Krasnow Institute > Monday Seminars > Abstracts

Jian-young Wu
Department of Neuroscience
Georgetown University
Washington, DC

I will start with how voltage-sensitive dye (VSD) imaging works and then show cortical wave dynamics in rat brain slices and in vivo. Propagating waves (a.k.a. "traveling waves") of neuronal activity occur during sensory evoked event and spontaneous oscillations in many structures in the central nervous systems. In sensory events propagating waves bring spatial coherence to the cortical neurons.  Most of the cortical neurons are depolarized by the wave instead of direct thalamic afferent input. I will also discuss spatial-temporal patterns of the propagating waves in rat neocortex. Oscillations in the cortex manifested into a patterns of "one-wave one-cycle", i.e., each oscillation cycle associates with an excitation wave propagating across the tissue. Along the propagating path a spatial phase gradient was organized, depend on the propagating velocity. The propagating direction and velocity of the waves varied from cycle to cycle, suggesting complex and dynamic interactions among local oscillators.  Special patterns such as spirals emerge when multiple waves interact in brain slices as well as in cortex in vivo. I will also present a computer simulation of spiral patterns in a 2-D network of Wilson-Cowan equations, demonstrating that oscillations can be generated in the cortical neurons from wave patterns without cellular pacemakers. In conclusion, propagating waves may determine when and where excitation may occur and the patterns of neurons that are bind together to active. VSD imaging is a unique tool for study wave patterns on the meso-scale of 100 um x 10 ms.  
Support Contributed By: NIH grants R-01NS36447, R-01NS 59034

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