Attention Performance Correlated With White Matter Structural Brain Networks in Shift Work Disorder

A latent profile analysis of shift work tolerance among Chinese male sailors during a prolonged non-24-h rotating shift schedule at sea

Shift work tolerance (SWT) refers to the ability to adapt to shift work without significant adverse consequences. The present study aimed to examine the individual differences in SWT and their predictors and outcomes. Latent profile analyses were conducted using cross-sectional data collected form 448 Chinese male sailors who experienced a prolonged (>30 d) non-24-h rotating shift schedule at sea. Depression, anxiety, sleep disturbance, fatigue, domestic disruption, job satisfaction, work engagement, digestive and cardiovascular symptoms were included as indicators of SWT. The results showed that there existed 2 latent profiles of SWT named as High SWT group and Low SWT group. High SWT group was characterized by low levels on all negative bio-psycho-social outcomes but high levels of work engagement and job satisfaction, while Low SWT group exhibited completely opposite characteristics compared to High SWT group. The level of hardiness could predict profile membership that those with higher level of hardiness were more likely to belong to High SWT group. However, there were no significant differences observed in job performance between two groups. In conclusion, hardiness can serve as a predictor of personnel selection for shift work and hardiness-based intervention programs should be encouraged among the shift workers.

Altered Functional Connectivity of the Thalamus Subregions Associated with Impaired Attention After Sleep Deprivation

Objective

The thalamus plays a critical role in attentional maintenance. Previous studies have revealed the dysfunction of the thalamus in attention decline after acute sleep deprivation (SD). However, the functional connectivity (FC) between the thalamus subregions and cortical regions underlying attentional impairment after acute SD remains unclear. Here, we aimed to probe the relationship between attentional function and the altered thalamocortical FC after acute SD.

Methods

In this study, 25 healthy participants with regular sleep conducted an attentional network test and received a resting-state fMRI scan before and after 24 hours of SD. Then, we analyzed the FC between the thalamus and cerebrum and relationships with attentional function in the enrolled subjects.

Results

Our results showed that the participants showed a significantly lower alerting effect, a higher executive effect, and lower accuracy after acute SD. Compared to the rested wakefulness state, we observed decreased FCs between the "somatosensory" thalamic seed and left frontal pole, right frontal pole, left middle temporal gyrus (posterior division), and right middle temporal gyrus (posterior division). Furthermore, the reduced FC between the right middle temporal gyrus and "somatosensory" thalamic seed was negatively associated with the change in orienting effect of the participants.

Conclusion

Our findings reveal that the disrupted FC between thalamus subregions and cortical regions may contribute to impaired attention after SD.

Comparison of local activation, functional connectivity, and structural connectivity in the N-back task

The N-back task is widely used to investigate working memory. Previous functional magnetic resonance imaging (fMRI) studies have shown that local brain activation depends on the difficulty of the N-back task. Recently, changes in functional connectivity and local activation during a task, such as a single-hand movement task, have been reported to give the distinct information. However, previous studies have not investigated functional connectivity changes in the entire brain during N-back tasks. In this study, we compared alterations in functional connectivity and local activation related to the difficulty of the N-back task. Because structural connectivity has been reported to be associated with local activation, we also investigated the relationship between structural connectivity and accuracy in a N-back task using diffusion tensor imaging (DTI). Changes in functional connectivity depend on the difficulty of the N-back task in a manner different from local activation, and the 2-back task is the best method for investigating working memory. This indicates that local activation and functional connectivity reflect different neuronal events during the N-back task. The top 10 structural connectivities associated with accuracy in the 2-back task were locally activated during the 2-back task. Therefore, structural connectivity as well as fMRI will be useful for predicting the accuracy of the 2-back task.

Altered Functional Connectivity and Topological Organization of Brain Networks Correlate to Cognitive Impairments After Sleep Deprivation

Introduction

Sleep deprivation (SD) has a detrimental effect on cognitive functions. Numerous studies have indicated the mechanisms underlying cognitive impairments after SD in brain networks. However, the findings based on the functional connectivity (FC) and topological architecture of brain networks are inconsistent.

Methods

In this study, we recruited 30 healthy participants with regular sleep (aged 25.20 ± 2.20 years). All participants performed the repeatable battery for the assessment of neuropsychological status and resting-state fMRI scans twice, during the rested wakefulness (RW) state and after 24 h of total SD. Using the Dosenbach atlas, both large-scale FC and topological features of brain networks (ie nodal, global and local efficiency) were calculated for the RW and SD states. Furthermore, the correlation analysis was conducted to explore the relationship between the changes in FC and topological features of brain networks and cognitive performances.

Results

Compared to the RW state, the large-scale brain network results showed decreased between-network FC in somatomotor network (SMN)-default mode network (DMN), SMN-frontoparietal network (FPN), and SMN-ventral attention network (VAN), and increased between-network FC in the dorsal attention network (DAN)-VAN, DAN-SMN after SD. The clustering coefficient, characteristic path length and local efficiency decreased after SD. Moreover, the decreased attention score positively correlated with the decreased topological measures and negatively correlated with the FC of DAN-SMN.

Conclusion

Our results suggested that the increased FC of DAN-SMN and decreased topological features of brain networks may act as neural indicators for the decrease in attention after SD.

Clinical Trial Registration

The study was registered at the Chinese Clinical Trial Registry, registration ID: ChiCTR2000039858, China.