The human superior colliculus motor region does not respond to finger movements

Electrophysiological studies in macaques and functional neuroimaging in humans revealed a motor region in the superior colliculus (SC) for upper limb reaching movements. Connectivity studies in macaques reported direct connections between this SC motor region and cortical premotor arm, hand, and finger regions. These findings motivated us to investigate if the human SC is also involved in sequential finger tapping movements. We analysed fMRI task data of 130 participants executing simple finger tapping from the Human Connectome Project (HCP). While we found strong signals in the SC for visual cues, we found no signals related to simple finger tapping. Assuming a differential effect owing to simple and complex finger tapping sequences, we searched for responses in the SC corresponding to complex finger tapping above simple finger tapping sequences. We observed expected signal differences in cortical motor and premotor regions, but our analyses provided no evidence for signals related to simple or complex finger tapping in the SC. Despite evidence for direct anatomical connections of the SC motor region and cortical premotor hand and finger areas in macaques, our results suggest that the SC is not involved in simple or complex finger tapping in humans.