Dynamic hippocampal functional connectivity responses to varying working memory loads following total sleep deprivation

Abstract

Sleep loss with work overload can impact human cognitive performance. However, the brain's response to an increased working memory load following total sleep deprivation (TSD) remains unclear. In the present study, we focussed on the dynamic response of the hippocampus to increased working memory load before and after total sleep deprivation of 36 h. A total of 16 male participants completed a verbal working memory task under functional magnetic resonance imaging. After wholebrain activation analysis and region of interest analysis of the hippocampus, the generalised form of context-dependent psychophysiological interactions (gPPI) was used to analyse the hippocampal functional connectivity with the whole brain. The results revealed that as the working memory load increased within a small range, from 0-back to 1-back task, the left hippocampal functional connectivity decreased with the left supplementary motor area, left pars opercularis, left rolandic operculum, right superior frontal gyrus, bilateral precentral gyrus, and left middle cingulate cortex following total sleep deprivation compared with that observed in resting wakefulness.When the working memory load further increased from 1-back to 2-back task, the connectivity increased between the left hippocampus and the left superior parietal lobule as well as between the left hippocampus and right lingual gyrus after total sleep deprivation compared with that observed in resting wakefulness. Moreover, the left hippocampus gPPI effect on the left middle cingulate cortex and left superior parietal lobule could predict the behavioural test accuracy in 1-back and 2-back task, respectively, following total sleep deprivation. These findings indicated that increased working memory load after total sleep deprivation disrupts working memory processes. The brain reacts to these disruptions in a dynamic and flexible manner, involving not only brain activation but also hippocampus-related functional network connections.

Altered Cerebro-Cerebellar Functional Connectivity Associated with Working Memory Decline after Sleep Deprivation

“…Another study demonstrated decreased FC between the left hippocampal and bilateral precentral gyri during the n-back task after acute SD, which implied a role for the precentral gyrus during the WM task [39]. Taken together, these ndings provide evidence for the role of these cerebral regions in cognitive and emotional processing after SD.…”

Altered Postcentral Connectivity after Sleep Deprivation Correlates to Impaired Risk Perception: A Resting-State Functional Magnetic Resonance Imaging Study

“…In addition, 48–72 h of SD is the second trough period, with a 40–50% decline in cognitive function [ 3 ]. Previous studies have shown that SD can strongly impair human cognitive function, including attentional lapses [ 4 ], delayed sensations [ 5 ], impaired working memory [ 6 ], uncontrollable emotions [ 7 ], and confused thinking [ 8 ]. However, few studies have investigated the neural mechanisms underlying advanced cognitive functions, particularly risky decision-making.…”

Cognitive Load Moderates the Effects of Total Sleep Deprivation on Working Memory: Evidence from Event-Related Potentials

“…A study explored the electrophysiological mechanisms of WM alteration after TSD and showed that information replacement in WM was reduced after 36 h of TSD [ 11 ]. Two studies have demonstrated that brain regions associated with memory (e.g., hippocampus) were impaired by TSD [ 12 ], which also led to dysfunctional consolidation and reconsolidation during memorization [ 13 ]. In conclusion, a large number of studies showed that TSD has a negative impact on cognitive function.…”

“…However, the role of load, one of the important factors of WM, in the relationship between TSD and WM and its neurophysiological mechanisms is not yet known. A functional magnetic resonance imaging (fMRI) study explored the brain’s response to increased WM load following TSD, finding that WM was impaired [ 12 ]. As the temporal resolution of EEG is better than that of fMRI, it is more suitable for studying electrophysiological mechanisms.…”