April 2011
Ishioka T,
Hirayama K, Hosokai Y, Takeda A, Suzuki K, Nishio Y, Sawada Y,Takahashi S, Fukuda H, Itoyama Y, Mori E
Idiopathic Parkinson's disease (PD) is associated with documented
impairments in various visual functions. However, there have been only a
limited number of studies that have reported on the brain regions
responsible for impairment of visual recognition in PD.
In our study, we
evaluated the performance of PD patients and 24 healthy controls on the
Poppelreuter-type overlapping figure identification test to investigate
the impairment of visual recognition. We also measured the PD patients'
resting cerebral glucose metabolism using 18F-fluorodeoxyglucose
positron emission tomography and investigated the relationship between
the impairment of visual recognition and cortical hypometabolism.
The PD
patients had substantial and frequent illusory responses in the
overlapping figure identification test, and their illusory
misidentifications were correlated with hypometabolism in the visual
cortices, including the right inferior temporal gyrus and the bilateral
temporo-parieto-occipital junction.
These findings suggest that PD
patients have impaired visual recognition characterized by illusory
misidentifications of visual stimuli, which could be attributed to
dysfunction of the visual cortices.