Architecture of retinal projections to the central circadian pacemaker

Diego Carlos Fernandez, Yi Ting Chang, Samer Hattar, Shih Kuo Chen

Research output: Contribution to journalArticle

Abstract

The suprachiasmatic nucleus (SCN) receives direct retinal input from the intrinsically photosensitive retinal ganglion cells (ipRGCs) for circadian photoentrainment. Interestingly, the SCN is the only brain region that receives equal inputs from the left and right eyes. Despite morphological assessments showing that axonal fibersoriginating from ipRGCs cover the entire SCN, physiological evidence suggests that only vasoactive intestinal polypeptide (VIP)/ gastrin-releasing peptide (GRP) cells located ventrally in the SCN receive retinal input. It is still unclear, therefore, which subpopulation of SCN neurons receives synaptic input from the retina and how the SCN receives equal inputs from both eyes. Here, using single ipRGC axonal tracing and a confocal microscopic analysis in mice,we show that ipRGCs have elaborate innervation patterns throughout the entire SCN. Unlike conventional retinal ganglion cells (RGCs) that innervate visual targets either ipsilaterally or contralaterally, a single ipRGC can bilaterally innervate the SCN. ipRGCs form synaptic contacts with major peptidergic cells of the SCN, including VIP, GRP, and arginine vasopressin (AVP) neurons, with each ipRGC innervating specific subdomains of the SCN. Furthermore, a single SCNprojecting ipRGC can send collateral inputs to many other brain regions. However, the size and complexity of the axonal arborizations in non-SCN regions are less elaborate than those in the SCN. Our results provide a better understanding of how retinal neurons connect to the central circadian pacemaker to synchronize endogenous circadian clocks with the solar day.

Original languageEnglish (US)
Pages (from-to)6047-6052
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number21
DOIs
StatePublished - May 24 2016

Fingerprint

Suprachiasmatic Nucleus
Retinal Ganglion Cells
Gastrin-Releasing Peptide
Vasoactive Intestinal Peptide
Retinal Neurons
Neurons
Circadian Clocks
Arginine Vasopressin
Brain
Cell Nucleus
Retina

Keywords

  • Circadian
  • IpRGCs
  • Melanopsin
  • Non-image forming functions
  • Suprachiasmatic nucleus

ASJC Scopus subject areas

  • General

Cite this

Architecture of retinal projections to the central circadian pacemaker. / Fernandez, Diego Carlos; Chang, Yi Ting; Hattar, Samer; Chen, Shih Kuo.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 113, No. 21, 24.05.2016, p. 6047-6052.

Research output: Contribution to journalArticle

Fernandez, Diego Carlos ; Chang, Yi Ting ; Hattar, Samer ; Chen, Shih Kuo. / Architecture of retinal projections to the central circadian pacemaker. In: Proceedings of the National Academy of Sciences of the United States of America. 2016 ; Vol. 113, No. 21. pp. 6047-6052.
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