Postponed Amplification of Default-mode Deactivation in Mental Rotation after 5-day Night Shift
Poster No:
2005
Submission Type:
Abstract Submission
Authors:
Ting-Chun Yao1, Tengmao Yao2, Chih-Mao Huang3, Yi-Ping Chao4, Yu-Tang Tung5, Changwei Wu2
Institutions:
1Taipei Medical University, Taipei, Taiwan, 2Taipei Medical University, New Taipei, Taiwan, 3National Yang Ming Chiao Tung University, Hsinchu, Taiwan, 4Chang Gung University, Taoyuan, Taiwan, 5National Chung Hsing University, Taichung, Taiwan
First Author:
Co-Author(s):
Introduction:
To sustain the workloads in healthcare and industries, many shift workers are required to work in a 24/7 shift pattern. A meta-analysis showed that shift work could lead to decrease in neurobehavioral performances[1] , as well as cognitive impairments and brain-network alterations in shift work disorder [2]. However, current evidence emphasized on behavioral tests or resting-state fMRI, but it remains unclear how brain activities decline with cognitive dysfunctions in shift workers. One possibility is that the induced sleep deprivation might reduce the anti-correlation between dorsal attention network (DAN) and default-mode network (DMN)[3]. Therefore, we investigated the changes in brain activity associated with visuospatial memory in medical shift workers. We expected that in task engagements, DAN activities would be amplified with reduced DMN deactivations after night shift, as compared to the condition before shift.
Methods:
We recruited 9 medical shift workers (age = 26.4 ± 5.0) in the study, and they underwent 3 MRI measures: before the shift (Pre), after a 5-day night shift (Post), and additional 4-day recovery days (Rest). Each fMRI measure was conducted in a 3T Prisma scanner using GE-EPI sequence with voxel size = 3.44×3.44x3.4 mm3; TR/TE= 2000/32 msec, FA= 77°. The mental rotation task was set as block design of 8 blocks in total, where each block contained 8 trials per block (every trial contained 2.5 s stimuli and an interval of 0.5 s), followed by a fixation cross lasting for 24 s. In each trial, one gray graph was shown on the screen as the reference, and the participant was instructed to match the reference graph with one of the two red graphs with mental 2D rotations by button pressing. After data collection, SPM12 was used for typical preprocessing steps on all fMRI data, general linear models for individual and group analysis for the brain activation maps of mental rotation tasks. In the region-of-interest (ROI) analysis, we used MarsBaR to prescribe the brain-activity ROIs from a functional localizer of additional dataset with the same protocol (see another abstract: #1451) or the AAL template. One-way repeated-measure ANOVA and post-hoc tests with FDR correction were used (R Studio) to analyze the brain-activity changes along the 3 time points along the night-shift protocol.
Results:
Deviant away from our expectation, there was no difference in brain activations between Pre and Post, and between Pre and Rest when performing the mental rotation task. Instead, the shifting workers exhibited greater deactivation of DMN regions in Rest as compared with those in Post, including bilateral inferior parietal lobules, left medial prefrontal cortex, and right precuneus. In ROI analysis, we extracted ROI value at bilateral angular gyri (LAG & RAG), right precuneus (RPC), and bilateral medial frontal gyri (LMFG, AAL23; RMFG AAL24). The repeated-measure ANOVA revealed significant differences among the three conditions (LAG: F(2,16) = 6.44, p = 0.009; RAG: F(2,16) = 8.06, p = 0.004; RPC: F(2,16) = 4.69, p = 0.025; RMFG: F(2,16) = 8.06, p = 0.004; LMFG: F(2,16) = 4.64, p = 0.026). However, post hoc analysis only indicated enhanced deactivation in the Rest condition only at LAG (p = 0.021), RAG (p = 0.014), RPC (p = 0.034), and RMFG (p = 0.004) when performing the mental rotation task.
·Figure 1. Regions with greater activation in left inferior parietal lobule (IPL) and RPC and corresponding result of ROI analysis
·Figure 2. Result of whole-brain and ROI analysis in RIPL and medial frontal gyri (only left medial prefrontal cortex is significant in whole-brain analysis, but we conduct ROI analysis on both sides)
Conclusions:
Interestingly, after 5-day night shifts (Post), the DMN regions exhibited less deactivation (get close to zero point) as compared with that in the Pre condition, resembling prior findings [4]. However, after 4-day recovery, these participants showed stronger DMN deactivation while executing tasks, significantly different from the Post condition, implying an overcompensation effect on the DMN deactivation in mental rotation task. However, regions associated with DAN did not show any significant results across conditions, which might be attributed to the limitation of sample size.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI) 2
Perception, Attention and Motor Behavior:
Attention: Visual 1
Keywords:
Cognition
FUNCTIONAL MRI
NORMAL HUMAN
1|2Indicates the priority used for review
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2. Ning, Y., Li, K., Zhang, Y., Chen, P., Yin, D., Zhu, H., & Jia, H. (2020). Assessing Cognitive Abilities of Patients With Shift Work Disorder: Insights From RBANS and Granger Causality Connections Among Resting-State Networks. Frontiers in psychiatry, 11, 780.
3. Dai, C., Zhang, Y., Cai, X., Peng, Z., Zhang, L., Shao, Y., & Wang, C. (2020). Effects of Sleep Deprivation on Working Memory: Change in Functional Connectivity Between the Dorsal Attention, Default Mode, and Fronto-Parietal Networks. Frontiers in human neuroscience, 14, 360.
4. Chee, M. W., & Chuah, Y. M. (2007). Functional neuroimaging and behavioral correlates of capacity decline in visual short-term memory after sleep deprivation. Proceedings of the National Academy of Sciences of the United States of America, 104(22), 9487–9492.