Failure to modulate neural response to increased task demand in mild Alzheimer's disease: fMRI study of visuospatial processing

Vannini, P; Lehmann, C; Dierks, T; Jann, K; Viitanen, M; Wahlund, L.O.; Almkvist, O (2008). Failure to modulate neural response to increased task demand in mild Alzheimer's disease: fMRI study of visuospatial processing. Neurobiology of disease, 31(3), pp. 287-297. Amsterdam: Elsevier 10.1016/j.nbd.2008.04.013

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Alzheimer's disease (AD) is characterized by disturbances of visuospatial cognition. Given that these impairments are closely related to metabolic and neuropathological changes, our study aimed to investigate the functional competency of brain regions in the visuospatial networks responsible for early clinical symptoms in AD using event-related functional magnetic resonance imaging (fMRI). Participants (13AD patients with mild symptoms and 13 age- and education-matched controls) performed an angle discrimination task with varying task demand. Using a novel approach that modeled the dependency of the blood oxygenation level-dependent (BOLD) signal on the subject's reaction time allowed us to investigate task demand-dependent signal changes between the groups. Both groups demonstrated overlapping neural networks engaged in angle discrimination, including the parieto-occipital and frontal regions. In several network regions, AD patients showed a significantly weaker and sometimes no BOLD signal due to increased task demand compared with controls, demonstrating failure to modulate the neural response to increased task demand. A general task demand-independent increase of activation in AD patients compared with controls was found in right middle temporal gyrus. This latter finding may indicate an attempt to compensate for dysfunctional areas in the dorsal visual pathway. These results confirm deficits in visuospatial abilities, which occur early in AD, and offer new insights into the neural mechanisms underlying this impairment.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > University Psychiatric Services > University Hospital of Psychiatry and Psychotherapy > Psychiatric Neurophysiology [discontinued]
UniBE Contributor:	Vannini, Patrizia, Lehmann, Christoph, Dierks, Thomas, Jann, Kay
ISSN:	0969-9961
ISBN:	287-297
Publisher:	Elsevier
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 15:03
Last Modified:	05 Dec 2022 14:19
Publisher DOI:	10.1016/j.nbd.2008.04.013
PubMed ID:	18619845
Web of Science ID:	000258862000001
URI:	https://boris.unibe.ch/id/eprint/27596 (FactScience: 108943)