Study on the effects and mechanisms of rhythmic auditory stimulation on freezing of gait in Parkinson's disease: investigation based on functional near-infrared spectroscopy (fNIRS) technology.

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IntroductionFreezing of gait (FOG) in Parkinson's disease (PD) patients is a critical determinant of motor impairment and fall risk. Rhythmic auditory stimulation (RAS) has been shown to ameliorate FOG symptoms, although the underlying neurophysiological mechanisms are not fully understood.ObjectivesThis research employed functional near-infrared spectroscopy (fNIRS) to analyze three RAS-two external auditory cueing strategies (beat perception and music therapy) and one internal cueing method (mental beat imagery)-to examine gait parameters and cortical activation patterns in Parkinson's disease patients with freezing of gait (PD + FOG) compared to healthy controls (HC). The study also sought to evaluate the therapeutic effectiveness of these rhythm-based interventions in alleviating FOG episodes.MethodsTwenty-eight patients with PD + FOG and twenty-eight age-matched HC were enrolled in the study. Gait analysis was performed during narrow corridor ambulation, designed to induce freezing episodes, and during straight-line walking in an open environment. fNIRS was employed to measure fluctuations in oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HHb) concentrations, serving as indicators of cortical activation. Regions of interest (ROIs) included the prefrontal cortex (PFC), premotor cortex (PMC), and temporal cortex (TLC). Intracortical functional connectivity during each locomotor task was evaluated through correlation analyses of HbO2 signals between the ROIs.ResultsPD + FOG patients exhibited gait disturbances characterized by reduced gait velocity and stride length, along with increased mediolateral postural sway during freezing episodes. Neuroimaging indicated significantly decreased activation in the primary somatosensory cortex (S1), PMC, and PFC compared to healthy controls, despite elevated intracortical connectivity involving indirect corticospinal pathways. Differential responses to RAS interventions were noted: rhythmic auditory cues enhanced connectivity between TLC and PMC; music therapy significantly improved PFC intrinsic connectivity; whereas imagined auditory cues potentially impaired sensorimotor integration due to excessive reliance on internal cognitive mechanisms.ConclusionVarious RAS pathways can ameliorate freezing of gait symptoms by selectively modulating functional connectivity between the prefrontal cortex and sensorimotor circuits. The underlying neural mechanisms may largely involve neural entrainment and reorganization of brain networks. These results offer vital empirical insights into the pathophysiology of gait freezing and provide a preliminary theoretical basis for designing precision neuromodulation interventions.

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