Human fronto-parietal response scattering subserves vigilance at night

Area of Science:

• Neuroscience
• Cognitive Science
• Sleep Research

Background:

• Sleep deprivation significantly degrades vigilance and increases errors, particularly during circadian night hours.
• Previous research links reduced vigilance to impaired fronto-parietal functional connectivity, but effective connectivity remains unexamined during sustained wakefulness.
• No studies have concurrently assessed brain effective connectivity and vigilance changes during prolonged wakefulness.

Purpose of the Study:

• To investigate fronto-parietal effective connectivity changes during 29 hours of sustained wakefulness.
• To examine the relationship between fronto-parietal effective connectivity and vigilance performance during prolonged wakefulness.
• To correlate effective connectivity with objective measures of sleepiness and alertness.

Main Methods:

• Used electroencephalography (EEG) to record responses to Transcranial Magnetic Stimulation (TMS) over the frontal lobe in 23 healthy young men.
• Participants performed a vigilance task during 8 sessions over 29 hours of sustained wakefulness.
• Assessed fronto-parietal effective connectivity using Response Scattering (ReSc), quantifying TMS-evoked EEG response propagation.

Main Results:

• Fronto-parietal ReSc significantly changed over the 29-hour wakefulness period.
• Lower night-time fronto-parietal ReSc was associated with poorer vigilance task performance and increased sleepiness.
• No association between ReSc and vigilance was found during daytime wakefulness; changes in response complexity were not observed.

Conclusions:

• Decreased brain response propagation within the fronto-parietal cortex is linked to vigilance failures during night-time prolonged wakefulness.
• This study reveals a novel neural mechanism underlying the detrimental effects of extended night-time wakefulness on cognitive function.
• Findings highlight the importance of effective connectivity in maintaining vigilance during challenging wakefulness conditions.