of time.63 The latest Summit RC + S (Medtronic) study64 employed a feedback time scale of 2–10 min in chronic at-home recordings. Longer data segment increases the signal-to-noise ratio helping better differentiate pathological from the physiological state, which may also be applied to PAC indices (e.g. PAC computed in 30 s window is approximately three times the PAC computed in 10 s window, Supplementary Fig. 1). Overall, this study provides a neurophysiology approach to quantify the severity of motor abnormality in FOG. But notably, PAC in M1 cannot model the dynamic change of cognitive burden, which also plays a vital role in the occurrence of FOG. In fact, as per our model, it is the dynamic fluctuation, but not baseline occupation decides the exact time point freezing occurs when keeping bandwidth limit constant. Therefore, future studies tracking changes in the cognitive/limbic circuit during freezing, e.g. through recording heart rate change,65 or neural activities from the prefrontal cortex,34 would immensely enrich the proposed model.
