To elucidate how the dorsal visual pathway is functionally altered in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients, first, the neural basis of motion perception in healthy young adults was examined by using visual event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) with coherent motion stimuli such as radial optic flow (OF) and horizontal motion (HO). Nonspecific, motion-related N170 from V5/MT and OF-specific P200 with an inferior parietal lobule (IPL) origin were obtained in ERPs. fMRI revealed the close relationship between IPL activity and OF stimuli. Next, coherent motion perception was assessed by the psychophysical thresholds for patients with AD and MCI, as well as ERPs for MCI patients. MCI patients manifested a selective elevation of the OF threshold, while AD patients exhibited higher psychophysical thresholds for both OF and HO. In ERPs, the P200 latency for OF (but not the N170 latency for OF and HO) was significantly prolonged in MCI patients. These findings indicate that patients with AD and MCI have impaired coherent motion processing due to higher levels of the dorsal pathway. In particular, OF processing related to the IPL is selectively impaired in patients with MCI. Therefore, a combined approach with psychophysics and ERPs using coherent motion (particularly OF) can be useful to discriminate MCI and AD patients from older but healthy adults.
|Title of host publication||Early Detection and Rehabilitation Technologies for Dementia|
|Subtitle of host publication||Neuroscience and Biomedical Applications|
|Number of pages||6|
|Publication status||Published - Dec 1 2011|
All Science Journal Classification (ASJC) codes
- Health Professions(all)