The entrainment of circadian rhythms by visual zeitgebers is mediated by
A) part of the optic nerve.
B) the retinohypothalamic tract.
C) a rare type of retinal ganglion cell.
D) all of the above
E) both A and C
Question 2
The diurnal light-dark cycle entrains the sleep-wake cycle via the
A) REM-sleep circuits.
B) cortex.
C) retinohypothalamic tracts.
D) caudal brain stem.
E) reticular formation.