Visiting Assistant Professor
Anatomy and Neurobiology
20 Penn Street, HSF, Room 280E
Education and Training
- PhD - Pharmacology, Chinese Academy of Medical Sciences and Peking Union Medical College
- Postdoctoral Associate - Neuroscience, Yale University
- Research Associate - Neuroscience, Case Western Reserve University
Sensory physiology, synaptic plasticity, neural circuits, neuronal excitability, neuromodulation, learning and memory, neurodegeneration, olfactory neurobiology, visual neurophysiology, neuropharmacology
- Liu, S., Puche, A.C., Shipley, M.T. (2016) The Interglomerular Circuit Potently Inhibits Olfactory Bulb Output Neurons by Both Direct and Indirect Pathways. Journal of Neuroscience, 36(37):9604-17.
- Cockerham, R., Liu, S., Cachope, R., Kiyokage, E., Cheer, J.F., Shipley, M.T,, Puche, A.C. (2016) Subsecond Regulation of Synaptically Released Dopamine by COMT in the Olfactory Bulb. Journal of Neuroscience, 36(29):7779-85.
- Chu, S., Liu, S., Duan, W., Cheng, Y., Jiang, X., Zhu, C., Tang, K., Wang, R., Xu, L., Wang, X., Yu, X., Wu, K., Wang, Y., Wang, M., Huang, H., Zhang, J. (2016) The anti-dementia drug candidate, (-)-clausenamide, improves memory impairment through its multi-target effect. Pharmacology & Therapeutics, 162:179-87.
- Liu, S., Shao, Z., Puche, A. C., Wachowiak, M., Rothermel, M. and Shipley, M. T. (2015) Muscarinic receptors modulate dendrodendritic inhibitory synapses to sculpt glomerular output. Journal of Neuroscience, 35 (14): 5680-92.
- Liu, S., Plachez, C., Shao, Z., Puche, A. C. and Shipley, M. T. (2013) Olfactory bulb short axon cell release of GABA and dopamine produces a temporally biphasic inhibition-excitation response in external tufted cells. Journal of Neuroscience. 33 (7): 2916-2926.
- Shao Z, Puche A, C., Liu S, & Shipley MT (2012) Intraglomerular inhibition shapes the strength and temporal structure of glomerular output. J Neurophysiol 108:782-793.
- Liu S, Aungst JL, Puche AC, & Shipley MT (2012) Serotonin modulates the population activity profile of olfactory bulb external tufted cells. J Neurophysiol 107:473-483.
- Liu S & Shipley MT (2008) Multiple conductances cooperatively regulate spontaneous bursting in mouse olfactory bulb external tufted cells. J Neurosci 28:1625-1639.
- Liu S & Shipley MT (2008) Intrinsic conductances actively shape excitatory and inhibitory postsynaptic responses in olfactory bulb external tufted cells. J Neurosci 28:10311-10322.
- Liu S & Friel DD (2008) Impact of the leaner P/Q-type Ca2+ channel mutation on excitatory synaptic transmission in cerebellar Purkinje cells. J Physiol 586:4501-4515.
- Xu L, Wang XY, Liu S, & Zhang JT (2007) Two forms of long-term potentiation induced by different compounds. J Asian Nat Prod Res 9:217-222.
- Xu L, Liu S*, & Zhang JT (2005) (-)-Clausenamide potentiates synaptic transmission in the dentate gyrus of rats. Chirality 17:239-244. *(co-first author)
- Liu S, Rao Y, & Daw N (2003) Roles of protein kinase A and protein kinase G in synaptic plasticity in the visual cortex. Cereb Cortex 13:864-869.
I have broad interest in the neuroscience with particular emphasis on cellular, synaptic and circuit mechanisms underlying sensory perception, motor control, learning and memory in both normal and pathological conditions. My current research focuses on how local circuits encode and transform sensory information in the olfactory system, an evolutionarily conservative sensory modality. My research uses the olfactory bulb (OB) as a model system as its major anatomical pathways from peripheral sensory neurons, second-order output neurons, to downstream cortical neurons are straightforward and relatively clear.
Functional Mechanisms Underlying the Intrabulbar Associational Circuit
The olfactory system is not only anatomically conservative among animal species but also functionally powerful in a sense of detecting and differentiating millions of odorant molecules existing in the environment and sometimes at extremely low concentration. This powerful sensation could be due to the diverse superfamily of odor receptors (ORs) expressing in the olfactory sensory neurons (OSNs) and unique downstream neural circuits processing odor information. There are ~1200 functional ORs in rodents and ~400 in human. Each OSN expresses only one type of ORs. Interestingly, axons of OSNs expressing a given type of ORs project and converge onto one pair of spherical structures termed "mirror glomeruli" located on the medial and lateral side of each OB even though the corresponding OSN cell bodies are randomly distributed in the olfactory epithelium. The physiological significance of this organizational arrangement remains unclear. However, it has been known for decades that mirror glomeruli are anatomically interconnected by the intrabulbar associational circuit (IAC) derived from a subpopulation of OB neurons, which exclusively express the neuropeptide cholecystokinin (CCK). With CCK as a molecular biomarker to isolate the IAC, we will integrate optogenetics, chemogenetics, in vitro and in vivo electrophysiology, and behavioral approaches in this project to reveal the functional mechanisms underlying this CCKergic IAC at cellular, network and behavioral levels. The expected outcome will not only advance our understanding how olfactory circuits process odor information in the OB before being transmitted to downstream centers but also shed important light on the physiological function of mirror glomeruli organization.
1R01DC014447-01A1 Liu (PI)
02/09/2016 - 01/31/2021
The overall goal of this project is to understand the functional operation of a fundamental and unique circuit linking the glomeruli receiving olfactory sensory neurons expressing the same odorant receptor in the olfactory bulb with multidisciplinary approaches at cellular, network and behavioral levels.
Total cost: $261,800/yr.
We use a broad range experimental techniques in the laboratory.
In vitro: patch clamping recording in brain slices to measure synaptic transmission, neuronal excitability, ionic channel activity in cell type-specific neurons from gene-targeted GFP mice.
In vivo: single-unit and field potential recording in anesthetized and awake freely-moving animals. Whole cell patch clamp recording of synaptic and spiking activity from interested neurons in anesthetized rodents.
Opto- and chemogenetics
Optogenetics and chemogenetics are integrated with electrophysiology and behavioral approaches to characterize the anatomical and functional mechanisms underlying cell-type specific neural pathways and circuits.
Behavioral tasks including Buried Food Test and Two-bottle Odor Discrimination are used for measure animal’s ability and sensitivity of detecting odors.
Neuronal Anatomy and Histochemistry
Reconstructions of physiologically-characterized, biocytin or dye-filled neurons; anterograde or retrograde tract tracing, immunohistochemistry
Xicui Sun, PhD - Postdoctoral Fellow