The underlying parameters of cognitive function and human brain physiology are associated with chronotypes

Salehinejad, MA, Wischnewski, M., Ghanavati, E., et al. Underlying parameters of cognitive function and human brain physiology are associated with chronotype. nat commun 12, 4672 (2021). https://doi.org/10.1038/s41467-021-24885-0

Commentary

There is a natural relative variation in human circadian rhythms called the "chronotype".

People whose chronotype is morning or evening, for example, are characterized by certain physiological, behavioral, and genetic symptoms. However, whether and how chronotype modulates human brain physiology and cognition is not well understood, so this study was designed to investigate how cortical excitability, neuroplasticity, and cognition relate to chronotype in early and late chronotyped individuals.

Motor cortex excitability, neuroplasticity elicited by brain stimulation were monitored, and motor learning and cognitive function were examined at times when circadian rhythms were favorable and unfavorable for 32 individuals.

Motor learning and cognitive performance (working memory, attention) were reported to be greatly enhanced by circadian rhythms, along with electrophysiological factors. This outperformance is associated with enhanced cortical excitability (marked cortical facilitation, reduced cortical inhibition) and plasticity such as long-term potentiation/depression.

The results of this study provided insight into how chronotypes can modulate human brain function, from basic physiological mechanisms to behavior and higher-order cognition.