Whole brain measurements of the positive BOLD response variability during a finger tapping task at 7 T show regional differences in its profiles

PURPOSE: The positive BOLD response can vary across brain regions. Here, the positive BOLD responses of motor regions, including the cerebellum, were investigated by fast fMRI acquisition. METHODS: The participants were asked to perform an event-related finger-tapping task in a 7T MRI scanner during a fast 3D-EPI controlled aliasing in parallel imaging acquisition protocol (CAIPI; TR = 399 ms). The positive BOLD responses of 6 motor regions were extracted and their timings and shapes measured. RESULTS: Compared with other brain regions, the positive BOLD responses in the cerebellum and secondary somatosensory cortex showed delayed onsets, but no differences were observed for the time to-peak. Additionally, variations of the undershoot and main peak amplitudes were also observed, and undershoot was quasi-absent in the cerebellum. CONCLUSION: This study confirms that care should be taken when drawing conclusions about neuronal activity from the BOLD signal, particularly for the cerebellum