Functional Near Infrared Spectroscopy of the Sensory and Motor Brain Regions with Simultaneous Kinematic and EMG Monitoring During Motor Tasks

Summary

Monitoring brain activity during upright motor tasks is of great value when investigating the neural source of movement disorders. Here, we demonstrate a protocol that combines functional near infrared spectroscopy with continuous monitoring of muscle and kinematic activity during 4 types of motor tasks.

Abstract

There are several advantages that functional near-infrared spectroscopy (fNIRS) presents in the study of the neural control of human movement. It is relatively flexible with respect to participant positioning and allows for some head movements during tasks. Additionally, it is inexpensive, light weight, and portable, with very few contraindications to its use. This presents a unique opportunity to study functional brain activity during motor tasks in individuals who are typically developing, as well as those with movement disorders, such as cerebral palsy. An additional consideration when studying movement disorders, however, is the quality of actual movements performed and the potential for additional, unintended movements. Therefore, concurrent monitoring of both blood flow changes in the brain and actual movements of the body during testing is required for appropriate interpretation of fNIRS results. Here, we show a protocol for the combination of fNIRS with muscle and kinematic monitoring during motor tasks. We explore gait, a unilateral multi-joint movement (cycling), and two unilateral single-joint movements (isolated ankle dorsiflexion, and isolated hand squeezing). The techniques presented can be useful in studying both typical and atypical motor control, and can be modified to investigate a broad range of tasks and scientific questions.

Introduction

Neural imaging during functional tasks has become more portable and cost-efficient using non-invasive functional near-infrared spectroscopy (fNIRS) to identify areas of brain activity by measuring blood flow dynamics at the cortex. The portability of fNIRS is especially useful in the study of upright and functional tasks such as gait¹, which is not possible with other technologies such as functional magnetic resonance imaging (fMRI). This capability is critical in the fields of neurology and neuroscience, and could provide new insights into mechanisms underlying movement disorders in children and adults with cerebral palsy (CP) and other neurological condit....

Protocol

NOTE: This protocol was approved by the Institutional Review Board of the National Institutes of Health (ClinicalTrials.gov identifier: NCT01829724). All participants are given the opportunity to ask questions and provide informed consent prior to their participation. In consideration of changes to the hemodynamic response caused by recent use of vasodilators and vasoconstrictors, participants are asked to refrain from alcohol and caffeine for 24 hr before the experiment³.These animation videos were custom made in our laboratory, but could be recorded with other sounds or images specific to alternative research questions.

1. Set Up....

Results

This protocol coordinates concurrent acquisition of 3 modalities to capture brain blood flow, electrical muscle activity, and kinematic movement of joints while a participant performs motor tasks (Figure 1).

Figure 1.......

Discussion

Simultaneous collection of brain activity from targeted areas of the cortex and quantitative data about how a person is moving presents tremendous potential for improving our understanding of the neural control of movement, both in a typically developing population as well as those with movement disorders. There is also broad application in terms of ages and movement tasks that could be completed, as participants are not restricted to a supine position as they would be for a functional MRI. The specific equipment items a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CW6	TechEn	http://nirsoptix.com/	fNIRS machine with variable number of sources and detectors, depending on the number of modules included
MX system with ten T40-series cameras	Vicon Motion Systems Ltd., Oxford, UK	http://www.vicon.com/System/TSeries	Motion capture cameras
reflective 4 mm markers	Vicon Motion Systems Ltd., Oxford, UK		Markers used by the motion capture cameras to locate fNIRS optodes, Ar, Al, Nz, and hand coordinates.
reflective 9.5 mm markers	Vicon Motion Systems Ltd., Oxford, UK		Markers used by the motion capture cameras to locate arm and leg coordinates. Clusters are used for the limb segments, and markers with offsets are uses for PSIS and Iz to improve reliability in data capture.
Trigno Wireless EMG system	Delsys, Inc. Natick, MA	http://www.delsys.com/products/wireless-emg/	Electromyography
Bertec split-belt instrumented treadmill	Bertec Corporation, Columbus, OH	http://bertec.com/products/instrumented-treadmills.html	Treadmill
ZeroG body-weight support system	Aretech, LLC, Ashburn, VA	http://www.aretechllc.com/overview.html	Track and passive trolley used to support cables, harness can be used for patient safety during gait trials
3DS Max 2013	Autodesk, Inc., San Francisco, CA	http://www.autodesk.com/	3-D animation software used to animate animals for instructional videos
Windows Movie Maker	Microsoft Corporation, Redmond, WA	http://windows.microsoft.com/en-us/windows-live/movie-maker	software used to combine animation footage with music
Audacity	open source	http://audacity.sourceforge.net/	Software used to alter musical beat to appropriate cadence