Chronotype Predicts Activity Patterns in the Neural Underpinnings of the Motor System During the Day

Abstract

Neuroimaging is increasingly used to study the motor system in vivo. Despite many reports of time-of-day influences on motor function at the behavioral level, little is known about these influences on neural motor networks and their activations recorded in neuroimaging. Using functional magnetic resonance imaging (fMRI), the authors studied 15 healthy subjects (9 females; mean ± SD age: 23 ± 3 yrs) performing a self-paced finger-tapping task at different times of day (morning, midday, afternoon, and evening). Blood-oxygenation-level-dependent signal showed systematic differences across the day in task-related motor areas of the brain, specifically in the supplementary motor area, parietal cortex, and rolandic operculum (p_corr < .0125). The authors found that these time-of-day-dependent hemodynamic modulations are associated with chronotype and not with homeostatic sleep pressure. These results show that consideration of time-of-day for the analysis of fMRI studies is imperative. (Author correspondence: [email protected])

Keywords:

• Chronotype
• Circadian
• Functional magnetic resonance imaging
• Motor network
• Self-paced finger tapping
• Time-of-day

ACKNOWLEDGMENTS

This study was supported by the research scholarship of Elite Network of Bavaria to I.P., by LMU FoeFoLe Grant (grant no. 651) to J.B. and by the FP6 program EUCLOCK. The authors thank Petra Carl for excellent organizational assistance and Joachim Hermsdoerfer and Eduard Kraft for very helpful comments.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.