PT  - JOURNAL ARTICLE
AU  - Miloslav Sedlacek
AU  - William N. Grimes
AU  - Morgan Musgrove
AU  - Amurta Nath
AU  - Hua Tian
AU  - Mrinalini Hoon
AU  - Fred Rieke
AU  - Joshua H. Singer
AU  - Jeffrey S. Diamond
TI  - Dendro-somatic synaptic inputs to ganglion cells violate receptive field and connectivity rules in the mammalian retina
AID  - 10.1101/2021.07.01.450751
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.07.01.450751
4099  - http://biorxiv.org/content/early/2021/07/01/2021.07.01.450751.short
4100  - http://biorxiv.org/content/early/2021/07/01/2021.07.01.450751.full
AB  - In retinal neurons, morphology strongly influences visual response features. Ganglion cell (GC) dendrites ramify in distinct strata of the inner plexiform layer (IPL) so that GCs responding to light increments (ON) or decrements (OFF) receive appropriate excitatory inputs. This vertical stratification prescribes response polarity and ensures consistent connectivity between cell types, whereas the lateral extent of GC dendritic arbors typically dictates receptive field (RF) size. Here, we identify circuitry in mouse retina that contradicts these conventions. A2 amacrine cells are interneurons understood to mediate “cross-over” inhibition by relaying excitatory input from the ON layer to inhibitory outputs in the OFF layer. Ultrastructural and physiological analyses show, however, that some A2s deliver powerful inhibition to OFF GC somas and proximal dendrites in the ON layer, rendering their inhibitory RFs smaller than their dendritic arbors. This OFF pathway, avoiding entirely the OFF region of the IPL, challenges several tenets of retinal circuitry.Competing Interest StatementThe authors have declared no competing interest.