Summary
This study identifies and characterizes retinal neuronal circuits involved in encoding absolute light irradiance, including M2 intrinsically photosensitive retinal ganglion cells (ipRGCs) and coupled amacrine cells, using a transgenic Cre mouse line. Understanding these irradiance-encoding circuits is foundational for designing lighting that effectively drives non-visual responses such as circadian entrainment and alertness.
Key Findings
- Polyaxonal amacrine cells in the GCL show sustained irradiance-encoding ON responses that persist during chemical synaptic blockade, suggesting intrinsic photosensitivity passed through gap junctions from M2 ipRGCs.
- Amacrine cell arbors spread approximately 1 mm across the retina and costratify with M2 ipRGC dendrites in the inner half of the ON sublamina of the IPL, indicating tracer coupling between these cell types.
- A novel bistratified RGC type (R-cell) encodes irradiance with ON responses but also receives OFF bipolar input, confirmed by serial blockface electron microscopic reconstruction.
- Direction-selective RGC type (RDS) innervates the nucleus of the optic tract (NOT), linking this Cre line to circuits involved in visual motion as well as irradiance encoding.
Categories
The Science of Light: This paper characterizes retinal cell types involved in irradiance encoding, including M2 ipRGCs and coupled amacrine cells, directly relevant to understanding how the retina measures absolute light intensity for circadian and other non-visual functions.
Author(s)
S Sabbah, D Berg, C Papendorp, KL Briggman
Publication Year
2017
Number of Citations
26
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