Author(s): PESKAR, M., GRAMANN, K., KALC, M., MILADINOVIC, A., MANGANOTTI, P., MARUŠIC, U., Institution: SCIENCE AND RESEARCH CENTRE KOPER, Country: SLOVENIA, Abstract-ID: 2516

Although highly automated, human gait is dependent on cortical resources and can be observed in spectral features such as sustained beta band (18-30Hz) desynchronization and gait-phase dependent modulation in the low gamma-band (24–40 Hz) recorded over central sensorimotor cortices. Contrary, Parkinson’s disease (PD) is characterized by beta-band hypersynchrony which is positively associated with the symptoms of bradykinesia. However, this cortical phenomenon has never been noninvasively investigated in ecologically valid conditions during unrestricted overground walking and concurrent performance of a cognitive task. This study aimed to elucidate the mechanisms subserving full-body movement execution in conditions where attentional resources are simultaneously allocated to both cognitive and motor tasks mimicking real-life scenarios in PD patients. Sixteen early on-medication PD patients (aged M = 62.75 ± 5.9 years; 8 women) and 16 healthy controls (HC; aged M = 64.1 ± 6.5 years; 8 women) performed a self-paced overground walking task in a wide (80 cm) and narrow (40 cm) lanes both as single-task conditions (STwide, STnarrow) and with a secondary visual discrimination task as dual-task conditions (DTwide, DTnarrow). A mobile 128-channel EEG and full-body kinematics were recorded to compute gait-phase-dependent spectral modulation at the Cz electrode. Nonparametric cluster-based permutation testing correcting for multiple comparisons across all time-frequency space was used (1000 iteration, α≤.05). We observed faster walking speed for HC versus PD patients (F(1, 30)=8.10, p=.008) and for ST as opposed to DT conditions (F(1, 30)=41.61, p<.001). No significantly different clusters of cortical signatures would discriminate PD patients and HC or wide and narrow lane walking conditions. However, PD patients demonstrated greater synchronization in the beta and low gamma activity in both DT conditions compared to their respective ST variants. The differences were observed in the phase of gait following the heel strikes indicating preparation for shifting the weight to a single leg. The effect was more pronounced in the narrow walk conditions. The PD patients exhibit similar cortical signatures to HC during overground walking but seem to become prone to the cortical signature related to movement inefficiency upon performing cognitive-motor dual-tasking. In PD patients but not HC a secondary cognitive task evoked a gait-phase-locked synchronization in the high spectral frequencies, which could suggest the limited availability of cognitive resources at that particular time during the gait phase while the attention had to be continuously divided between the two tasks. These results indicate that movement execution in PD could be impeded by increasing the load on the cognitive systems. These outcomes provide valuable insights into mechanisms of simple real-life cognitive-motor dual-tasking in PD and can inform intervention and fall prevention strategies.