## 3 Results  
### Group Differences of Functional Connectivity  
Table 2 reported the driving-related changes in functional connectivity. We found that the connections between the pre-SMA and the left orbital frontal cortex (IOFC), the left superior frontal gyrus (ISFG) and the left middle temporal gyrus (IMTG) were stronger in drivers than in the controls (\(p<0.05\), Topological FDR corrected). On the contrary, the drivers showed weaker functional connectivity (\(p<0.001\), uncorrected) between the pre-SMA and the right middle frontal gyrus (rMFG), and the right inferior parietal lobule (rIPL), while the significance of these two connections did not reach the predefined significance  
level (i.e., \(p<0.05\), Topological FDR corrected). Interestingly, there were no significant SMA proper-related functional connectivity differences between the drivers and controls, suggesting that the driving-related changes in functional connectivity were specific to the pre-SMA and did not extend to the SMA proper.  
Taking the entire SMA as the seed region, the results showed that a functional connectivity difference was only revealed in the ISFG (\(p<0.001\), uncorrected); however, the significance of this connection did not pass the multiple comparison correction (\(p<0.05\), Topological FDR corrected). This finding suggests that the fine segmentation of brain regions can effectively improve the sensitivity of the analysis, ensuring some meaningful results would not be merged by the average effect of rough brain region division.  
To sum up, we found that three brain regions (the ISFG, the IOFC and the IMTG) showed significant group differences of functional connectivity with the pre-SMA (\(p<0.05\), Topological FDR corrected), indicating that the brain network consisted of the above four regions, which highlighted driving-related functional integration features. Figure 2A illustrated the functional connectivity pattern among the four regions, and Figure 2B showed the error bar of each connection for the driver and the control groups.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Anatomical Area**} & \multirow{2}{*}{**Size**} & \multicolumn{4}{c}{**MNI Coordinates**} & \multirow{2}{*}{**T Value**} & \multirow{2}{*}{**\(p\) Value**} & \multirow{2}{*}{**Brodmann’s**} \\  & & & \(\mathbf{x}\) & \(\mathbf{y}\) & \(\mathbf{z}\) & & **(FDR Corrected)** & **Area** \\ \hline
**Pre-SMA** & & & & & & & & \\
**Driver > control** & & & & & & & & \\ Left orbital frontal cortex & \(113\) & \(-21\) & \(57\) & \(-9\) & \(5.62\) & \(0.003\) & \(10,11\) \\ Left superior frontal gyrus & \(63\) & \(-18\) & \(60\) & \(21\) & \(4.52\) & \(0.011\) & \(9,10\) \\ Left middle temporal gyrus & \(51\) & \(-60\) & \(-21\) & \(-9\) & \(4.43\) & \(0.011\) & \(21\) \\
**Driver < control** & & & & & & & \\ Right middle frontal gyrus & \(27\) & \(39\) & \(6\) & \(39\) & \(4.47\) & \(0.189\) & \(6,9\) \\ Right inferior parietal lobule & \(33\) & \(51\) & \(-30\) & \(36\) & \(4.15\) & \(0.138\) & \(2,40\) \\
**SMA proper** & & & & & & & \\ No significance & & & & & & \\
**Whole SMA** & & & & & & & \\
**Driver > control** & & & & & & & \\ Left superior frontal gyrus & \(29\) & \(-21\) & \(57\) & \(21\) & \(4.12\) & \(0.497\) & \(10\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Brain regions exhibit significant functional connectivity differences with sub-regions of the supplementary motor area between the driver and control groups.  
Figure 2: Driving-related changes in functional connectivity. (**A**) Connections between the pre-SMA and the left orbital frontal cortex (IOFC), the left superior frontal gyrus (ISFG) and the left middle temporal gyrus (IMTG) were stronger in drivers than in controls. (**B**) Bar chart plot the mean correlation values of the above connections in the driver and control groups; error bars \(\pm\) SEM (\({}^{*}p<0.05\), Topological FDR corrected; two-sample \(t\)-test).