This study aims to explore the changes in functional connectivity of brain regions in PD with gait disturbance during walking tasks of different difficulties comparing with healthy controls.
We recruited 43 subjects, including 20 PD with gait disturbance(PD)and 23 age-matched healthy controls(HC). All subjects performed simple and dual walking tasks for three times, while wearing a fNIRS hat. All PD subjects were tested during their “OFF” and “ON” medication states (PD-OFF, PD-ON). The brain regions of interests (ROIs)for fNIRS test include Supplementary Motor Area/Premotor Cortex(SMA/PMC)、Primary Motor Area(M1)、Somatosensory association Cortex(SAC)、Primary Somatosensory Cortex(S1)、Prefrontal Cortex(PFC) and Frontal Eye Fields(FEF). The cortical activation was quantified by change in Oxygenated hemoglobin concentration (ΔHBO2) measured by the fNIRS. Functional connectivity between ROIs was estimated by calculating the correlation of cortical activation between ROIs.
Z statistics of z-scored connectivity between ROIs were used to determine task (simple walking task, dual walking task) and group (PD-OFF, PD-ON, HC) effects on functional connectivity.
There was no significant difference between two subject groups in demographic characteristics.
Compared to simple-task, dual-task triggered stronger functional connections between S1 and SAC, PFC, and FEF in the HC group; elicited stronger connections between SMA/PMC and M1 with PFC and FEF, but a weakened SAC-PFC connection in PD-OFF group; activated no additional connections in PD-ON group.
Compared to HC, PD-ON demonstrated weaker SAC-SMA/PMC connection, but stronger S1-M1 and S1-SAC connections during simple-task. During dual-task, however, there were no significant differences in connectivity for PD-ON compared to HC. On the other hand, PD-OFF showed weaker SAC-SMA/PMC connectivity during simple-task, but during dual-task, there was stronger connectivity between FEF and both SMA/PMC and PFC. Additionally, when compared to PD-OFF, PD-ON exhibited stronger PFC-M1 and PFC-SAC connections during simple-task, with no notable differences during dual-task.
Patients with PD and gait disturbances retain the ability to partially strengthen their functional connectivity. However, the compensatory increase in functional connectivity of brain regions in patients with PD is insufficient to complete activities of higher difficulty.
Our findings suggest that the SMA/PMC is a crucial region with weak functional connectivity in PD patients with gait disturbance, but shows limited responsiveness to PD medication. Therefore, it may represent a highly promising target for neural modulation therapy.
Gait disturbance
functional connectivity
