Freezing of gait symptoms in Parkinson’s
disease impairs vision for perception but
not action: evidence from gait with
obstacles
Pieruccini-Faria
1,2
F. ,
Ehgoetz Martens
1,3
K.A. ,
Silveira
1,4
C.R.A. ,
Jones
2
J.A.
1
Q.
, Almeida
1Sun
Life Movement Disorders Research & Rehabilitation Centre & Department of Kinesiology, Wilfrid Laurier University; 2 Department of
Psychology, Wilfrid Laurier University;3Department of Psychology, University of Waterloo;4Department of Kinesiology, University of Waterloo
PURPOSE
HYPOTHESIS
KEY FINDINGS
To evaluate whether vision
for perception and action
are impaired in PD-FOG
Vision for perception and
action will be impaired in
PD-FOG
Only vision for perception
was impaired in PD-FOG
Background
Results
Table 1 - Demographics of the participants
Sex
PD-FOG
14M
PD-nonFOG
10M/3F
CONTROLS
8M/6F
P value
-
Age(years)
73.6(7.7)
69.6(6.1)
74.7(8.2)
.202
UPDRS-III(total)
37.3(5.1)
33.1(10.7)
NA
.236
FOG-Q(Item 3)
3.2(0.8)a
0.38(0.7)
0
.0001
3MS
92.6(6.7)
90.7(14.0)
95.9(3.9)
.340
TMT B-A(s)
267.8(53.9)a,b
119.7(30.5)c
66.8(11.9)
.001
» Vision for Perception
Constant error
http://www.pc.rhul.ac.uk/staff/j.zanker/teach/ps2080/l5/ps2080_5.htm
Figure 1 - Depiction of ventral and dorsal streams.
•
•
•
Vision for perception: Participants were
instructed to say “stop” when they perceived the
height of the measuring tape to match the obstacle
(Figure 2).
*
HC
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
-4.0
-4.5
2.00
1.50
1.00
0.50
0.00
PD FOG
Visuospatial deficits have been hypothesized to
influence gait in individuals with Parkinson’s disease
who experience freezing of gait (PD-FOG)[2],
suggesting an impairment in the dorsal stream [3].
Perceptual deficits have also been found in PDFOG, suggesting an impairment in the ventral
stream [4].
However, it remains unclear which stream is
impaired in PD-FOG and whether these impairments
influence gait.
The aim of current study was to evaluate whether
vision for perception and action are impaired in PDFOG using an obstacle avoidance task during gait.
PD
nonFOG
HC
F(2, 38)=5.80, p=.006
F(2, 38)=1.85, p=.170
*P<0.05
**P<0.01
Perceptual judgement
» Vision for Action
Figure 2 – Vision for perception.
Max toe elevation
variability(SD)
Max toe elevation
•
Vision for action: Participants walked and
stepped over an obstacle. The maximum vertical
distance between the foot and the floor during
obstacle crossing was measured using Optotrak®.
cm
•
cm
•
**
PD
PD FOG nonFOG
Legend - Statistical difference at p<0.05: a)=PD-FOG x PD-NonFOG; b=PD-FOG x Controls; c=PD-Non-FOG x Controls.
Variable error
cm
There are two different streams to process vision[1].
The ventral stream mediates static visual
judgements whereas the dorsal mediates visual
judgements for action (Figure 1).
50.0
3.00
40.0
2.50
2.00
30.0
cm
•
Methods
1.50
20.0
1.00
10.0
0.50
0.0
0.00
PD FOG
Action judgement
PD
nonFOG
PD FOG
HC
F(2, 38)=0.27, p=.764
Discussion and Conclusion
• Although perceptual judgement was not significantly different between groups, all PD participants tended to make more perceptual
errors.
PD
nonFOG
HC
F(2, 38)=2.05, p=.142
Key References
[1]Goodale et al. (1991) Nature
[2]Almeida, Q. & Lebold, C. (2010)
JNNP
• Notably PD-FOG were more variable with perceptual judgement of obstacle height, suggesting an inconsistent contribution of the
ventral stream.
[3]Lord, S. et al (2010)Parkinsonism
& Related disorders
• In contrast PD patients did not demonstrate impairments associated with action judgement, suggesting that the dorsal stream is intact
in PD. However, these results need to be carefully considered, since obstacles may act as visual cues.
[4]Silveira et al (2011) ISPGR-Gait
• Gait impairments in PD-FOG observed in previous studies may be associated with vision for perception deficits
and Mental Function conference/
Norway
Acknowledgments:
The authors would like to thank
Wendy Spiegelberg for patient
recruitment