Ageing‐related changes in nap neuroscillatory activity are mediated and moderated by grey matter volume

Abstract

Ageing-related changes in grey matter result in changes in the intensity and topography of sleep neural activity. However, it is unclear whether these findings can be explained by ageing-related differences in sleep pressure or circadian influence. The current study used high-density electroencephalography to assess how grey matter volume differences between young and older adults mediate and moderate neuroscillatory activity differences during a midday nap following a motor sequencing task. Delta, theta, and sigma amplitude were reduced in older relative to young adults, especially over frontocentral scalp, leading to increases in relative delta frontality and relative sigma lateral centroposteriority. Delta reductions in older adults were mediated by grey matter loss in frontal medial cortex, primary motor cortex, thalamus, caudate, putamen, and pallidum, and were moderated by putamen grey matter volume.

Aging-Related Changes in Cortical Sources of Sleep Oscillatory Neural Activity Following Motor Learning Reflect Contributions of Cortical Thickness and Pre-sleep Functional Activity

“…Notably, aging-related reductions in estimated frontal medial cortex delta activity were not mediated by cortical thinning, despite prior evidence that frontal medial cortex gray matter loss (volume and thickness) mediates aging-related reductions in scalp-recorded delta activity (Mander et al, 2013;Latreille et al, 2019;Fitzroy et al, 2021b). This result indicates that the mediating role of frontal medial cortex atrophy in aging-related sleep delta reductions at the scalp is not a result of reduced delta activity in frontal medial cortex with aging.…”

“…Delta, theta, and sigma activity measured at the scalp all decline over the adult lifespan ( Dijk et al, 1989 ; Landolt et al, 1996 ; Carrier et al, 2001 ; Gaudreau et al, 2001 ; Nicolas et al, 2001 ; Crowley et al, 2002 ; Peters et al, 2014 ; Schwarz et al, 2017 ), in a manner that varies topographically across the scalp. Delta declines are broad but largest medial, theta declines are broad but largest medial frontocentral, and sigma declines are focal over only medial frontocentral scalp ( Landolt and Borbély, 2001 ; Münch et al, 2004 ; Robillard et al, 2010 ; Carrier et al, 2011 ; Martin et al, 2013 ; Mander et al, 2014 ; Sprecher et al, 2016 ; Fitzroy et al, 2021b ). These decline patterns lead to aging-related increases in the relative frontality of delta, and in the relative laterality of sigma ( Sprecher et al, 2016 ; Fitzroy et al, 2021b ).…”

“…Delta declines are broad but largest medial, theta declines are broad but largest medial frontocentral, and sigma declines are focal over only medial frontocentral scalp ( Landolt and Borbély, 2001 ; Münch et al, 2004 ; Robillard et al, 2010 ; Carrier et al, 2011 ; Martin et al, 2013 ; Mander et al, 2014 ; Sprecher et al, 2016 ; Fitzroy et al, 2021b ). These decline patterns lead to aging-related increases in the relative frontality of delta, and in the relative laterality of sigma ( Sprecher et al, 2016 ; Fitzroy et al, 2021b ).…”

“…However, aging-related changes in the estimated sources of sleep oscillatory activity have not been previously investigated. Given that aging-related changes in cortical structure ( Mander et al, 2013 ; Dubé et al, 2015 ; Varga et al, 2016 ; Fogel et al, 2017 ; Latreille et al, 2019 ; Fitzroy et al, 2021b ) and brain activation during learning ( Fitzroy et al, 2021a ) are associated with changes in the scalp EEG during sleep, it is likely that these factors contribute to changes in the generators of the underlying activity during sleep.…”

“…The nature of relationships between aging-related changes in cortical structure and changes in the scalp EEG during sleep suggests changes in the underlying source activity with age. Gray matter atrophy mediates aging-related changes in the magnitude and scalp topography of delta and theta activity in a region-specific manner ( Mander et al, 2013 ; Dubé et al, 2015 ; Varga et al, 2016 ; Latreille et al, 2019 ; Fitzroy et al, 2021b ). Gray matter volume also has age-moderated effects on the magnitude and scalp topography of sigma activity in a region-specific manner ( Fogel et al, 2017 ; Fitzroy et al, 2021b ).…”