Recent research has identified abnormal beta-gamma phase-amplitude coupling (PAC) in the M1 as a cortical biomarker of parkinsonian motor impairment that can be reversed through therapeutic DBS.15 PAC has been hypothesized as a physiological mechanism for neural intra- and inter-region communication by coordinating the timing of spiking and synaptic inputs,16 while excessive PAC may constrain information transmission.17 Since FOG also involves dysfunction in M1, and is characterized as a disorder associated with impaired neural transmission efficiency in the locomotion system,18 we hypothesized that PAC in M1 might reveal unique information on mechanisms underlying the emergence and treatment of FOG in Parkinson’s disease.
