Fig. 1.

A simplified scheme of the disturbed circadian system in PD. Reduced time cues are obtained from external zeitgebers in PD patients, due to the impaired visual acuity and disabled motor ability. Meanwhile, the internal circadian clock outputs are damaged in SCN, where the α-synuclein is accumulated. As a result, disrupted rhythm of clock genes in SCN impairs its modulation of other central and peripheral clocks, which might have negative consequences on behavioral and physiological functions. SCN, suprachiasmatic nuclei; SN, substantia nigra.