Diurnal variability of human operator attention disengagement and chronotype: an fMRI-based case study

Abstract

The main objective of this study was to analyse diurnal variations during attention disengagement operations on a neuronal level in a group of subjects representing extreme chronotypes. The parietal lobes of the participants were scanned four times per day for activity changes using functional magnetic resonance imaging (fMRI), while the subjects performed the task at hand. The findings provide credible evidence of the existence of variability in the activity patterns and levels of the parietal lobes. The activity patterns and levels depend on both the participants’ chronotype as well as time of day. The morning type showed stronger activation of the left parietal lobe, while the evening type showed stronger activation of the right parietal lobe. There was a visible decrease in parietal lobe activity during the post-lunch dip, independent of the subjects’ chronotype. Such variability of parietal lobe activity may suggest that humans are more likely to make errors during task performance at certain times of the day as opposed to others.

Keywords:

• human attention
• fMRI
• parietal lobe activity
• diurnal variability
• chronotype

Acknowledgements

This work was supported by a grant from the Polish Ministry of Science and Higher Education (N106 034 31/3110) (2006–2009) and a grant from the Faculty of Management and Social Communication at Jagiellonian University (WZKS-30/81/06/07). We would like to thank Iza Gatkowska, Barbara Sobiecka, Justyna Kozub and Adam Swierczyna for assistance in fMRI data acquisition. The authors would like to thank two anonymous reviewers for their insightful comments on the earlier version of the manuscript.