Introduction
The retina of the eye in vertebrates is an extension of the brain, formed embryonically from neural tissue and connected to the brain through the optic nerve. The retina contains five types of neurons, including rod and cone photoreceptors, horizontal cells, bipolar cells, amacrine cells, and retinal ganglion cells. Rods and cones convert light into electrical signal that is transmitted from bipolar cells to retinal ganglion cells and then to the brain, forming the conventional excitatory neural pathway. This signaling pathway, shaped by lateral inhibition provided by horizontal cells and amacrine cells, generates image-forming vision. In addition, a subset of retinal ganglion cells expresses the melanopsin photopigment that directly responds to visible light. The intrinsically photosensitive retinal ganglion cells (ipRGCs) project to the midbrain that control pupil reflex and circadian rhythms (non-image-forming visual responses). ipRGCs also project back to the outer retina, forming a retrograde intra-retinal signaling pathway. Moreover, retinal neurodegeneration and cell death are associated with retinitis pigmentosa, diabetic retinopathy, retinopathy of prematurity, glaucoma, myopia, and Parkinson's disease, which causes low vision and even blindness. Currently, there are no cures for those diseases.
Research goal
To understand how retinal neurons develop and function under normal conditions and how they degenerate and become dysfunctional under diseased conditions.
Research projects
Determine how starburst amacrine cells generate spontaneous retinal activity and propagate it across the retina, termed “cholinergic retinal waves”, before the onset of visual experience as well as how cholinergic retinal waves drive dopamine release from dopaminergic amacrine cells, mediating eye development.
Define the cellular and molecular mechanisms of how ipRGCs drive dopaminergic amacrine cells in the retrograde intraretinal signaling pathways.
Access photopic rod-mediated responses and identify the neural pathways and function of rod-mediated responses in daylight conditions.
Determine impairments of visual signaling pathways following oxygen-induced retinopathy and its impact on the development of myopia.
Impact
The broader impact of the work will advance the understanding of the development and function of retinal neurons and enable the rational discovery of new preventive, therapeutic interventions to combat eye disorders.
Research support
National Institute of Health (National Eye Institute)
Mid-West Eyebanks
Research Excellence Fund (Oakland University)