Year: 2026
Type: article
Abstract: Ambient luminance varies widely, and retinal output is shaped by adaptation-dependent gain control. Relative to the adaptation level, a decrease in light intensity can either return intensity toward the adaptation level or drive it farther away from that level. Whether OFF retinal outputs signal both changes simply as light-intensity decrements or distinguish them according to their relationship to the adaptation level is currently unclear. This study examined OFF sustained retinal ganglion cells in bullfrogs ( Rana catesbeiana ) of either sex and quantified response bias by comparing spike counts during decrements that moved toward and away from the adaptation level. Responses fell into two functional populations: one signaled decrements in both cases, whereas the other selectively signaled decrements that moved away from the adaptation level, indicating adaptation level-referenced encoding. Although surround suppression was considered a possible contributor to these differences, manipulations expected to reduce classical surround contributions did not explain the selective suppression of responses during decrements that moved toward the adaptation level. Blocking GABA A receptors (GABA A Rs) consistently weakened the response asymmetry between decrements that moved toward and away from the adaptation level, suggesting that GABA A R-dependent inhibition contributes to the mechanism underlying adaptation level-referenced responses. Taken together, these findings reveal a distinct computation for light-intensity decrement processing and expand the functional diversity of OFF outputs across light-intensity contexts.
Source: eNeuro
Institution: Senshu University
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,925
OpenAlex ID: W7203827543
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