I have been studying the vertebrate visual system for my entire research career, using mainly electrophysiological and pharmacological techniques. For my PhD work with John Dowling at Harvard, I studied the first stage of image analysis, namely the synapse linking bipolar cells to their afferent rod and cone photoreceptors. I then became fascinated by a recently identified third photoreceptor, a type of retinal ganglion cells implicated in circadian entrainment, modulation of alertness, the pupil reflex, and other non-image-forming visual functions. I did six years of postdoctoral work with the discoverer of these ganglion-cell photoreceptors, David Berson at Brown University, studying these neurons' light responses and their signaling to the SCN, where light shifts the body’s circadian clock.
Since Jan 2010, I have been an assistant professor at the University of Michigan, in the Dept of Ophthalmology & Visual Sciences, and the Dept of Molecular, Cellular & Developmental Biology. My laboratory uses electrophysiological and imaging techniques to study the ganglion-cell photoreceptors as well as their interactions with other retinal neurons and with hypothalamic cells that regulate the circadian clock. Specifically, we seek to answer the following questions: 1) How do the ganglion-cell photoreceptors respond to light stimuli of different wavelengths, intensities and durations? 2) Which types of retinal neurons communicate with these novel photoreceptors? 3) How do the neuroactive substances released by retinal amacrine cells modulate the light response of ganglion-cell photoreceptor? 4) How does these ganglion cells’ output to the hypothalamus synchronize the circadian clock to the solar cycle? The techniques employed in these studies include patch-clamp recording, multielectrode-array recording, immunohistochemistry, calcium imaging and confocal microscopy.
The long-term goal of my research is to generate data that may guide the invention of: 1) drugs and light therapies for treating jet lag, sleep disorders and depression; 2) daytime lighting technologies that maximize alertness and hence productivity at work and in school; 3) nighttime lights that minimize the harmful effects of nocturnal light exposure while supporting image-forming visual tasks such as reading; and 4) pharmacological agents and electronic devices that enhance the visual capabilities of blind patients.