Summary
This study demonstrates that avian circadian feeding rhythms are regulated by a distributed photoreceptive system encompassing retinal, pineal, and deep brain photoreceptors, each with different sensitivity thresholds. For lighting designers working with non-mammalian animals or studying extraretinal light pathways, the findings highlight that circadian entrainment can occur through multiple photoreceptive routes and is highly dependent on light intensity.
Key Findings
- Wild-type and blind (GUCY1*) chickens with head occlusion synchronized feeding rhythms to light-dark cycles at intensities >12 lux, but blind birds free-ran (period >24 h) at lower intensities.
- After head occlusion and release to constant light, blind GUCY1* birds free-ran with a period of approximately 24.5 hours, indicating residual extraretinal photoreception.
- Enucleated birds (no retinas) could synchronize feeding rhythms through brain illumination alone, but pinealectomized birds required high-intensity light (≥800 lux) for synchronization, revealing functional deep brain photoreceptors with lower sensitivity.
- Results confirm a multiple-photoreceptor system in chickens where retinal, pineal, and deep brain photoreceptors differentially contribute to circadian entrainment depending on light intensity.
Categories
Sleep & Circadian Health: Investigates photic entrainment of feeding rhythms and circadian synchronization through multiple photoreceptive systems in an avian model.
The Science of Light: Characterizes the differential contributions of retinal, pineal, and deep brain photoreceptors to light-driven circadian entrainment, with specific intensity thresholds identified.
Author(s)
DJ Valdez, PS Nieto, NM Díaz, E Garbarino Pico
Publication Year
2013
Number of Citations
23
Related Publications
Sleep & Circadian Health
- Phototransduction by retinal ganglion cells that set the circadian clock
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- The two‐process model of sleep regulation: a reappraisal
- Melanopsin is required for non-image-forming photic responses in blind mice
- Strange vision: ganglion cells as circadian photoreceptors
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
- Color appearance models
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice