This study examined the effects of an 11-week aerobic exercise intervention on executive function (EF) and white matter integrity (WMI). In total, 28 deaf children (aged 9–13 years) were randomly assigned to either an 11-week exercise intervention or the control group. All the children had behavioral assessment and diffusion tensor imaging prior to and following the exercise intervention. The behavioral performance results demonstrated that EF was enhanced by exercise. Relative to the control group, WMI of the exercise intervention group showed (1) lower fractional anisotropy (FA) in the pontine crossing tract (PCT) and right cingulum (hippocampus) (CH), genu of the corpus callosum (gCC), right inferior cerebellar peduncle (ICP), left superior corona radiata (SCR), and left superior frontooccipital fasciculus (SFOF); (2) higher mean diffusivity (MD) in the gCC, right CH, right inferior frontooccipital fasciculus (IFOF), and left anterior limb of the internal capsule (ALIC); and (3) lower MD in the left ICP and left tapetum (TAP). Furthermore, the lower FA in gCC showed a significant negative correlation with improvement in behavioral performance, but the correlation was not significant after FDR correction. These results suggest that exercise can effectively improve deaf children’s EF and reshape the WMI in deaf children. The improved EF by exercise is not related to a reshaping of WMI, but more studies on the relationship between EF and WMI by exercise may be needed.
Executive function (EF), including inhibition, working memory, and shifting, refers to higher and meta-levels of cognitive processes that regulate and organize purposeful and goal-directed behaviors [
A burgeoning body of literature has emerged on the positive effects of aerobic exercise on the brain and EF. Exercise plays a causal role in improving EF, as exercise training improves performance of EF tasks [
Exercise intervention improved EF and altered brain activation as assessed by functional magnetic resonance imaging (fMRI). Specifically, a 6-month exercise intervention in older adults improved performance and increased prefrontal and posterior parietal activation during a flanker task in the exercise group as compared to the controls [
With evidence that brain activation is affected by exercise, one issue that warranted investigation was whether exercise alters brain structure. Altered white matter structure may be an underlying cause of functional change, given the evidence that interindividual differences in brain activation reflect white matter integrity (WMI) [
WMI has been associated with fitness in several cross-sectional studies. Higher aerobic fitness in adults was associated with higher FA in the cingulum and corpus callosum, possibly relating to motor planning and control [
Given the evidence that exercise improved EF and altered associated brain activation in prior studies, we investigated whether an exercise intervention in deaf children improves WMI. Only deaf children were recruited for the current study; the EF of deaf children is retarded, and they are therefore likely to derive greater benefits from exercise [
The 28 deaf children recruited from two special education schools who participated in the study had normal or corrected-to-normal vision and were right-handed as assessed by the Edinburgh Test [
All participants were then randomly assigned to either the control or the exercise intervention group. The exercise group included six females and eight males. The other six females and eight males constituted the control group. Age and gender were well matched between the two groups. MRI was completed with DTI data available for 28 children at baseline and 20 at posttest. Of the 20 children with both baseline and posttest data, one was excluded due to the loss of behavioral performance data and the other was excluded because behavioral performance was an extreme outlier. Thus, the present study included 18 children: 10 in the exercise group and 8 in the control group (Table
Participants’ demographics and treatment-induced heart rates (
Variables | Control group | Experimental group | |
---|---|---|---|
8 | 10 | — | |
Sex (male/female) | 4/4 | 3/7 | 0.52b |
Age (years) | 11.50 ± 0.76 | 10.20 ± 1.23 | 0.02a |
BMI (height/weight2) | 17.88 ± 1.46 | 17.90 ± 2.42 | 0.98a |
4 | 4 | — | |
Sex (male/female) | 2/2 | 2/2 | — |
HR during treatment | 89.30 ± 10.30 | 136.40 ± 0.57 | 0.03a |
Values are presented as
The aerobic exercise program was adapted from Chen et al. [
A test-tool designed by Chen et al. [
Images were acquired at the Affiliated Hospital of Yangzhou University on a Siemens Magnetom Tim Verio 3 Tesla scanner. During scanning, head position was stabilized with a vacuum pillow and/or foam padding. Diffusion images were acquired using an echo planar imaging sequence (acquisition
Diffusion images were processed using a MATLAB toolbox named “Pipeline for Analyzing braiN Diffusion imAges (PANDA) (
In this longitudinal study, participants were scanned twice with MRI. MRI was performed as follows: a pretest scan performed before exercise intervention (MRI 1) and a posttest scan 11 weeks after completion of the intervention period (MRI 2). The control group, consisting of age- and gender-matched subjects scanned at pretest and posttest, did not participate in any additional aerobic exercise during the 11 weeks (Figure
Experimental process.
All analyses were conducted using SPSS Version 20.0 (IBM, Armonk, N.Y., USA). Demographic variables were compared between the control and exercise groups with independent sample
The participants’ demographic details are presented in Table
The heart rates for the control and exercise groups were 42.52% and 64.95% of the maximal heart rate, respectively [
The groups did not differ significantly at baseline on any of the characteristics listed in Table
Performance for three fundamental aspects of executive function (
Control group | Experimental group | |||
---|---|---|---|---|
Pretest | Posttest | Pretest | Posttest | |
RT (ms) | ||||
Inhibition | 17.80 ± 20.70 | 29.88 ± 21.55 | 38.93 ± 16.97 | 9.80 ± 5.22 |
Working memory | 651.30 ± 104.04 | 622.51 ± 93.36 | 724.09 ± 112.13 | 607.53 ± 71.53 |
Shifting | 277.50 ± 206.72 | 339.87 ± 160.79 | 278.43 ± 50.00 | 225.69 ± 60.81 |
Accuracy (%) | ||||
Inhibition | ||||
Congruent | 88.75 ± 12.08 | 88.13 ± 14.64 | 93.50 ± 6.55 | 95.20 ± 4.13 |
Incongruent | 87.13 ± 11.45 | 87.13 ± 12.40 | 87.40 ± 13.60 | 91.00 ± 7.12 |
Working memory | 64.00 ± 26.79 | 68.00 ± 19.24 | 83.80 ± 20.47 | 90.10 ± 8.48 |
Shifting | ||||
Homogeneous | 80.00 ± 11.46 | 73.34 ± 24.49 | 80.20 ± 15.83 | 84.50 ± 16.22 |
Heterogeneous | 53.25 ± 17.91 | 46.88 ± 20.32 | 48.30 ± 30.39 | 63.30 ± 33.20 |
A repeated measures ANOVA revealed the main effects to be time [
Regarding accuracy, no significant interaction effect was observed in inhibition effect regarding “congruent” [
A repeated measures ANOVA revealed the main effects for time [
Regarding accuracy, no significant interaction effect was observed in working memory [
A repeated measures ANOVA revealed the main effects to be time [
Regarding accuracy, no significant interaction for shifting was observed in “homogeneous” [
There was a significant group-by-time interaction between groups in some WMI measures (Figure
(a) nine anatomical regions defined by the ICBM DTI-81 atlas with significant changes after exercise intervention. Difference in MD (b) and FA (c) values for specific fiber tracts in an atlas-based ROI analysis between the experimental group (blue, orange) and the control group (gray, yellow).
We found a significant negative correlation between WMI and behavioral performance, wherein a decrease in WMI in the gCC (from pretest to posttest) was associated with a lessening in inhibition for deaf children in the exercise intervention group (Flanker task, pretest to posttest) and reaction time (
The current study was designed to explore the effects of aerobic exercise on EF and WMI in deaf children. Children from two similar special education schools were randomly allocated to two groups: an exercise intervention group, receiving an aerobic exercise intervention including running games, jumping rope, and wushu, and a control group that did not attend any additional aerobic exercise. We controlled for all the confounding variables. Consequently, reliable exercise gains emerged, allowing us to observe the neural basis of exercise-improved EF.
A rapidly growing body of literature indicates that, from both behavioral and neuroelectric perspectives, physical exercise improves EF. As observed here, deaf children’s EF performance in the exercise intervention group was better than that in the control group—in agreement with previous studies [
Recently, a number of studies have focused on exploring the effects of exercise on the brain. Some evidence has indicated that exercise intervention can cause microstructural changes in the WM [
Previous research shows that, compared with normal-hearing subjects, the microstructural changes of brain white matter in deaf subjects have lower FA in their bilateral auditory [
Higher MD in deaf children was observed also in the right IFOF. A decreased FA among deaf subjects has been previously reported for the right IFOF [
Lower FA and higher MD occurred in the gCC in our study, suggesting that the lower FA could be attributable to myelination abnormalities. Previous research found that deaf subjects show lower AD in the gCC relative to normal-hearing subjects, which might be related to impaired motor proficiency and balance problems in people with sensorineural hearing loss [
Our results found higher WMI in the left ICP and left TAP after exercising, while WMI was reduced in the PCT, right CH, right ICP, and left SFOF. However, similar results have not been observed in previous relevant studies. It is possible that our results only pertain to our study due to the small sample size of our study. However, even if this is true, our results may provide a basis for future research comprising more test subjects.
The change in diffusion anisotropy of deaf children implies an alteration in WMI, but we cannot draw conclusions from a one-sided index. In our study, we have shown where the changes are, but the interpretation of diffusion indices in deaf children requires further research.
We found a significant correlation in deaf children (following an imposed exercise regimen) between lower WMI in the gCC and better inhibition behavioral performance (declines in reaction time). Nevertheless, perhaps because our sample size was small or our intervention time was short, the correlation was not significant after FDR correction. The existing theory indicates that exercise improves cognitive functioning by improving brain plasticity (structural components, activation patterns, functional connectivity, etc.) [
Our results demonstrated that, after establishing an exercise regimen in deaf children, EF improved in three behavioral performance measures and declined for WMI in the PCT, right CH, left SFOF, right IFOF, right ICP, left SCR, left ALIC, and gCC. In addition, WMI increased in left ICP and left TAP after exercise. In summary, our results suggest that exercise intervention may reshape the microstructure of WM in deaf children, which may have some implications for the instruction of alternative sport programs for children with executive dysfunction.
The authors declare that there is no conflict of interest regarding the publication of this paper.
This research was supported by grants from the National Natural Science Foundation of China (31300863 and 31771243) and the Fok Ying Tong Education Foundation (141113) to Ai-Guo Chen.