Neural Circuits Underlying Circadian Photoreception

Abstract

Light is an important environmental signal that affects many different aspects of physiology and behavior to allow organisms to both predict and respond to their surroundings. For example, light influences the timing of biological clocks or circadian rhythms. Although circadian rhythms are endogenous and persist in the absence of environmental cues, they can be reset or entrained by light and other environmental signals. In addition to circadian rhythms, other aspects of biology such as neuroendocrine function, mood, alertness, and cognition are also influenced by light. Therefore, the timing, duration, and quality of light plays an important role in maintaining physical and mental health. Although these light-driven circuits evolved in a natural light-dark cycle, electrical lighting and urbanization have reduced human light exposure during the day and increased light exposure at night. This pattern of light exposure has negatively impacted human health and performance. The goal of my thesis is to contribute to understanding these light-driven circuits, which could be used to advise the use of light to mitigate negative effects of the modern light environment.