The overall goal of this procedure is to demonstrate the use of functional near infrared spectroscopy over the sensory and motor regions of the brain with simultaneous kinematic and EMG monitoring during different motor tasks. This is accomplished by first placing the F nears optos onto the participant's head and aligning it with CZ and the preauricular points. The second step is to place the EMG electrodes over the muscle bellies of target muscles and the reflective markers on the anatomical landmarks.
Next, collect data from the F Ns EMG and the motion capture systems simultaneously while the participant is performing motor tasks. Ultimately, F NS is used to identify differences between the brain activation patterns in those with unilateral and bilateral childhood onset brain injury, and those who develop typically. The main advantage of this technique over existing methods like FMRI is that this technique allows us to study the performance of upright and functional tasks such as gait.
This method can help answer key questions in the neuro rehabilitation field, such as how does the brain reorganize after an injury and what are the consequences of that injury on the performance of motor tasks? The use of this technique in studying motor disorders allows us to measure brain activity while simultaneously quantifying intended, as well as unintended movements through motion capture and electromyography. Generally, individuals new to this method will struggle because accurate setup requires careful hair preparation and placement of ners optos for optimal signal quality.
Assisting us with a demonstration of the procedure today will be Dr.C Ann Zary Gallagher, who is a research physical therapist in our laboratory and Mr.No Robinson, who is an NIH research fellow. We will now describe the procedures involved in N'S data collection. Explain the experimental procedures to the participant and obtain informed consent.
Next, administer the Edinburgh handedness inventory and other clinical examinations and record the participant hair and skin types. Measure and record the participant's height, weight, and age. Then begin the procedure by measuring head circumference, the distance between the nasn and the inion, and the distance between the preauricular points on the right and left ears.
The intersection of the midpoint of the latter two measures is cz, which is marked on the scalp, using a washable marker part hair along the NAS and ian line. If the participant has long hair, fix the hair using braids or ponytails in order to expose the scalp where the optos will be placed. After that, place the F nears probe onto the participant's head taking care to align with CZ and AR al.
Then place the optos directly on the scalp, ensuring there is no hair blocking contact. This is a crucial step because hair can degrade signal quality. Next, attach the Velcro straps to securely hold the optos in place.
Make sure that all the opto cables are lying flat and the optos are perpendicular to the surface of the scalp. If necessary, place a thin piece of foam under the group of opto cables to promote perpendicular alignment of the optos. Now, make sure that the intensity of the light measured at all the detectors is at least 80 decibels, and a heartbeat is clearly visible in the delta OD signal at both 690 and 830 nanometer wavelengths.
If these criteria are not met, check the hair and make sure that it is not blocking the optos. Then adjust the detector gains as needed to maximize the signal intensity.Afterward. Add the reflective markers on NZ ar al and iz on the participant.
Ask the participant to stay still and collect approximately two seconds of motion capture data for these and the F nears opto markers. Next, add a cover with several layers of black felt or other optically absorbent material on top of the f nears optos. To protect the detectors from interference or saturation from the motion capture cameras, ensure that the cables and front panel of the F nears unit are also well shielded using the same optically absorbent material.
Sentium guidelines were followed for electrode placement and skin preparation. In this step, locate the muscle belly of each targeted muscle using anatomical landmarks, palpation during muscle contraction and electrode placement guides. Then place the EMG electrodes oriented to the direction of the muscle fibers.
Next place the reflective markers at the joint landmarks. Collect approximately two seconds of motion capture data while the participant is standing with his arms at 90 degrees shoulder flexion and 90 degrees elbow flexion. Now assist the participant to walk over to the treadmill by supporting the F nears opto cables, and then secure the cables to the ceiling support.
After he is in position, instruct the participant to remain as still and relaxed as possible during rest periods and walk at his predetermined gait speed during the task period while focusing his attention to the small black circle on the screen during data acquisition. After that, dim the lights and begin data acquisition on the motion capture computer and the F nears computer. Play the animation file associated with this task.
Maximize the window so that the image of a black. is located in the participant's line of site, which will his focus point for the duration of the trial. Monitor the participant's performance and provide feedback about speed or extraneous voluntary movements as needed.
At the end of the instructional animation, stop recording on the motion capture EMG and F fne systems. Give the participant an opportunity to rest or shift positions as necessary. In this task, transition the participant to a plinth with movable back and leg support.
Remember to support the f nears opto cables and be careful not to dislodge the motion capture markers or EMG electrodes. Instruct the participant to remain as still and relaxed as possible during rest periods and to cycle at approximately 60 RPM during the task period. Then project the cartoon animation that cues the participant to either rest or move through visual and auditory feedback with the movie window maximized to prevent the participant from monitoring the time.
Now, place a bed table in front of the participant, making sure that the participant's arms are supported on the table at a comfortable position. Then instruct the participant to squeeze a soft object at the speed of once per second during the task period and remain as relaxed as possible during the rest periods. After that, remove the bed table and raise the footrest portion of the plinth up to bring the participant's feet into his view.
Instruct the participant to dorsi flex his ankle at a speed of once per second during the task period and remain as relaxed as possible during the rest periods. At the end of the session, remove the cap. All the reflective markers and EMG electrodes here are examples of skeletal reconstruction, joint angles, and EMG For a left dorsiflexion task, the task period during the trial shown begins at approximately 4.5 seconds and continues until 19.5 seconds.
In this typically developing 13-year-old individual, there is very limited movement at the joints other than the targeted left ankle. In addition, the muscles are generally quiescent during the task as well as rest periods except the tibias anterior muscle that supports the motion. Here is an example of an F nears activation map During a left dorsiflexion task, this blue box outlines the approximate area sampled.
This figure shows the average oxygenated hemoglobin response during a period between five and 10 seconds following the movement onset of one, typically developing adolescent dorsi flexing their left ankle. The blue colors represent no activation while the red areas indicate the regions of increased oxygenated hemoglobin during the task periods Once mastered, this technique can be done in approximately two hours if it is performed properly. One should not forget that working with near infrared light can be hazardous, so precautions such as protecting the researchers and participants'eyes from the light sources should always be taken when doing this procedure.
Following this procedure. Other methods like co-registration with anatomical MRI images and determination of regressors from kinematic and EMG data can be performed. This allows us to answer additional questions like accurate localization of brain activity and neural sources of unintended activity.
After watching this video, you should have a good understanding of how to integrate motion monitoring tools with ners measurements to study activation in sensory and motor regions of the brain during the performance of motor tasks.
