Research article summary (published 30 Jul 2004):

Optimizing the experimental design for ankle dorsiflexion fMRI.

Full Abstract

Compared to motor studies of the upper limb, few experiments have sought a relationship between blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) sensorimotor signals and the resulting lower limb output. In Experiment 1, using an fMRI simulator system, we determined the optimized experimental protocol based on two design types and four behavioral movement types during ankle dorsiflexion. Experiment 2 involved testing the BOLD sensitivity at 1.5 T during ankle movements. Subjects performed large- and small-amplitude dorsiflexion movement types using an event-related design, with the intent of contrasting spatial and temporal features of the BOLD signal. In both experiments, the subject's behavior was guided by visual biofeedback of their ankle flexion angle, using an MR-compatible fiberoptic tape. From Experiment 1, we found electromyography (EMG) difference voltage ratio of approximately 2:1 for large (40 degrees ) and small (15 degrees ) dorsiflexion, 0.13 mV and 0.07 mV, respectively. In Experimental 2, we found the peak BOLD % signal changes of 1.04% and 0.89%, for large (40 degrees ) and small (15 degrees ) dorsiflexion, respectively. In addition, graded dorsiflexion produced graded BOLD signals in the primary sensorimotor and supplementary motor areas in 10 of 12 healthy young subjects, attesting to the feasibility of lower-limb fMRI at 1.5 T. This study provides insight into the cortical network involved in dorsiflexion using an experimental paradigm that is likely to translate effectively to hemiparetic stroke subjects.

Author information

Author/s: MacIntosh, Bradley J (BJ); Mraz, Richard (R); Baker, Nicole (N); Tam, Fred (F); Staines, W Richard (WR); Graham, Simon J (SJ);

Affiliation: Imaging Research, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. brad.macintosh(-atsign-)utoronto.ca

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: NeuroImage (Neuroimage), published in United States. (Language: eng)

Reference: 2004-Aug; vol 22 (issue 4) : pp 1619-27

Dates: Created 2004/07/27; Completed 2004/10/25; Revised 2006/11/15;

PMID: 15275918, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult Ankle - innervation Biofeedback (Psychology) - physiology Brain Mapping Electromyography Feasibility Studies Female Humans Image Enhancement

Image Enhancement Image Processing, Computer-Assisted Isometric Contraction - physiology Magnetic Resonance Imaging Male Motor Cortex - physiology Nerve Net - physiology Oxygen - blood Somatosensory Cortex - physiology

Associated Chemicals: Oxygen (7782-44-7)

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