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

Abstract

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. 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. 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. This study confirms that care should be taken when drawing conclusions about neuronal activity from the BOLD signal, particularly for the cerebellum.