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. 2017 Oct 20;8:541. doi: 10.3389/fneur.2017.00541

Figure 1.

Figure 1

(A) Putative light mechanisms on human cardiovascular system via the suprachiasmatic nuclei (SCN). Human SCN potentially sends different projections to different parts of the PVN to inhibit melatonin in the pineal gland, while stimulating most other SCN-driven rhythms (e.g., HR and cortisol) after light exposure. BP, blood pressure; BT, body temperature; Cort, cortisol; HR, heart rate; Mel, melatonin; PVN, paraventricular hypothalamus nucleus; SCG, superior cervical ganglion; StelG, stellate ganglion; Vasoconstr & UCP, vasoconstriction and uncoupling protein. Continuous lines: active pathways, dotted lines: suppressed pathways. “Plus” signs: stimulation; “minus” signs: inhibition. Reproduced with permission from Scheer et al. (42). (B) Putative sympathetic and parasympathetic outputs from the SCN to peripheral organs via neurons of the rat brainstem. DMV, dorsal motor nucleus of the vagus; IML, intermediolateral spinal cord column. Red lines: parasympathetic output. Green lines: Sympathetic output. Dashed red and green lines correspond to potential output pathways. Modified from Kalsbeek et al. (34).