A new MRI subject position to explore simultaneous BOLD oscillations of the brain and the body.

Background: Anatomically and physiologically, there is strong relationship between the brain and body. A new MRI platform covering both the brain and the limb would be beneficial for a more thorough understanding of the brain-body interactions.

New Method: A new arm-over-head (AOH) position was developed to collect MRI of the brain and one arm simultaneously. Subject's tolerability and SNR of both the brain and limb under a serial of seven different TR (250-3000 ms) were tested. Then, blocked motor imagery tasks were performed to test the possible brain-body oscillations.

Results: The new MRI position provided structural images with good quality, and the AOH position had the best SNR under TR 3000 ms (p = 0.03 for the brain; p = 0.064 for the limb). Then, by using both hypothesis-free independent component analysis (ICA) and a priori seed-based functional connectivity (FC) analysis, it is demonstrated during motionless motor imagery tasks there existed possible brain-body BOLD oscillations connecting especially arm flexors to default mode, vision, and sensorimotor networks. The FC appeared at network density as low as 5%.

Comparison With Existing Methods: We have developed a new MRI subject position to explore the possibilities of more extensive neuronal and physiological networks.

Conclusions: The results of this preliminary experiment indicate that functional brain networks might extend outside the brain. A bottom-up circulatory effect might explain this phenomenon. Nonetheless, considering the mechanism of neural top-down control and the nature of complex brain networks, the existence of a more extensive whole-body functional network is rational and possible.