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. Author manuscript; available in PMC: 2015 Jan 1.
Published in final edited form as: Front Neuroendocrinol. 2013 Oct 21;35(1):76–88. doi: 10.1016/j.yfrne.2013.10.002

Figure 3.

Figure 3

A chorus of clocks. The coordination of circadian and circannual patterns of behavior and physiology is the composite of multiple circadian oscillators and their interactions. At the core are circadian pacemakers in the pineal gland and suprachiasmatic nuclei (SCN), whose interactions maintain each other’s stability and self-sustainment through mutually inhibitory activity. Each of these pacemakers may influence downstream processes through entrainment of circadian oscillators controlling and residing in brain (e.g. song, vision and migration) and peripheral (e.g. liver, heart, muscle) function. In birds, regulation of primary gonadal activity has been separated from this circadian system with circadian oscillators residing in the mediobasal hypothalamus itself. There is little evidence that these oscillators are affected by pineal melatonin, but it is an open question whether SCM oscillators influence MBH function in the circadian and seasonal control of reproduction.