《Neuron》：首次发现大脑视觉中心兴奋波的模式

神经学家长期以来相信大脑视觉处理方式是通过神经元构成的通路，就好像通过电线从一处传到另一处的电话信号。但最近来自Georgetown大学医学中心的科学家发现，视觉信息还通过另一种方式处理，类似于在大脑区域间来回振荡。这一结果发表在《Neuron》上。 

生理学和生物物理学副教授Jian-young Wu是文章通讯作者，早年毕业于北京大学。

Jian-young Wu表示：“我们发现信号在大脑中类似波，来回传播。”这对于长期以来持有的大脑处理感官信息的方式是一个挑战，Wu说：“一个传统模型认为神经元结合在一起构成特殊通路。但是新的成像技术告诉我们并非完全如此。”

小组使用电压灵敏染料成像技术对脑皮层类似波的模式进行了成像。他们用特殊染料结合到神经元细胞膜上，它们会随着电压穿过神经元而改变颜色。而传统上，科学家通过电极来测量大脑的活动。

Wu相信这一模式对于触发和组织包含了大量神经元的大脑活动很重要。寻找在视觉处理过程中的波是迈向理解大脑如何处理感官信息的重要一步。这一过程能帮助科学家了解帕金森氏症和癫痫症患者脑部产生的异常波，以及痴呆症患者为何无法正确组织神经元的活动。 

Wu认为还需要进行进一步的研究来理解人类大脑中正常和异常的波。他表示：“了解大脑如何处理这些波能帮助我们了解宇宙中最复杂体系之一——大脑的功能。”

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¡¯s 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