Basic mechanisms of Process C
Research has uncovered core molecular clock machinery responsive to process-C in most tissues! The bilateral or paired SCN of the hypothalamus are regarded as the sole master 24-hour pacemaker. Research has shown the circadian process to be a hierarchy of oscillations starting with oscillations from the SCN centrally emanating to the periphery—that is, downstream oscillations within the brain and then to peripheral tissues. Interactions between several hypothalamic nuclei are also involved in process-C. Importantly, SCN timing is genetically determined to be slightly > 24 hours and must be modified or reset (synchronized) to the 24-hour day–night cycle by environmental stimuli ( zeitgebers , German for “time givers” or “time cues”). The brain is employing these mechanisms to adjust to and optimize systematic function according to the location of the body.