The Influence of M1 and DLPFC iTBS on BCI Performance: A TMS and fNIRS Study

Brain-computer interface (BCI) control inefficiency often occurs in stroke survivors due to insufficient sensorimotor activity generated during motor imagery. Previous studies focused on upregulating excitability of primary motor cortex (M1) alone. Dorsolateral prefrontal cortex (DLPFC), an important region for motor imagery, may be effective for improving BCI performance. This study is aimed at investigating how intermittent theta burst stimulation (iTBS) targeted on M1 and DLPFC influences BCI performance and its neural mechanisms.25 healthy subjects (9 males) received four types of iTBS (i.e., M1 iTBS, DLPFC iTBS, combination of M1 and DLPFC iTBS and sham iTBS) on separate days. BCI control testing, functional near-infrared spectroscopy assessment and single-pulse transcranial magnetic stimulation were performed before and immediately after iTBS in each session. Corticospinal excitability, brain activation, and functional connectivity were calculated. Our results revealed that corticospinal excitability was significantly increased after M1 iTBS (P = 0.016), with the magnitude of increase positively correlated with BCI performance (P = 0.013). Frontoparietal network functional connectivity was significantly increased after DLPFC iTBS (P's<0.05), with the magnitude of increase positively correlated with changes in BCI performance (P's<0.05). In conclusion, M1 iTBS and DLPFC iTBS alone influences BCI performance through specific neural mechanisms, and the combination of M1 and DLPFC iTBS did not induce any significant results. M1 iTBS could influence BCI performance by enhancing corticospinal excitability, while DLPFC iTBS could influence BCI performance by increasing frontoparietal network connectivity. These findings could contribute to the advancement of novel therapeutic strategies aimed at enhancing BCI effectiveness for neurological populations. Trial registration: The study was retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR2500097678). Registration Date: 2025-02-24.