Abnormal patterns of theta frequency oscillations during the temporal evolution of freezing of gait in Parkinson’s disease

OBJECTIVE We sought to characterize the electrophysiological signature of Freezing of gait in Parkinson's disease. METHODS We examined 24 patients with idiopathic Parkinson's disease and significant freezing of gait as they performed a series of timed up-and-go tasks in their 'off' state while electroencephalographic data was collected from four scalp leads. Fast Fourier Transformation was utilized to explore the power spectral density between periods of normal walking and periods of freezing, as well as during the transition between the two states. In addition, Cross Spectrum and Cross Frequency analyses were used to explore the role of impaired temporal and spatial connectivity. RESULTS When compared to walking, episodes of freezing were associated with a significant increase in theta band power within the central and frontal leads. The transition from normal walking to freezing of gait was also associated with increased theta frequency coupling between the central and frontal leads, along with an increase in cross-frequency coupling in the central lead. CONCLUSIONS Episodes of freezing of gait in Parkinson's disease are associated with abnormal oscillatory activity in the brain. SIGNIFICANCE These results provide novel insights into the pattern of spatiotemporal dynamics underlying freezing of gait and may provide a potential means for therapeutic prediction and alleviation of freezing episodes in susceptible patients.