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Abstract
Understanding the molecular and genetic identity of neuron types is prerequisite to tractable control
and investigation of the behavioral relevance of discrete neuronal types. In the retina, a portion of
retinal ganglion cells (RGCs), express the light-sensitive protein melanopsin, allowing them to detect
light independent of rod and cone photoreceptors. These intrinsically photosensitive retinal ganglion
cells (ipRGCs), detect light information and transmit the encoded information to brain areas responsible
for nonimage forming behaviors, like circadian entrainment, pupillary light reflex, hormone regulation,
and sleep. IpRGCs can be divided into types, based upon differences in their morphology, light
responses, and brain projections. Understanding the specific functions and contributions of ipRGC types
is critical to our understanding of physiology.
This dissertation describes the investigation and characterization of a unique population of retinal
ganglion cells, which are labeled in a glycine transporter 2 transgenic mouse line (Glyt2
Cre) and restricted to the dorsal retina. The experiments aimed to extend these findings by employing various advanced
techniques to label and characterize these cells, including patch-clamp electrophysiology, intersectional
genetic labeling, single-cell reverse transcriptase PCR, and fluorescence in situ hybridization (FISH). The
initial focus was on validating the expression of Slc6a5 (Glyt2) mRNA in ipRGCs. The evolution of these
techniques shifted emphasis toward combining FISH with transgenic reporter lines to label and spatially
resolve RGC subtypes across entire retinas. This approach was further applied to identify ipRGC subtypes
in non-human primate (NHP) retina, providing broader insights into the molecular identity, spatial
distribution, and function of RGC subtypes.