Given that dual tasks (e.g. calculation while walking) have been conducted in a number of trials to induce freezing, we asked if the higher PAC during freezing trials could be directly related to dual tasks rather than freezing. We first validated that dual-task trials did have higher freezing severity than no-task trials (P = 0.041 for freezing time proportion, P = 0.009 for freezing frequency, signed-rank test, Fig. 2D). But interestingly, dual-task trials had similar PAC levels to no-task trials (P = 0.278, signed-rank test, Fig. 2E), and dual tasking itself was not correlated with high PAC level (Spearman r = 0.030, P = 0.583). If we controlled the factor of freezing by analysing only the non-freezing trials, we found that dual-task non-freezing trials had even significantly lower PAC than no-task trials (P = 0.006, signed-rank test, Fig. 2F). These results indicated that PAC and dual tasking were not directly associated, but may interact in a more complex way.
