Ambient illumination switches contrast preference of specific retinal processing streams

Area of Science:

• Neuroscience
• Vision Science
• Sensory Systems

Background:

• Visual scenes are encoded by ~20 retinal ganglion cell (RGC) types.
• RGCs process visual information, responding to positive (ON) or negative (OFF) contrast.
• Understanding how ambient illumination affects RGC contrast encoding is crucial for vision research.

Purpose of the Study:

• To investigate the influence of ambient illumination on contrast encoding across different RGC types.
• To identify RGC types that exhibit luminance-dependent shifts in contrast preference.
• To elucidate the mechanisms underlying these adaptive changes in contrast processing.

Main Methods:

• Utilized large-scale multielectrode array recordings in mice.
• Characterized RGC responses across five orders of magnitude in light levels.
• Mapped spatiotemporal receptive fields at varying mean light levels.

Main Results:

• Identified three RGC types (Sw1, Sw2, Sw3) that switch contrast preference based on luminance.
• Observed reversible ON(pref) to OFF(pref) shifts in Sw1 and Sw2-RGCs, and OFF(pref) to ON(pref) in Sw3-RGCs with increasing illumination.
• Found that changes in ON and OFF pathway inputs to receptive field centers drive these preference shifts.
• Demonstrated stable direction and orientation selectivity in RGCs despite contrast preference changes.

Conclusions:

• Specific RGC types dynamically adjust their contrast preference in response to ambient light levels.
• These adaptive changes are mediated by alterations in receptive field organization.
• Visual processing, including direction and orientation selectivity, remains robust across different light conditions.