Hierarchical retinal computations rely on hybrid chemical-electrical signaling

Date

2023

Authors

Hanson, Laura
Ravi-Chander, Prathyusha
Berson, David
Awatramani, Gautam B.

Journal Title

Journal ISSN

Volume Title

Publisher

Cell Reports

Abstract

Summary: Bipolar cells (BCs) are integral to the retinal circuits that extract diverse features from the visual environment. They bridge photoreceptors to ganglion cells, the source of retinal output. Understanding how such circuits encode visual features requires an accounting of the mechanisms that control glutamate release from bipolar cell axons. Here, we demonstrate orientation selectivity in a specific genetically identifiable type of mouse bipolar cell—type 5A (BC5A). Their synaptic terminals respond best when stimulated with vertical bars that are far larger than their dendritic fields. We provide evidence that this selectivity involves enhanced excitation for vertical stimuli that requires gap junctional coupling through connexin36. We also show that this orientation selectivity is detectable postsynaptically in direction-selective ganglion cells, which were not previously thought to be selective for orientation. Together, these results demonstrate how multiple features are extracted by a single hierarchical network, engaging distinct electrical and chemical synaptic pathways.

Description

We would like to thank Dr. Marla Feller for TRHR-EGFP mice and Dr. David Paul for the Gjd2fl/fl mice, Dr. Jamie Boyd and Dr. Benjamin Murphy-Baum for their help with 2P imaging and analysis software (IGOR, Wavemetrics), Mike Delsey for technical support, and Tracy Michaels for assistance with animal care and breeding.

Keywords

orientation selectivity, direction selectivity, bipolar cell, gap junction, retina, wide-field amacrine cell, direction-selective ganglion cell

Citation

Hanson, L., Ravi-Chander, P., Berson, D., Awatramani, G. B. (2023). Hierarchical retinal computations rely on hybrid chemical-electrical signaling. Cell Reports, 42(2), 112030. https://doi.org/10.1016/j.celrep.2023.112030.