Time-Specific Fear Acts as a Non-Photic Entraining Stimulus of Circadian Rhythms in Rats

Virtually all animals have endogenous clock mechanisms that “entrain” to the light-dark (LD) cycle and synchronize psychophysiological functions to optimal times for exploring resources and avoiding dangers in the environment. Such circadian rhythms are vital to human mental health, but it is unknow...

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Bibliographic Details
Published in:Scientific reports 2015-10, Vol.5 (1), p.14916-14916, Article 14916
Main Authors: Pellman, Blake A., Kim, Earnest, Reilly, Melissa, Kashima, James, Motch, Oleksiy, de la Iglesia, Horacio O., Kim, Jeansok J.
Format: Article
Language:English
Subjects:
631/158/856
631/378/1385/2640
631/378/1457/1284
Amygdala
Amygdala - physiology
Animal behavior
Animals
Behavior, Animal
Biological clocks
Circadian Rhythm
Circadian rhythms
Cues
Entrainment
Fear
Feeding Behavior
Footshock
Foraging behavior
Humanities and Social Sciences
Mental health
multidisciplinary
Nocturnal
Photoperiod
Physical Stimulation
Rats
Resource exploration
Rodents
Science
Suprachiasmatic nucleus
Suprachiasmatic Nucleus - pathology
Suprachiasmatic Nucleus - physiology
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Summary:Virtually all animals have endogenous clock mechanisms that “entrain” to the light-dark (LD) cycle and synchronize psychophysiological functions to optimal times for exploring resources and avoiding dangers in the environment. Such circadian rhythms are vital to human mental health, but it is unknown whether circadian rhythms “entrained” to the LD cycle can be overridden by entrainment to daily recurring threats. We show that unsignaled nocturnal footshock caused rats living in an “ethological” apparatus to switch their natural foraging behavior from the dark to the light phase and that this switch was maintained as a free-running circadian rhythm upon removal of light cues and footshocks. Furthermore, this fear-entrained circadian behavior was dependent on an intact amygdala and suprachiasmatic nucleus. Thus, time-specific fear can act as a non-photic entraining stimulus for the circadian system and limbic centers encoding aversive information are likely part of the circadian oscillator network that temporally organizes behavior.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep14916