Neuroanatomy Draw It To Know It

25. Sleep and Wakefulness 441

Flip-Flop Switch ( Advanced )

■ Th e arousal center inhibits the sleep center.
■ Th e orexigenic cells stabilize the arousal center.
■ Th e sleep center inhibits the arousal center and also
the orexigenic cells.

■ Orexins are produced by a discrete neuronal

population within the lateral hypothalamus.

■ Loss of orexin results in the clinical condition of

n a r c o l e p s y w i t h c a t a p l e x y.

Th

D

Hy

N. oculamet

a Aq

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FIGURE 25-1 Von Economo’s clinical–pathologic correlation for the sleep and wakefulness centers. Th e center for sleep is designated by horizontal
lines and the center for wakefulness is designated by vertical (diagonal) lines. Used with permission from Economo, Constantin von. “Sleep as a Problem
of Localization.” Th e Journal of Nervous and Mental Disease 71, no. 3 (1930).