[Seminar]"Propagating waves in brain cortex: Cloud computing?" by Prof. Jian-young Wu

Speaker: Professor Jian-young Wu

Title: Propagating waves in brain cortex: Cloud computing?

Abstract:

      Brain functions are carried out by the collective activity of millions to billions of neurons. We use voltage-sensitive dyes to visualize the activity of cortical neurons and to study how a large number of neurons interact. Spatiotemporally, the activity of the neurons is organized in the cortex as propagating waves.

      Excitatory and oscillatory waves are two common types of waves seen in the cortex. Excitatory waves are composed of an excitation front, a body of excitation followed by a band of non-active refractory periods. Oscillatory waves are composed of coupled oscillators, which gives rise to a variety of waveforms: propagation velocity and direction.

       In my lecture, I will first introduce the methods for imaging the cortex with voltage-sensitive dyes and then show a few common patterns of propagating waves seen in the cortex.

Biography:

I am an expert in system neuroscience and I have been a Professor in neuroscience at Georgetown University Medical Center since 2002. My main research interest is population neuronal activity in the nervous system. Population activity evolves large number of neurons forming parallel routes. Starting from my postdoctoral training, I am interested in a distributed network organization [4]. “Distributed organization” means that multiple functions are generated by different configurations of a shared large neuronal population. This is different from the concept of dedicated circuit for each function. One of my current projects is the sharp wave-ripple (SPW-R) in hippocampus. SPW-Rs are important population events for consolidation of hippocampus dependent memory. About 15% of the neurons (~100,000) are activated during each SPW-R event, raising the probability that the memory traces are stored and replayed in a distributed way, that each memory element is represented by small modifications on a large number of synapses. While I am relatively new in the SWR field, I have two recent publications in SWRs in brain slices [1-2]. The proposed project will move my research from slices to in vivo. I have more than 20 years of research experience in voltage-sensitive dye imaging, studying spatiotemporal patterns of neuronal activities, particularly the propagating waves, in the mammalian neocortex [3-4]. We combine biological experiment and mathematic models to study the mechanisms for initiating waves and the factors that control the propagating direction and speed. I am also involved in the development of optical imaging techniques that can recognize small fractional signals under a high background light intensity. I enjoy doing experiments myself, being immersed in data analysis, and spending time solving technical challenges in experiments. I see myself not only as a principal investigator, but also as an active lab member who will work in a hands-on manner to perform experiments and data analysis.  

1. Jiang H, Liu S, Geng X, Caccavano A, Conant K, Vicini S, Wu JY. Pacing Hippocampal Sharp-Wave Ripples With Weak Electric Stimulation. Frontiers in neuroscience. 2018; 12:164. PubMed [journal]PMID: 29599704 PMCID: PMC5862867
2. Sun ZY, Bozzelli PL, Caccavano A, Allen M, Balmuth J, Vicini S, Wu JY, Conant K. Disruption of perineuronal nets increases the frequency of sharp wave ripple events. Hippocampus. 2018; 28(1):42-52. NIHMSID: NIHMS906811PubMed [journal]PMID: 28921856 PMCID: PMC6047756
3. Huang X, Xu W, Liang J, Takagaki K, Gao X, Wu JY. Spiral wave dynamics in neocortex. Neuron. 2010 Dec 9;68(5):978-90. PubMed PMID: 21145009; PubMed Central PMCID: PMC4433058.
4. Xu W, Huang X, Takagaki K, Wu JY. Compression and reflection of visually evoked cortical waves. Neuron. 2007 Jul 5;55(1):119-29. PubMed PMID: 17610821; PubMed Central PMCID: PMC1988694.