Fig 1.
Experimental conditions are illustrated by symbols: visual input (eyes open/closed), gaze position (straight ahead, eccentric target positions), graviceptive (head down, erect, head up) and proprioceptive (platform vs. foam) input and, finally, different demands on postural control (parallel vs. tandem stance).
Fig 2.
Postural sway as a function of target visibility.
Original recordings of postural medio-lateral (ML, purple) and anterior-posterior (AP, green) center of displacement (CoP in mm) of a healthy control subject (upper trace) and a DBN patient (lower trace) on solid platform with eyes open (A) and closed (B). Group means ± standard error (SEM) are shown in (C) indicating significant larger PSS in patients but an indistinguishable increase of PSS in both groups on eye closure. Accordingly, Romberg’s ratio (D) is not different between groups.
Fig 3.
Postural sway as a function of horizontal gaze and head position (gravity).
(A) Postural sway speed (PSS in cm/s) is shown for the gaze straight ahead position and right and left gaze positions (20°). PSS differed between groups but not within groups, i.e. PSS was not gaze dependent. (B) PSS is shown for different head positions in the straight ahead gaze position: head forward (45°), erect, and backward (30°) bended head position. PSS differed between groups but not within groups, i.e. PSS was not gravity dependent.
Fig 4.
Postural sway as a function of proprioceptive deprivation and higher demand (tandem stance).
PSS increased with attenuated proprioceptive input (standing on foam) in both groups (A, B). PSS of patients was significantly higher in both conditions (eyes open and closed). However, there was no significant difference in the increase in PSS between both groups in the foam condition; both with the eyes open and closed (Romberg’s ratio). (C) PSS of patients was significantly higher during tandem stance in both conditions (eyes open and closed) but Romberg’s ratio did not differ between groups (D).
Fig 5.
Relation of behavioral parameters to cerebellar grey matter volume changes.
Significant (FWE-corrected) gray matter volume reductions in DBN patients (healthy controls > patients) are depicted in cerebellar vermis (lobules VI and VIII and deep cerebellar nuclei) and cerebellar hemispheric lobules (V-VI) in axial and sagittal slices (p<0.001). GMV reduction (ROI of vermal cluster) increases with stronger impairment (gain) of smooth pursuit eye movements (B). Blue (healthy control) and red (patients) circles show individual data, crosses indicate the mean of gain and ROI-based volume ± standard deviation.