Abstract
Local and global forms of inhibition controlling directionally selective ganglion cells (DSGCs) in the mammalian retina are well documented. It is established that local inhibition arising from GABAergic starburst amacrine cells (SACs) strongly contributesto direction selectivity. Here, we demonstrate thatincreasing ambient illumination leads to the recruitment of GABAergic wide-field amacrine cells (WACs) endowing the DS circuit with an additional feature: size selectivity. Using a combination of electrophysiology, pharmacology, and light/electron microscopy, we show that WACs predominantly contact presynaptic bipolar cells, which drive direct excitation and feedforward inhibition (through SACs) to DSGCs, thus maintaining the appropriate balance of inhibition/excitation required for generating DS. This circuit arrangement permits high-fidelitydirection coding over a range of ambient lightlevels, over which size selectivity is adjusted. Together, these results provide novel insights into the anatomical and functional arrangement of multiple inhibitory interneurons within a single computational module in the retina.
Original language | English (US) |
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Pages (from-to) | 276-291 |
Number of pages | 16 |
Journal | Neuron |
Volume | 86 |
Issue number | 1 |
DOIs | |
State | Published - Apr 8 2015 |
Funding
We thank K. Delaney and B. Chow for their useful discussions, J. Boyd (University of British Columbia) for help with 2-photon imaging software, A. Sullivan and A. Nanda for providing helpful technical support, and T. MacKellar for help with morphological reconstructions. This work was supported by the Marguerite Adamson Estate Fund (A.H. and A.J.M.) and operating grants from the Foundation Fighting Blindness (Canada) and Canadian Institutes for Health Research (CIHR- 130268-2013) awarded to G.B.A.
ASJC Scopus subject areas
- General Neuroscience