Relevance of in vivo Neurophysiological Biomarkers for Mild Cognitive Impairment and Alzheimer's Disease

Issue title: Predictive Biomarkers for Alzheimer's Disease using State-of-the-Art Brain Imaging Techniques

Guest editors: Pravat K. Mandal

Article type: Review Article

Authors: Yamasaki, Takao^{a; b; *} | Horie, Shizuka^a | Muranaka, Hiroyuki^c | Kaseda, Yumiko^d | Mimori, Yasuyo^e | Tobimatsu, Shozo^a

Affiliations: [a] Department of Clinical Neurophysiology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan | [b] Department of Neurology, Minkodo Minohara Hospital, Fukuoka, Japan | [c] Department of Radiology, Hiroshima City General Rehabilitation Center, Hiroshima, Japan | [d] Department of Neurology, Hiroshima City General Rehabilitation Center, Hiroshima, Japan | [e] Department of Physical Therapy, Faculty of Health Sciences, Hiroshima International University, Hiroshima, Japan

Correspondence: [*] Correspondence to: Takao Yamasaki, M.D., Ph.D., Department of Clinical Neurophysiology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan. Tel.: +81 92 642 5542; Fax: +81 92 642 5545; E-mail: yamasa@neurophy.med.kyushu-u.ac.jp.

Abstract: Visuospatial dysfunction including defects in motion perception in Alzheimer's disease (AD) and mild cognitive impairment (MCI) are clues to search for potential in vivo biomarkers. In this review, we focus on the clinical relevance of non-invasive neurophysiological findings in event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI) to assess visual dysfunction in AD and MCI. We first summarize the current concept of the parallel visual pathways in primates and humans. Next, we outline the results of previous electrophysiological and fMRI studies on visual function in AD and MCI. Finally, we present the recent findings of our systematic ERP and fMRI approach to visual perception in AD and MCI. Our overview strongly indicates that visual impairments in patients with AD and MCI are mainly caused by dysfunction in higher-level parallel visual pathways. In particular, a deficit in ventro-dorsal stream function related to optic flow perception is responsible for the earliest and most prominent visual symptoms in MCI. Therefore, we conclude that ERP and fMRI measurements for visual perception can be used as in vivo biomarkers for early functional brain changes in MCI and AD patients.

Keywords: Alzheimer's disease, dorsal and ventral streams, event-related potentials, functional magnetic resonance imaging, mild cognitive impairment, visual perception

DOI: 10.3233/JAD-2012-112093

Journal: Journal of Alzheimer's Disease, vol. 31, no. s3, pp. S137-S154, 2012