# Signal Processing in the Inner Retina

> **NIH NIH R01** · NORTHWESTERN UNIVERSITY · 2022 · $511,133

## Abstract

The mammalian retina contains at least 40 types of retinal ganglion cells (RGCs) each tuned to respond best
to different and sometimes complex features in a visual scene. Together, these diverse RGC responses
provide us with all of the information that we use to navigate in the visual world. Each type of RGC monitors a
patch on the retinal surface, its receptive field, by collecting inputs from presynaptic bipolar and amacrine cells
of which there are more than 12 and 50 types, respectively. While the general patterns of amacrine and
bipolar cell connectivity that contribute to RGC light responses are known, the daunting complexity of the inner
synaptic layer of the retina has impeded our understanding of the connections that underlie the tuning
properties that distinguish the RGC types. Specifically, there is currently no systematic way to identify all of the
cells that make presynaptic inputs to an RGC and at the same time study their combined function as a
processing unit. This proposal uses a toolbox of viral techniques to trace and functionally characterize the
amacrine and bipolar cells that provide input to specific RGCs in both the rod dominant mouse and cone
dominant ground squirrel retinas. In three specific aims, our goals are to: 1) use a trans-synaptic rabies virus
that expresses GFP to map the direct bipolar and amacrine cell inputs to genetically targeted RGCs in the
mouse retina; 2) use a trans-synaptic rabies virus that expresses the Ca2+ indicator protein GCaMP6 to study
the functional connections between RGCs and their direct inputs from bipolar and amacrine cells in the mouse
retina; and, 3) identify and functionally characterize the inner retinal circuits responsible for blue/green color
opponent vision in the ground squirrel. Our work will define the wiring and functions of specific inner retinal
circuits in health and provide the background for understanding circuit changes that are known to occur
following photoreceptor degeneration, whether from genetic or age-onset disease.

## Key facts

- **NIH application ID:** 10475770
- **Project number:** 5R01EY018204-12
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** Steven H DeVries
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $511,133
- **Award type:** 5
- **Project period:** 2007-05-07 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10475770

## Citation

> US National Institutes of Health, RePORTER application 10475770, Signal Processing in the Inner Retina (5R01EY018204-12). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10475770. Licensed CC0.

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