The Effects of Obstacle Size and Timing on Prefrontal Cortex Activation in Patients with Parkinson's Disease

I Maidan, T Sharon, I Kurz, H Bernad-Elazari, S Shustak, I Galperin, N Giladi, A Mirelman, J Hausdorff

Research output: Contribution to journalMeeting Abstractpeer-review


Objective: To evaluate the effects of obstacle height and anticipation time on prefrontal cortex (PFC) activation in patients with Parkinson’s disease (PD) and older adults.

Background: Tripping over an obstacle is one of the most common causes of falls among patients with PD. Recent studies suggest that PFC plays an important role during usual walking and obstacle negotiation in PD patients. However, the effects of obstacle type on PFC have not been systematically evaluated.

Method: 26 older adults (age:71.3±8.9 years; 11 women) and 34 patients with PD (age:67.4±5.7 years; 14 women, disease duration:5.8±4.5 years) walked in an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 50mm and 100mm. PFC activation was measured using a functional near-infrared spectroscopy (fNIRS) system while Kinect cameras evaluated performance. PFC activation was defined based on mean HbO2 at 3 seconds before, during, and after obstacle. Changes between types of obstacles and groups were assessed using linear-mixed models. Pearson correlations evaluated the relationship between PFC and performance.

Results: Compared to quiet standing, PFC activation increased before, during (further) and after (to the highest level) obstacle negotiation (p<0.001). PFC activation was higher in patients than in older adults in both anticipated and unanticipated obstacles (p=0.007). There was a significant group X time (before/during/after) interaction effect and a significant group X condition (anticipated/unanticipated) interaction effect, with larger effects seen in the patients. Increased PFC activation during anticipated obstacles was correlated with greater distance of the leading foot after the obstacles only in patients (r=0.409, p=0.020).

Conclusion: These findings provide direct evidence of the role of the PFC during obstacle negotiation in PD patients. The higher activation in PD patients during both anticipated and unanticipated obstacles may indicate that the prefrontal response is not specific and does not necessarily relate to the time course of motor planning. However, the correlation with foot clearance points to the effectiveness of this compensatory mechanism. With PD, a larger increase in HbO2 during complex situations may further limit activation, providing a potential explanation of the high risk of falls in PD.
Original languageEnglish
JournalMovement Disorders
StatePublished - 2019


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