Professor Tian Xue was born in May 1977 in Xuzhou, Jiangsu Province, China. From 2005-2012, he worked as a postdoctoral fellow and assistant researcher at the University of California, Davis and Johns Hopkins University School of Medicine, U.S.A. He has been a professor at the University of Science and Technology of China (USTC) since 2012. He has been the executive dean of the College of Life Sciences (CLCS) from 2014 to 2020, and the Executive Dean of the Department of Life Science and Medicine (DLM) from 2018-2022. Member of the Party Committee of the University of Science and Technology of China (USTC) from 2019, Director of the Department of Teachers' Work of the Party Committee and the Department of Human Resources from 2020-2022, and Assistant to the President of USTC from January 2022.

Title:Light and Life – Neuronal Mechanisms of Image-forming and Non-image-forming Vision

Abstract：

Light sensation not only provides us with the image vision perceptions, but also regulates many physiological functions, collectively known as non-image-forming vision, such as circadian rhythm, pupillary reflex, arousal, mood. But the underline neural circuits, molecular and cellular mechanisms are still elusive. There are mainly three types of photoreceptors in the mammalian retina: rods and cones and intrinsically photosensitive retinal ganglion cells (ipRGCs). It is generally believed that rods and cones mediate image-forming vision, while ipRGCs mediate non-image-forming vision.

Previously, we discovered the neurophysiological mechanisms of light-at-night induced depression; cortical synaptogenesis promoted by light sensation during infanthood. Recently, our laboratory found that light can directly influence glucose metabolism independently of circadian rhythms. We identified a neural circuit: ipRGCs in retina→hypothalamus→brainstem→brown adipose tissue (BAT), which mediates light-induced decreases in glucose metabolism by inhibiting sympathetic nervous activity. Importantly, this phenomenon and mechanism also exist in human, which may explain the many public health observations of the linkage of night-time light pollution with metabolic disorders such as obesity and diabetes.

Furthermore, we surprisingly found that the non-image-forming photoreceptor ipRGCs improves image vision orientation selectivity of mouse layer 2/3 neurons in the primary visual cortex (V1). Interestingly, we found that specific activation of ipRGCs in human subjects by visual spectrum manipulation significantly enhances human discriminability of the visual orientation. This unpublished work reveals the so-called “non-image-forming photoreceptor” working together with rods and cones to process the cortical visual features and facilitate image recognition.

All together, these works revealed that the interaction between “light and life” is much more extensive and important than we generally understood.