学术报告： Adaptive Control of Innate Reflexes by Visual Cortex
时 间：2018年01月25日 上午10：00-11：00
报 告 人： 刘宝华 博士 University of Toronto at Mississauga
主 持 人： 李朝晖教授
Abstract of Talk:
The mammalian visual cortex sends massive axonal projections to the brainstem, including projections to nuclei that mediate innate motor reflexes. These long-range projections represent an anatomical substrate through which visual cortex may directly influence innate behaviors. To test this hypothesis, I studied the impact of visual cortex on the optokinetic reflex (OKR), an involuntary eye movement that stabilizes images on the retina while the animal moves. Although innate, the OKR is highly plastic. This plasticity is essential to maintain image stability, since the amplitude of the OKR needs to be continuously readjusted as the animal matures, grows, ages or suffers from impairments of other ocular motor reflexes. Previously, OKR plasticity was thought to be entirely mediated by the brainstem and cerebellum. However, I discovered a prominent role of the visual cortex in this plasticity. In particular, I showed that a plastic increase in the amplitude of the OKR, induced by impairing another image stabilization mechanism, was reversed upon silencing visual cortex. Furthermore, I discovered that by selectively ablating visual cortical neurons projecting to the brainstem nuclei responsible for the OKR, I could strongly reduce OKR plasticity. Finally, I showed that OKR plasticity is generated by an enhanced drive exerted by visual cortex onto these brainstem nuclei. These results demonstrate how the innervation of a phylogenetically older structure by the neocortex can modulate and expand the performance of reflexive behaviors in an experience dependent manner.
Baohua Liu received his BEng and MSc from Nankai University(2002). He obtained his PhD degree in Physiology and Biophysics from The University of Southern California in America (2010). After his PhD study, he worked as postdoctoral fellow at University of California in America during 2011 - 2017. He was appointed as Assistant Professor in Department of Biology at University of Toronto Mississauga from 2018. His research interests include Cortical mechanism controlling innate behaviors, The role of inhibition in specifying receptive field structure in visual cortex etc. He has published papers in Nature, J. Neurosci., Nat. Neurosci. etc.