*3.3. fMRI Brain Imaging Results*

Compared with HCs, mTBI patients showed significantly reduced activation in widespread frontal regions across OG conditions (Table S1), which were mainly distributed in the medial superior frontal gyrus (mSFG), dorsolateral superior frontal gyrus (dlSFG), medial orbital gyrus (mOG), ventrolateral middle frontal gyrus (vlMFG) and rostrodorsal supramarginal gyrus (rdSG).

During the DI condition, mTBI patients exhibited significantly reduced activation in a broad cingulate-frontal network compared to HCs (Table S2), which included the posterior cingulate cortex (PCC), posterior insula (pIns) and other frontal regions.

In addition, for the TS condition, the mTBI patients showed significantly reduced activation in the dorsal caudate (dCau), anterior cingulate cortex (ACC), and other frontal regions (Figure 3, Table 2) compared with HCs.

**Figure 2.** Behavioral results of fMRI task performance. (**A**) Mean response time (RT) during three conditions [ongoing (OG) condition, distractor inhibition (DI) condition, task switch (TS) condition] in mTBI patients and HCs; (**B**) Error rate (ER) during three conditions in mTBI patients and HCs. Error bars represent standard deviation. \*: *p* < 0.05; \*\*: *p* < 0.01. mTBI, mild traumatic brain injury; HCs, healthy controls.

**Figure 3.** Brain activation results from the BOLD-fMRI analysis of the contrast mTBI < HC in task switching (TS) condition (FEW corrected). Compared with HCs, mTBI patients showed significantly reduced activation in the dorsal caudate (dCau), anterior cingulate cortex (ACC), medial superior frontal gyrus (mSFG), dorsolateral superior frontal gyrus (dlSFG).


**Table 2.** Results from the BOLD-fMRI analysis of the contrast mTBI < HCs in TS condition (FWE corrected).

mTBI, mild traumatic brain injury; HCs, healthy controls; FWE, family wise error; TS, task switching; MNI, Montreal Neurological Institute; L, left; R, right; dCau, dorsal caudate; dlSFG, dorsolateral Superior Frontal Gyrus; mSFG, medial Superior Frontal Gyrus; IFG, inferior frontal gyrus; ACC, anterior cingulate cortex.

*3.4. Relationship between Abnormal Activation, Behavioral and Neuropsychological Measures in mTBI*

The reduced dCau activation of the TS condition in mTBI patients was positively correlated with information processing speed (indexed by DSC) (*p* < 0.001, FDR corrected), but negatively correlated with RT for TS condition (*p* < 0.001, FDR corrected). In addition, the RT for TS condition was negatively correlated with information processing speed in mTBI patients (*p* < 0.001, FDR corrected).
