Realistic retinal modeling unravels the differential role of excitation and inhibition to starburst amacrine cells in direction selectivity

PLoS Comput Biol. 2021 Dec 30;17(12):e1009754. doi: 10.1371/journal.pcbi.1009754. eCollection 2021 Dec.

Abstract

Retinal direction-selectivity originates in starburst amacrine cells (SACs), which display a centrifugal preference, responding with greater depolarization to a stimulus expanding from soma to dendrites than to a collapsing stimulus. Various mechanisms were hypothesized to underlie SAC centrifugal preference, but dissociating them is experimentally challenging and the mechanisms remain debatable. To address this issue, we developed the Retinal Stimulation Modeling Environment (RSME), a multifaceted data-driven retinal model that encompasses detailed neuronal morphology and biophysical properties, retina-tailored connectivity scheme and visual input. Using a genetic algorithm, we demonstrated that spatiotemporally diverse excitatory inputs-sustained in the proximal and transient in the distal processes-are sufficient to generate experimentally validated centrifugal preference in a single SAC. Reversing these input kinetics did not produce any centrifugal-preferring SAC. We then explored the contribution of SAC-SAC inhibitory connections in establishing the centrifugal preference. SAC inhibitory network enhanced the centrifugal preference, but failed to generate it in its absence. Embedding a direction selective ganglion cell (DSGC) in a SAC network showed that the known SAC-DSGC asymmetric connectivity by itself produces direction selectivity. Still, this selectivity is sharpened in a centrifugal-preferring SAC network. Finally, we use RSME to demonstrate the contribution of SAC-SAC inhibitory connections in mediating direction selectivity and recapitulate recent experimental findings. Thus, using RSME, we obtained a mechanistic understanding of SACs' centrifugal preference and its contribution to direction selectivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Amacrine Cells / physiology*
  • Animals
  • Computational Biology
  • Mice
  • Models, Neurological*
  • Retina / physiology*
  • Retinal Ganglion Cells / physiology*
  • Visual Pathways / physiology*

Grants and funding

We acknowledge support from the European Research Council (ERC starter grant No. 757732; https://erc.europa.eu/; M.R.E), the Israel Science Foundation (grants 1396/15 and 2449/20; https://www.isf.org.il/#/; M.R.E) and the Minerva Foundation with funding from the Federal German Ministry for Education and Research (M.R.E). We also acknowledge support from the Charles and David Wolfson Charitable Trust (M.R.E); Rolf Wiklund and Alice Wiklund Parkinson’s Disease Research Fund (M.R.E); Consolidated Anti-Aging Foundation (M.R.E); Dr. Daniel C. Andreae (M.R.E). L.A. is supported by ISEF, O.A. was supported by the ETH domain for the Blue Brain Project. M.R.E. is incumbent of the Sara Lee Schupf Family Chair. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.