What is a Actogram?
Actogram: A graphical representation of an organism’s phases of activity and rest over the course of a day. Aftereffect: Ongoing characteristics of a rhythm (altered phasing, period length, or amplitude) resulting from previous stimulation.
What is an endogenous rhythm?
Endogenous rhythm is the term used in describing biological processes which alter periodically although external conditions remain constant. The movement of a pendulum is analogous to a biological endogenous rhythm.
What is the most powerful Zeitgeber?
Light is considered the strongest Zeitgeber for the SCN. Thus, resetting of the circadian system by light exposure at most times during the subjective day has little or no effect on the resetting of the clock.
What is entrainment in biology?
Entrainment is the synchronization or alignment of the internal biological clock rhythm, including its phase and period, to external time cues, such as the natural dark-light cycle.
Why are Actograms double plotted?
(B) To better visualize behavioral rhythms, actograms are often double plotted by aligning two consecutive days horizontally (e.g. day 1 left and day 2 right).
What is an exogenous rhythm?
Exogenous rhythm refers to environmental factors that influence natural circadian rhythm cycles within a twenty-four period including light exposure, temperature, ambient noise, regular diet, different time zones, traumatic events, injuries, and occupational stress.
What is an example of Infradian rhythm?
Some examples of infradian rhythms in mammals include menstruation, breeding, migration, hibernation, molting and fur or hair growth, and tidal or seasonal rhythms. In contrast, ultradian rhythms have periods shorter than the period of a circadian rhythm.
How does light reset the SCN?
Light resets the oscillations in the SCN through a mechanism involving melanopsin-containing retinal ganglion cells that project directly to the SCN via the retino-hypothalamic tract. Thus, light input and the circadian system work together to modulate properties of the sleep–wake cycle.
Why is there a need for Zeitgebers?
Zeitgeber are Your Body’s Timekeeper. Zeitgebers are cues given by the environment that reset the circadian rhythm. These external cues reset the internal body clock, also known as your circadian rhythm. Naturally occurring sunlight is the strongest zeitgeber because of its impact on hormones like melatonin.
What is behavioral entrainment?
Entrainment is defined as the adjustment or moderation of one behavior either to synchronize or to. be in rhythm with another behavior.
Which are the two types of behavioral entrainment?
There are two general modes of entrainment: phasic and continuous. The phasic mode is when there is limited interaction with the environment to “reset” the clock every day by the amount equal to the “error”, which is the difference between the environmental cycle and the organism’s circadian rhythm.
How is animal activity represented in an actogram?
In Actograms, animal activity (e.g. use of running wheel) is represented as bars. These bars are placed within a 24 hour timeframe so we can see rhythms. Sometimes the graph is duplicated (as with the example 4x) so we can see a pattern easily.
What does the bar at the top of the actogram mean?
The circles indicate high tide, which occurs every 12.4 hours, while the bar at the top of the page indicates sunrise and sunset. The actogram represents a rhythm of activity initially entrained to a LD 12:12 light cycle (12 hours light 12 hours dark).
What is the meaning of double plotted actogram?
Double-Plotted (Actogram): An actogram in which the values on the x-axis range over two Zeitgeber-cycles (usually, 24h+24h=48h), resulting in a duplication of displayed data. Empirical: Having to do with observable results; grounded in experience.