Since January 1, 2011, I have joined Dr. Jonathan D. Victor's lab at Department of Neurology and Neuroscience, Weill Medical College of Cornell University.
If you are interested in my work at Mount Sinai School of Medicine, Please stay on...
Who am I?
Neuroscientist -- a combination of Experimental and Computational aproaches to tackle systems neuroscience questions.
What I do?
Plainly and braodly speaking, three things: 1). Collecting massive data from experiments on brain; 2) statistically and computationally extract the neural information from the experimental data; 3) translate the findings to clinical treatment to improve human health.
What is my research about?
My research interests focus on neural computation in brain neural circuits at system level, namely, how the brain circuitry integrates and processes sensory information to form the perceptions of the external worlds, make decisions, and execute movements. My current and previous studies fall into three subareas of systems neuroscience: neural computation in visual pathways, sensory integration in neural circuits for cardiorespiratory regulation, and learning and memory.
Current Research
Neurons in brain circuits interact with each other, and the interactions result in output signals which, on one hand, faithfully convey the initial sensory input information, on the other hand, (inevitably) contains neural information with novel properties. In addition, the neural processing in the neural circuits often receives feedback and is perturbed by many factors that, in various degrees change, the outcomes of the computation through affecting the performance of the robustness of the neural calculus in the neural circuits. A central question in brain research is to understand the process of neural computation in neural circuits. To answer this question, we need to address: 1). How is the neural sensory information coded in the neural circuits, and how do neuronal interactions affect neural information coding efficiency in terms of a specific physiological function? 2). Do neurons in neural circuits convey the information with redundancy? 3). Do neurons act together in a synergistic manner or just simply by producing a linear summation function? 4). How does neural feedback modulate the neural processes in the neural circuits?
To examine these fundamental questions experimentally, I took the visual system as a convenient model (due to its well-established quantitative stimulus-response models) to collect and measure the information of a large neuronal population in a controlled manner. Briefly, I collect extracellular neuron activities from hundreds of neuron using multielectrode recordings from both the LGNs and visual cortex of nonhuman primates which were given various visual stimuli (such as, full field stimuli with pseudorandom luminance sequences derived from natural scenes, drifting gratings with various contrasting spatial and temporal frequencies, or in constant light or in darkness). After recording simultaneously from a population of LGN neurons under control conditions, the visual cortex was then inactivated in the visual cortex and the measurements were repeated.
From this study, We have developed several main findings: 1). Sensory integration and fidelity of signal transmission in the visual pathways. 2). At neural population level, the neural information shows significant redundancy and synergy; 3). The feedback modulates the dynamics of information transmission; 4). The cortical feedback significantly improves precision of our vision through regulating functional connectivity of LGN local neural microcircuits; 5) The cortical feedback markedly changes the information transmission rates at neural population level.
My Previous Researches:
Neural Circuits of Respiratory Motor Control
There are three main categories of neurons in our brain according to their functions: sensory neurons, interneuron and motor neurons. It is estimated that over 95% of entire brain neural computation is conducted within the interneurons which are hierarchically organized as functionally specific neural circuits and, in turn, form neural pathways in the brain. The complexity of human behavior depends less on the specialization of individual nerve cells, but more on these cells form precise anatomical circuits. Therefore, it is of great importance to study how neural circuits organize and behave. My studies at HST of MIT were precisely targeted at this critical question. I pinpointed how pontine neural circuits facilitate respiratory phase-switching, and discovered the pontine neural local circuits of respiratory phase-switching, namely, the transition from inspiration phase to expiratory phase. The study provided direct evidence for how constant inspiration can be transformed to inspiratory-expiratory oscillation process.
Pontine local neural ciruits integrate multiple sensory input and associated to respiratory neural control.
For more information about the study please see my presentation in the sfn annual meeting (The Talk at 37th Annual Meeting of Society for Neuroscience: 2006)
Sensory Integration of Pressure-sensitive Neurons Cardiorespiratory Neural Pathway
Nerve cells are able to convey unique information because they form specific networks. In the neural network, the sensory information goes through series of neural computations and finally reaches the motor neurons. Although there are a host of studies on how specific sensory information is integrated in primary relay nuclei, few studies to address this neural process at neural population level, this is particular the case in cardiovascular regulation.
My doctoral thesis was focusing on how pressure-sensitive neurons in the brain integrated into the neural pathway for cardiovascular regulation. The study discovered the pressure-sensitive neurons in paratrigeminal nucleus, a medullary structure that integrates and relays sensory information containing cardiorespiratory, nociceptive sensory inputs into the brain and participate cardiovascular regulation. This significant finding was the key for understanding how our brain can control and maintain normal blood pressure and adjust it according the metabolic demands of our body. This was the first physiological evidence showing existence of pressure-sensitive neurons in the paratrigeminal nucleus. Based on this study, the paratrigeminal nucleus has been recognized as an important blood pressure sensory relay station in the central neural pathway of cardiovascular control in the brain (Yu and Lindsey, 2003, Baroreceptor-sensitive neurons in the rat paratrigeminal nucleus). For this study I pioneered the multiple-site, multiple-electrode technology for studying neural control of cardiovascular system in an unconstrained, freely behaving animal. Based on this study and the novel experimental paradigm, a series of key scientific findings have been established in the research group.
In summary, my current and previous research has been mainly focusing on sensory integration, neural computation in neural circuit, the feedback and neural information processing. In all these studies, I mainly emply multiple-channel neuronal recording technique for acquiring neural information in large-scale neural population in neural pathways both in freely behaving animal model and acute anesthetized animal model.