PT  - JOURNAL ARTICLE
AU  - Laurentius Huber
AU  - Emily S. Finn
AU  - Daniel A. Handwerker
AU  - Marlene Bönstrup
AU  - Daniel Glen
AU  - Sriranga Kashyap
AU  - Dimo Ivanov
AU  - Natalia Petridou
AU  - Sean Marrett
AU  - Jozien Goense
AU  - Benedikt A. Poser
AU  - Peter A. Bandettini
TI  - Sub-millimeter fMRI reveals multiple topographical digit representations that form action maps in human motor cortex
AID  - 10.1101/457002
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 457002
4099  - http://biorxiv.org/content/early/2019/02/25/457002.short
4100  - http://biorxiv.org/content/early/2019/02/25/457002.full
AB  - The human brain coordinates a wide variety of motor activities. On a large scale, the cortical motor system is topographically organized such that neighboring body parts are represented by neighboring brain areas. This homunculus-like somatotopic organization along the central sulcus has been observed using neuroimaging for large body parts such as the face, hands and feet. However, on a finer scale, invasive electrical stimulation studies show deviations from this somatotopic organization that suggest an organizing principle based on motor actions rather than body part moved. It has not been clear how the action-map organization principle of the motor cortex in the mesoscopic (sub-millimeter) regime integrates into a body map organization principle on a macroscopic scale (cm). Here we developed and applied advanced mesoscopic (sub-millimeter) fMRI and analysis methodology to non-invasively investigate the functional organization topography across columnar and laminar structures in humans. We find that individual fingers have multiple mirrored representations in the primary motor cortex depending on the movements they are involved in. We find that individual digits have cortical representations up to 3 mm apart from each other arranged in a column-like fashion. These representations are differentially engaged depending on whether the digits’ muscles are used for different motor actions such as flexion movements like grasping a ball or retraction movements like releasing a ball. This research provides a starting point for noninvasive investigation of mesoscale topography across layers and columns of the human cortex and bridges the gap between invasive electrophysiological investigations and large coverage non-invasive neuroimaging.