Skip to content

Construct: Circadian Rhythms

RDoC Classification

Domain: Arousal and Regulatory Systems

Description

Circadian Rhythms are endogenous self-sustaining oscillations that organize the timing of biological systems to optimize physiology and behavior, and health. Circadian Rhythms:

  1. Are synchronized by recurring environmental cues;
  2. Anticipate the external environment;
  3. Allow effective response to challenges and opportunities in the physical and social environment;
  4. Modulate homeostasis within the brain and other (central/peripheral) systems, tissues and organs;
  5. Are evident across levels of organization including molecules, cells, circuits, systems, organisms, and social systems.

Molecules

Input

5HT Dopamine GABA Glutamate Melanopsin NPY PACAP Substance P

SCN Synchronizing and Modulating Agents

AVP Calbindin cAMP cGMP NO Steroid hormones VIP

Output

AVP Cortisol GABA Melatonin VIP

Cells

Fibroblasts ipRGC medium spiny neurons Pars tuberalis cells Pineal cells rods and cones SCN “clock” cells

Circuits

Input

Raphe to SCN projection Retinal cells Retino-hypothalamic tract Retinogeniculate tract

Output

Basolateral amygdala/ Hippocampus Central extended amygdala (central nucleus of the amygdala / Bed nucleus of the stria terminalis) HPA axis Hypothalamic neuroendocrine cell groups Hypothalamic orexin projections PVN, DMH, subparaventricular zone, PVT SCN/PVN/SCG/pineal Sympathetic / parasympathetic nervous system

Intrinsic to SCN

Suprachiasmatic nucleus (SCN) core/shell

Seasonal

SCN/PVN/SCG/pineal

Physiology

Gene expression Neural activity Neural transmitters

Behavior

Drive-regulated behaviors Locomotor activity Masking Neurobehavioral functions Sleep-rated and waking behaviors Sleep-wake

Self-Report

Diary-based measures of daily regularity/ rhythmicity (e.g., Social Rhythm Metric) Morningness-Eveningness Questionnaire Munich Chronotype Questionnaire Phase, diurnal preference, chronotype (e.g., Horne-Ostberg, CTQ) Sleepiness, alertness, well-being, mood

Paradigms

Dim Light Melatonin Onset (DLMO, phase estimate) Longitudinal Actigraphy

Genetic Approaches – genome-wide association study, candidate gene, epigenomics, circadian genomics (temporal gene expression), mutagenesis, gene targeting, quantitative trait loci.