Natural activity and light response of the eye’s internal clock in vertebrates

Retinal cells in vertebrates exhibit divergent capabilities for generating circadian rhythms, with photoreceptors serving as the primary rhythm source in amphibians.

• Biological clocks are distributed in various tissues and synchronized by the environmental day/night cycle.
• The retina combines photoreception and circadian oscillator functions, crucial for adapting to daily light changes.
• Different retinal cell types can generate sustained circadian rhythms, but the expression of clock genes varies among vertebrates.
• In mammals, it is suggested that all retinal cells express the molecular components of the circadian clock.
• Light synchronization mechanisms play a significant role in regulating the retinal clock's function.

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