The Development of Circadian Rhythms in Human Infants

(Balsalobre et al., 1998, Zylka et al., 1998, Yamazaki et al., 2000). The central
pacemaker cells show their superiority as they can oscillate in medium for several
weeks at time, compared with days for peripheral oscillators as demonstrated in
Figure 1.2 (Reppert & Weaver, 2002).
In vivo, the peripheral clocks use the central clock as a main reference and time
synchroniser. The SCN is therefore sometimes referred to as a „conductor‟ to
maintain order, rhythm and keep the diurnal patterns „on cue‟ and coordinated rather
than have a haphazard and chaotic pattern, with a lack of precision (Damiola et al.,
2000, Stokkan et al., 2001, Albrecht & Eichele, 2003b).
In vitro, if temperature is adjusted or other small adaptations to the medium are made,
there are corresponding changes in peripheral gene expression, showing that the
peripheral clocks are dynamic and do not rely fully on the central pacemaker to
determine their rhythm (Balsalobre et al., 2000, Brown et al., 2002).
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