A Central Role for Mixed Acetylcholine/GABA Transmission in Direction Coding in the Retina

Santhosh Sethuramanujam, Amanda J. McLaughlin, Geoffery deRosenroll, Alex Hoggarth, David J. Schwab, Gautam B. Awatramani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

A surprisingly large number of neurons throughout the brain are endowed with the ability to co-release both a fast excitatory and inhibitory transmitter. The computational benefits of dual transmitter release, however, remain poorly understood. Here, we address the role of co-transmission of acetylcholine (ACh) and GABA from starburst amacrine cells (SACs) to direction-selective ganglion cells (DSGCs). Using a combination of pharmacology, optogenetics, and linear regression methods, we estimated the spatiotemporal profiles of GABA, ACh, and glutamate receptor-mediated synaptic activity in DSGCs evoked by motion. We found that ACh initiates responses to motion in natural scenes or under low-contrast conditions. In contrast, classical glutamatergic pathways play a secondary role, amplifying cholinergic responses via NMDA receptor activation. Furthermore, under these conditions, the network of SACs differentially transmits ACh and GABA to DSGCs in a directional manner. Thus, mixed transmission plays a central role in shaping directional responses of DSGCs.

Original languageEnglish (US)
Pages (from-to)1243-1256
Number of pages14
JournalNeuron
Volume90
Issue number6
DOIs
StatePublished - Jun 15 2016

ASJC Scopus subject areas

  • Neuroscience(all)

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