Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.

<h4>Objective</h4>Increased levels of reaction time variability (RTV) are characteristics of sustained attention deficits. The clinical significance of RTV has been widely recognized. However, the reliability of RTV measurements has not been widely studied. The present study aimed to ass...

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Main Authors: Zan-Zan Liu, Hui-Jie Qu, Zhuo-Ling Tian, Meng-Jian Han, Yi Fan, Lie-Zhong Ge, Yu-Feng Zang, Hang Zhang
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2017-01-01
Series:PLoS ONE
Online Access:https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0184476&type=printable
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author Zan-Zan Liu
Hui-Jie Qu
Zhuo-Ling Tian
Meng-Jian Han
Yi Fan
Lie-Zhong Ge
Yu-Feng Zang
Hang Zhang
author_facet Zan-Zan Liu
Hui-Jie Qu
Zhuo-Ling Tian
Meng-Jian Han
Yi Fan
Lie-Zhong Ge
Yu-Feng Zang
Hang Zhang
author_sort Zan-Zan Liu
collection DOAJ
description <h4>Objective</h4>Increased levels of reaction time variability (RTV) are characteristics of sustained attention deficits. The clinical significance of RTV has been widely recognized. However, the reliability of RTV measurements has not been widely studied. The present study aimed to assess the test-retest reliability of RTV conventional measurements, e.g., the standard deviation (SD), the coefficient of variation (CV), and a new measurement called the amplitude of low frequency fluctuation (ALFF) of RT. In addition, we aimed to assess differences and similarities of these measurements between different tasks.<h4>Method</h4>Thirty-seven healthy college students participated in 2 tasks, i.e., an Eriksen flanker task (EFT) and a simple reaction task (SRT), twice over a mean interval of 56 days. Conventional measurements of RTV including RT-SD and RT-CV were assessed first. Then the RT time series were converted into frequency domains, and RT-ALFF was further calculated for the whole frequency band (0.0023-0.167 Hz) and for a few sub-frequency bands including Slow-6 (<0.01 Hz), Slow-5 (0.01-0.027 Hz), Slow-4 (0.027-0.073 Hz), and Slow-3 (0.073-0.167 Hz). The test-retest reliability of these measurements was evaluated through intra-class correlation (ICC) tests. Differences and correlations between each EFT and SRT measurement were further examined during both visits.<h4>Results</h4>1) The RT-ALFF of the Slow-5/4/3 and conventional measurements of RT-SD and RT-CV showed moderate to high levels of test-retest reliability. EFT RT-ALFF patterns generated slightly higher ICC values than SRT values in higher frequency bands (Slow-3), but SRT RT-ALFF values showed slightly higher ICC values than EFT values in lower frequency bands (Slow-5 and Slow-4). 2) RT-ALFF magnitudes in each sub-frequency band were greater for the SRT than those for the EFT. 3) The RT-ALFF in the Slow-4 of the EFT was found to be correlated with the RT-ALFF in the Slow-5 of the SRT for both two visits, but no consistently significant correlation was found between the same frequency bands.<h4>Conclusions</h4>These findings reveal good test-retest reliability for conventional measurements and for the RT-ALFF of RTV. The RT-ALFF presented frequency-dependent similarities across tasks. All of our results reveal the presence of different frequency structures between the two tasks, and thus the frequency-dependent characteristics of different tasks deserve more attention in future studies.
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spelling doaj-art-e7d61d2de51c4d3893937a3c0c6bcdbe2025-08-20T03:04:57ZengPublic Library of Science (PLoS)PLoS ONE1932-62032017-01-01129e018447610.1371/journal.pone.0184476Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.Zan-Zan LiuHui-Jie QuZhuo-Ling TianMeng-Jian HanYi FanLie-Zhong GeYu-Feng ZangHang Zhang<h4>Objective</h4>Increased levels of reaction time variability (RTV) are characteristics of sustained attention deficits. The clinical significance of RTV has been widely recognized. However, the reliability of RTV measurements has not been widely studied. The present study aimed to assess the test-retest reliability of RTV conventional measurements, e.g., the standard deviation (SD), the coefficient of variation (CV), and a new measurement called the amplitude of low frequency fluctuation (ALFF) of RT. In addition, we aimed to assess differences and similarities of these measurements between different tasks.<h4>Method</h4>Thirty-seven healthy college students participated in 2 tasks, i.e., an Eriksen flanker task (EFT) and a simple reaction task (SRT), twice over a mean interval of 56 days. Conventional measurements of RTV including RT-SD and RT-CV were assessed first. Then the RT time series were converted into frequency domains, and RT-ALFF was further calculated for the whole frequency band (0.0023-0.167 Hz) and for a few sub-frequency bands including Slow-6 (<0.01 Hz), Slow-5 (0.01-0.027 Hz), Slow-4 (0.027-0.073 Hz), and Slow-3 (0.073-0.167 Hz). The test-retest reliability of these measurements was evaluated through intra-class correlation (ICC) tests. Differences and correlations between each EFT and SRT measurement were further examined during both visits.<h4>Results</h4>1) The RT-ALFF of the Slow-5/4/3 and conventional measurements of RT-SD and RT-CV showed moderate to high levels of test-retest reliability. EFT RT-ALFF patterns generated slightly higher ICC values than SRT values in higher frequency bands (Slow-3), but SRT RT-ALFF values showed slightly higher ICC values than EFT values in lower frequency bands (Slow-5 and Slow-4). 2) RT-ALFF magnitudes in each sub-frequency band were greater for the SRT than those for the EFT. 3) The RT-ALFF in the Slow-4 of the EFT was found to be correlated with the RT-ALFF in the Slow-5 of the SRT for both two visits, but no consistently significant correlation was found between the same frequency bands.<h4>Conclusions</h4>These findings reveal good test-retest reliability for conventional measurements and for the RT-ALFF of RTV. The RT-ALFF presented frequency-dependent similarities across tasks. All of our results reveal the presence of different frequency structures between the two tasks, and thus the frequency-dependent characteristics of different tasks deserve more attention in future studies.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0184476&type=printable
spellingShingle Zan-Zan Liu
Hui-Jie Qu
Zhuo-Ling Tian
Meng-Jian Han
Yi Fan
Lie-Zhong Ge
Yu-Feng Zang
Hang Zhang
Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
PLoS ONE
title Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
title_full Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
title_fullStr Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
title_full_unstemmed Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
title_short Reproducibility of frequency-dependent low frequency fluctuations in reaction time over time and across tasks.
title_sort reproducibility of frequency dependent low frequency fluctuations in reaction time over time and across tasks
url https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0184476&type=printable
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