《Neuron》：首次發現大腦視覺中心興奮波的模式

神經學家長期以來相信大腦視覺處理方式是通過神經元構成的通路，就好像通過電線從一處傳到另一處的電話信號。但最近來自Georgetown大學醫學中心的科學家發現，視覺信息還通過另一種方式處理，類似于在大腦區域間來回振蕩。這一結果發表在《Neuron》上。 

生理學和生物物理學副教授Jian-young Wu是文章通訊作者，早年畢業于北京大學。

Jian-young Wu表示：“我們發現信號在大腦中類似波，來回傳播。”這對于長期以來持有的大腦處理感官信息的方式是一個挑戰，Wu說：“一個傳統模型認為神經元結合在一起構成特殊通路。但是新的成像技術告訴我們并非完全如此。”

小組使用電壓靈敏染料成像技術對腦皮層類似波的模式進行了成像。他們用特殊染料結合到神經元細胞膜上，它們會隨著電壓穿過神經元而改變顏色。而傳統上，科學家通過電極來測量大腦的活動。

Wu相信這一模式對于觸發和組織包含了大量神經元的大腦活動很重要。尋找在視覺處理過程中的波是邁向理解大腦如何處理感官信息的重要一步。這一過程能幫助科學家了解帕金森氏癥和癲癇癥患者腦部產生的異常波，以及癡呆癥患者為何無法正確組織神經元的活動。 

Wu認為還需要進行進一步的研究來理解人類大腦中正常和異常的波。他表示：“了解大腦如何處理這些波能幫助我們了解宇宙中最復雜體系之一——大腦的功能。”

附：

Jian-young Wu, Ph.D.
Professor of Physiology and Biophysics
Ph.D., Peking University, China, 1986

Research

My laboratory studies the spatiotemporal patterns of neuronal activities in the mammalian neocortex. Large scale neuronal activity is a hallmark of living brain. All cortical functions are carried out by organized activation of large number of neurons. Studying the spatiotemporal patterns of neuronal population activity may provide help in the understanding of normal brain functions such as sensory and motor processing and in pathological disorders such as epilepsy and Parkinson?ˉs disease.

My general hypothesis is that propagating waves are a basic pattern of population neuronal activity in the neocortex. We use voltage-sensitive dyes and optical imaging techniques to visualize these waves. In the past few years, we have documented a variety of waveforms (e.g., plane wave and spirals) in brain slices during artificially induced oscillations. Using neocortical slices and mathematic models we are studying the initiation of the waves and the factors that control of the propagating direction and velocity.

We are also involved in the development of optical imaging techniques. Imaging propagating waves in intact brain is technically difficult. Other imaging methods (fMRI, PET or MEG) provide inadequate spatiotemporal resolution. We are improving the optical imaging techniques with a hope to visualize the waves in the cortex in vivo during sensory processes and in awake animals while behavioral and cognitive tasks are performed.

Selected Publications:

Wu, J.-Y., J.A. London, D. Zecevic, L.B. Cohen, H.-P. Hoepp and C. Xiao. Optical monitoring of neuron activity during the Aplysia gill-withdrawal reflex. Experientia. 44(5), 369 - 375,1988
Cohen, L.B. and J.-Y. Wu. One neuron, many units? Nature, 346, 108-109,1990
Wu, J.-Y., C.X. Falk, and L.B. Cohen. Neuronal activity during different behaviors in Aplysia: A Distributed Organization? Science, 263:820-823,1994
Wu, J.-Y., Y. Tsau, H.P. Hoepp, L.B. Cohen, A.C. Tang and C.X. Falk. Consistency in Nervous system: Trial-to-trial and animal-to-animal variations in the response to repeated application of a sensory stimulus in Aplysia. J. Neuroscience, 14(3):1366-1384,1994
Tsau, Y., L. Guan, and J.-Y. Wu. Initiation of Spontaneous Epileptiform Activity in the Neocortical Slice. J.Neurophysiology,80: 978-982,1998 .pdf
J.-Y. Wu,L. Guan, and Y. Tsau. Propagating activation during oscillations and evoked responses in neocortical slices. J. Neuroscience,19: 5005-5015,1999 .pdf
J.-Y. Wu, L. Guan, L. Bai and Q. Yang. An evoked all-or-none population activity in rat sensory cortical slices. J. Neurophysiology, 86:2461-2474,2001 .pdf
Jin, W-j., R-j Zhang and J.-Y. Wu. Voltage-sensitive dye imaging of population neuronal activity in cortical tissue. J. Neuroscience Method, 115 13-27,2002 .pdf
Bao, W. and J.-Y. Wu. Propagating wave and irregular dynamics: Spatiotemporal patterns of cholinergic theta oscillations in neocortex, in vitro J. Neurophysiology,90:333-41,2003 .pdf