Dorsal rather than ventral visual pathways discriminate freezing status in Parkinson's disease.
BACKGROUND
Although visuospatial deficits have been linked with freezing of gait (FOG) in Parkinson's disease (PD), the specific effects of dorsal and ventral visual pathway dysfunction on FOG is not well understood.


METHODS
We assessed visuospatial function in FOG using an angle discrimination test (dorsal visual pathway bias) and overlapping figure test (ventral visual pathway bias), and recorded overall response time, mean fixation duration and dwell time. Covariate analysis was conducted controlling for disease duration, motor severity, contrast sensitivity and attention with Bonferroni adjustments for multiple comparisons.


RESULTS
Twenty seven people with FOG, 27 people without FOG and 24 controls were assessed. Average fixation duration during angle discrimination distinguished freezing status: [F (1, 43) = 4.77 p < 0.05] (1-way ANCOVA).


CONCLUSIONS
Results indicate a preferential dysfunction of dorsal occipito-parietal pathways in FOG, independent of disease severity, attentional deficit, and contrast sensitivity.
Institute for Ageing and Health, Newcastle University, Clinical Ageing Research Unit, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK.
Sue
S
Lord
Neil
N
Archibald
Urs
U
Mosimann
David
D
Burn
Lynn
L
Rochester
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000503:physiopathology; D009778:Occipital Lobe / Q000166:cytology / Q000502:physiology; D010296:Parietal Lobe / Q000166:cytology / Q000502:physiology; D010300:Parkinson Disease / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D011795:Surveys and Questionnaires; D014795:Visual Pathways / Q000503:physiopathology*; D014796:Visual Perception / Q000502:physiology*