Phase Shifts and Phase Response Curves

The circadian clock is not equally sensitive to a given zeitgeber at all times of day. This fact is a conserved feature in all examined taxa and is graphically summarized in a phase response curve (PRC), shown in Fig. 3, which plots the magnitude and direction of a phase shift as a function of the circadian phase at which a stimulus is applied. The PRC models the mechanisms by which the circadian clock is entrained to environmental cycles. For example, PRCs to light stimuli illustrate the differential effects of light at different circadian phases. Light, the principal environmental zeitgeber, has its greatest effect on the circadian clock when delivered during the subjective night, the time when a species is normally exposed to darkness. Light pulses will phase-delay rhythms in the early subjective night and phase-advance rhythms in the late subjective night. Little phase shifting occurs during the subjective day—the dead zone. These

All About Alzheimers

All About Alzheimers

The comprehensive new ebook All About Alzheimers puts everything into perspective. Youll gain insight and awareness into the disease. Learn how to maintain the patients emotional health. Discover tactics you can use to deal with constant life changes. Find out how counselors can help, and when they should intervene. Learn safety precautions that can protect you, your family and your loved one. All About Alzheimers will truly empower you.

Get My Free Ebook


Post a comment