Circadian influence on brain connectivity revealed by resting-state fMRI in awake mice

Circadian rhythms control almost all our vital physiology and cognitive functions. Disruptions of circadian rhythms are also reported in multiple neuropsychiatric disorders. However, the neural network-level study of the circadian system in vivo has been understudied. Here we use awake mice resting-state fMRI to characterize the functional connectivity changes at different time points in the circadian cycle. Our results indicate that circadian oscillations can alter the functional connectivity across the brain with various changes depending on the local circuits. Particularly, the midbrain dopaminergic system showed a trend of stronger connectivity to the cortex at night compared to the morning.