fMRI Validation of fNIRS Measurements During a Naturalistic Task

The overall goal of this procedure is to compare methodologies and results acquired using functional MRI and functional near infrared spectroscopy or F nears in subjects performing a complex motor task. This is accomplished first by development of a paradigm that can be used in both techniques. The second step is to acquire and process functional images using FMRI.

Next acquire and process functional images using F ns. The final step is to compare observations at comparable brain regions. Ultimately, FMRI and F N'S results are similar across study groups who participated in each methodology.

The main advantage of this technique over existing methods like FMRI is that NERS can be applied in natural settings without extreme sensitivity to movement. Artifacts and exclusion criteria such as magnetic susceptibility are not relevant. Begin by modifying the game dance stance revolution or DDR by editing the details of the SM configuration files.

Using the open source clone of DDR step mania to change timing graphics and music. Using the game song butterfly, modify the DO SM configuration file so that subjects will play using an alternating block design built into the game mechanics alternate 30 seconds of game time with 32nd rest periods. The background graphics will indicate to the player when to play green and when to relax red.

For FMRI data collection restrict movements to left and right arrow button presses using the participant's foot. The overall number of button presses should remain equal for both tasks prior to scanning. Obtain informed consent in accordance with institutional guidelines and screen for MRI safety.

Then explain the rudiments of the game to the subject and allow a few practice runs prior to imaging Instruct subjects to press the corresponding arrow button with their foot as close to the perfect time outlined at the top of the path of the moving arrow, but to minimize head movement as much as possible. When ready to scan first, obtain a structural image prior to gameplay. Then acquire functional magnetic resonance imaging.

Instruct the subject to play the game using the prepared paradigm, but using only left and right arrows to reduce motion artifact when scanning is complete. Perform FMRI bold signal analysis using statistical parametric mapping or SPM software. Also perform group analysis with individual results using second level random effects approach.

Then define a region of interest as the conjunction between the functional cluster and the anatomical mask of superior and middle temporal gyrus obtained from Wake Forest University. Pick Atlas tool for near infrared spectroscopy. Use a multi-channel F nears topography system to record data from Optos arranged into a three by five array.

The interop to distance for each source detector pair should be three centimeters. Begin by orienting the elastic cap containing the array of optical sensors so that it is lined up from the left prefrontal cortex to the left temporal lobe. Assure the most anterior opto in the lowest road is centered on FPZ of the international 10 10 system.

Then align the inferior row of optos in parallel with a line between anatomical landmarks, FPZ and T seven. Once it is in place, tighten the optical probe array to the subject's head and assure it is securely attached using the straps and the chin strap. Attention should be paid to prevent displacement of optos from the head surface.

The source detector pairs should be tight to the head, but not uncomfortable to the subject. For f nears testing, ensure that the total number of arrow presses are identical between FMRI and F N'S tasks and that only the pattern differs. Use an identical paradigm to that of FMRI testing with the addition of the up down arrows compared to only left and right arrows used for FMRI.

Hi.Use a standard four button floor mat button response system for gameplay during F n's testing. Once comfortable in the basics of gameplay, instruct subjects to play 32nd game times with 32nd rest periods. Repeat this five minute game twice with each subject.

Next, use a 3D digitizing pen to determine spatial values of the source and detector opto locations. In each channel of the elastic cap, identify the coordinates of the nasn Ian Oracles and cz immediately before data collection and gameplay. Save text files with the source and detector locations to text files and anatomical coordinates to origin text files.

Process the captured 3D coordinates using the registration option in nears SPM from the main menu. Pick standalone spatial registration. On the next screen, select with 3D digitizer and choose the previously saved others and origin text files using the corresponding dialogue.

Then choose the registration NFRI function to determine spatial representation For F'S analysis, choose the channels to be analyzed based on 3D digitizer information. Select a channel for analysis that has a registration probability of 80%or more in the middle and superior temporal gyrus according to the output of the registration process. Use the results function in SPM eight to determine super threshold voxels at a T value greater than 2.6 or a corresponding P value greater than 0.01.

Then determine the region of interest using overlapping super threshold voxels. To define a cluster inside of an anatomical region, define the superior and middle temporal gyrus using the A A L atlas included in the wake forest pick atlas. In this case, the resulting cluster has 572 2 by two by two millimeter voxels located in the middle temporal gyrus with a peak voxel at coordinate negative 66, negative 24 0 and peak T equals 5.73.

For F N's. Determine the channel of interest from F N'S data using the 3D digitized coordinates which were converted to MNI coordinates using N'S SPM in most subjects. Channel 22 has the highest probability of activity in the defined region of interest.

Determine the averaged event triggered response in the region of interest for FMRI and the corresponding channel in F nears for the duration of the 62nd block of active and rest combined. Compare FMRI and F nears by scaling FMRI data to optimally match the F ns data. Using a linear regression use F ns equals B times FMRI where the regression method obtains the B value so that the root means square value of F Ns minus B times FMRI is minimized.

Finally, compare F and FMRI signals by correlation of the two groups. This figure shows the normalized and averaged raw data from 16 subjects from the FMRI scanning procedure and the 26 subjects from the F Ns protocol. The data were pinned at time zero and the active phase of game interaction took place in the first 30 seconds of the graph.

This figure represents a brain rendering with superimposed channel locations from a single subject. Average traces from channels one and 22 are shown with solid lines representing oxyhemoglobin signals and dash lines representing deoxyhemoglobin signals. Red traces represent music gameplay and blue traces represent non-music gameplay signals from channel one serve as a control example to compare with the region of interest.

Signals in these two regions differ with respect to task response After its development. This technique paved the way for researchers in the field of systems neuroscience to explore the neural activity associated with complex motor tasks in healthy normal subjects. After watching this video, you should have a good understanding of how to compare results acquired using FMRI and fne.