Cortical layer-dependent response changes in M1 in Parkinson's Disease: a submillimeter 7T fMRI study with 3D passband balanced SSFP

Motivation: How Parkinson's disease (PD) affects the neural circuitry in the primary motor cortex (M1). Goal(s): Investigate laminar response changes in the M1 at early and advanced stages of PD. Approach: A 3D passband bSSFP sequence at 7 Tesla was used to investigate layer-specific functional activity in the M1 of two PD patients during a hand grasping task. Results: Compared to the less affected hand, the more affected hand movement of the early-stage patient showed stronger activation in the superficial layers of M1 in the contralateral hemisphere; while the advanced-stage patient showed overall weaker activations. Impact: These findings provide clues to to dysfunctions and progression of PD in the M1 microcircuitry, showscasing that laminar fMRI is a valuable tool for investigating the mechanisms underlying neurodegenerative disorders.