Author/Editor		Fernandez, R; Kavcic, V; Duffy, CJ
Title		Neurophysiologic analyses of low- and high-level visual processing in Alzheimer disease
Type		članek
Source		Neurology
Vol. and No.		Letnik 68, št. 24
Publication year		2007
Volume		str. 2066-76
Language		eng
Abstract		Objective: We developed visual motion evoked potential (EP) measures related to navigational impairment in Alzheimer disease (AD) and have now applied these methods to explore the role of elementary perceptual and attentional mechanisms mediating these effects. Methods: Older adult (OA) control subjects and AD patients underwent visual motion perceptual testing, attentional performance monitoring, and basic neuropsychological and visual assessments. We recorded stationary pattern onset and visual motion onset EPs as well as behavioral event-related potentials during centered visual fixation. Results: Psychophysical assessment demonstrated visual motion perceptual impairments in patients with AD, half of whom also showed low sensitivity in the attentional task. The low sensitivity AD patients had small pattern onset and absent motion onset EPs, whereas the high sensitivity AD patients had large pattern onset EPs and normal motion onset EPs. Conclusion: We conclude that visual evoked potentials (EPs) are abnormal in all patients with Alzheimer disease (AD): Those with small pattern and motion onset EPs may have greater AD pathology in visual cortex, whereas those with larger pattern onset EPs may have greater AD pathology in higher centers. These findings highlight the utility of visual EPs in distinguishing between syndromic variants of AD associated with particular patterns of functional decline.
Descriptors		EVOKED POTENTIALS, VISUAL AGED ATTENTION ELECTROENCEPHALOGRAPHY MOTION PERCEPTION NEUROLOGIC EXAMINATION NEUROPSYCHOLOGICAL TESTS ORIENTATION PERCEPTUAL DISORDERS PREDICTIVE VALUE OF TESTS SPACE PERCEPTION VISION DISORDERS VISUAL CORTEX VISUAL PATHWAYS