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Researcher | Research Overview

Our lab asks how light drives functions that are as diverse as visual perception, sleep regulation, hormonal control, and setting of the internal body clock. We pose this question for species that occupy distinct ecological niches to learn how visual mechanisms are tailored to different behavioral needs. Our research spans organizational levels and time scales, from molecules to circuits and from milliseconds to hours. It centers on electrophysiological and optical techniques that are applied in vitro and in vivo.

Visual performance is remarkable. Perception can be elicited by a handful of photons, yet continues when the light level has intensified by many orders of magnitude. How is this dynamic range established? In cases of severe blindness where visual awareness is lost, light can still keep the body clock and hormone levels in register with the solar cycle. What are the origins of this robustness?

Questions of dynamic range, robustness, and other parameters of system operation recur throughout the biological sciences. We pose them in the visual system, where the input (light) can be precisely controlled and its effects can be quantified at levels ranging from the conformational changes of molecules to alterations in behavior. We seek connections between these levels.

We focus on two aspects of the visual system. The first is the fovea, a retinal specialization that initiates most visual perception in humans and other primates but is found in no other mammal. We seek to understand how the fovea supports the exceptional visual acuity of primates, which is 10-fold higher than that of cats and 100-fold higher than that of mice. The second concerns unusual photoreceptors; these are not the classical rods and cones, but a population of retinal output neurons that capture light with a molecule called melanopsin. Signals from these intrinsically photosensitive retinal ganglion cells (ipRGCs) largely bypass consciousness while exerting a broad influence on physiology. We study the mechanisms of signal generation by ipRGCs and interpret them in the context of downstream circuits in the retina and brain.

An understanding of the visual system provides the foundation for maintaining its health, detecting disease, and developing methods to forestall and reverse blindness.

Researcher | Research Background

Michael Tri H. Do is a member of the F.M. Kirby Neurobiology Center at Boston Children's Hospital and an Assistant Professor of Neurology at Harvard Medical School. His postdoctoral work, done with King-Wai Yau at the Johns Hopkins University School of Medicine, concerned an unusual type of mammalian photoreceptor that sends information directly from the retina to the brain. He completed his Ph.D. with Bruce Bean at Harvard Medical School, investigating the origin of electrical activity in certain cells of the basal ganglia. As an undergraduate at Georgetown University, he worked with Susette Mueller to learn how some types of cancer cells grow and spread more effectively than others.


Researcher | Publications