Melanopsin in the circadian timing system

@article{Beaule2003MelanopsinIT,
  title={Melanopsin in the circadian timing system},
  author={Christian Beaulé and Barry Robinson and Elaine Waddington Lamont and Shimon Amir},
  journal={Journal of Molecular Neuroscience},
  year={2003},
  volume={21},
  pages={73-89}
}
In mammals, circadian rhythms are generated by a light-entrainable oscillator located in the hypothalamic suprachiasmatic nucleus (SCN). Light signals reach the SCN via a dedicated retinal pathway, the retinohypothalamic tract (RHT). One question that continues to elude scientists is whether the circadian system has its own dedicated photoreceptor or photoreceptors. It is well established that conventional photoreceptors, rods and cones, are not required for circadian photoreception, suggesting… 
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