai Institutes for Biological Sciences, CAS,   Investigator

June 2006 – May 2009      The Wellcome Trust Career Development Fellowship (Independent). Faculty   of  Life Science, the University of Manchester, UK

Jul. 2005 – May. 2006     Senior Research Fellow (Senior Postdoc), Faculty of Life Science, The University of Manchester, UK. 

Jul. 2004 – Jul. 2005     Senior Research Fellow (Senior Postdoc), Dept of Optometry & Neuroscience, The University of Manchester Institute of Science & Technology (UMIST), UK.

Nov. 1998 – Jun 2004       Research Fellow (Postdoc), Professor Adam Sillito’s laboratory, Department of Visual Science, Institute Of Ophthalmology, UCL, London

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Advanced Neurobiology

（1） Representation of illusory and physical rotations in human MST: A cortical site for the pinna illusion., Hum. Brain Mapp. 2016, corresponding author

（2） Breaking cover: neural responses to slow and fast camouflage-breaking motion., Proc. R. Soc. B, 2015, corresponding author
（3） The mechanism for processing random-dot motion at various speeds in early visual cortices., PLoS One, 2014, corresponding author
（4） Asymmetrical color filling-in from the nasal to the temporal side of the blind spot., Front. Hum. Neurosci., 2014, corresponding author
（5） Orientation-cue invariant population responses to contrast-modulated and phase-reversed contour stimuli in macaque V1 and V2., PLoS One, 2014, corresponding author
（6） Equivalent representation of real and illusory contours in macaque V4., Journal of Neuroscience., 2012, corresponding author
（7） Distinct functional organizations for processing different motion signals in V1, V2, and V4 of macaque., Journal of Neuroscience., 2012, corresponding author

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已指导学生

yanxia Pan  01  19179  

jiapeng Yin  01  19179  

现指导学生

hui Li  01  19179  

zheyuan Chen  01  19179  

hongliang Gong  01  19179  

junxiang Luo  01  19179  

ye Liu  01  19179  

xu LIU 01  19179