Kwoon Y. Wong, Ph.D.
Research Projects

Vision is our most important sense, enabling us to discern the identity and movement of objects in our surroundings.  But in addition to supporting such “image-forming” functions, our visual system mediates a variety of “non-image-forming” responses to environmental light.  Examples of these accessory visual responses include constriction of the pupil, synchronization of our sleep-wake cycle to the solar day, acute modulation of alertness, regulation of hormone release, and rudimentary light recognition in some blind patients.

In mammals, including humans, both types of visual processing begin in the retina.  One of the most surprising recent discoveries in neurobiology is that unlike image-forming vision, accessory vision does not require rod and cone photoreceptors.  This is because non-image-forming photoreception is mediated not only by rods and cones, but also by a rare type of ganglion cell that expresses the light-sensing molecule melanopsin and functions as a photoreceptor.  These intrinsically photosensitive retinal ganglion cells (ipRGCs) can drive robust accessory visual responses in rodents and humans that lack rods and cones. These ganglion-cell photoreceptors are also necessary for accessory visual responses: when these neurons are selectively destroyed in mouse models, all non-image-forming visual behaviors are abolished even though the rest of the retina remains intact. This suggests that ipRGCs provide the only conduit through which rod/cone signals can reach the accessory visual centers in the brain.  Thus, ganglion-cell photoreceptors play a critical role in non-image-forming vision.

Dr. Wong 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 sleep-wake cycle.  Specifically, he seeks to answer the following questions:

1. How do the ipRGCs respond to light stimuli of different wavelengths, intensities and durations? 
2. Which types of retinal neurons communicate with the ipRGCs?
3. How do the neuroactive substances released by retinal amacrine cells modulate the light response of ipRGCs? 
4. How do the ganglion cells’ output to the hypothalamic suprachiasmatic nucleus synchronize the biological clock to the solar cycle?

The techniques employed in these studies include patch-clamp recording, multi-electrode-array recording, calcium imaging and two-photon microscopy.

The long-term goal of Dr. Wong’s 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. Night time lights that minimize the harmful effects of nocturnal light exposure while supporting image-forming visual tasks such as reading
4. Pharmacologic agents and electronic devices that enhance the visual capabilities of people who are blind

Postdoctoral Research Position

A postdoctoral research position is available in Dr. Wong's laboratory. The starting date for this position is flexible, and funding is sufficient for at least four years of support. Salary will be based on the NIH scale, and fringe benefits will be included. To apply for this position, please email a CV and contact information for three references to kwoon@umich.edu.