Evaluating Tests of Cognition using a Computerized Touch-Sensitive Tablet, Eye Tracking, and Functional Magnetic Resonance Imaging

We develop MRI technology to study brain structure and function. We aim to improve understanding of neurological diseases and support increased use of MRI in clinical applications, including image guided treatments. A touch sensitive digitizing tablet enables naturalistic writing and drawing during functional MRI of brain activity.

This technology provides new opportunities for evaluating brain behavior relationships. fMRI must be done very carefully. The participant must lie supine and keep their head still.

The tablet technology must not produce magnetic forces radio frequency heating or radio frequency interference. The neural circuits engaged by standard cognitive tests involving writing and drawing behavior are poorly understood. Our FMRI results help researchers and clinicians to interpret cognitive test results better.

Investigation of a visual proprioceptive ocular motor and hand motor processes iterate at the levels of brain activity and behavior. Alongside the development of broad ranging fMRI studies with improved ecological validity. To begin, secure the tablet to its frame and attach the MRI compatible video camera.

Apply fresh blue tape across the tablet surface ensuring the entire touch area is covered without major creases. Remove any excess tape from the tablet edges. Bring the tablet, stylus, tablet link cable, and tablet video camera link cables into the magnet room.

Connect the tablet link and video camera. Link cables to the magnet room side of the RF penetration panel. Then slide the MRI compatible tablet clips into the patient table rails, securing two clips on each side.

To fasten the tablet system in place, mount the MRI compatible rear projection screen inside the magnet bore approximately two meters from the projector. Place the MRI compatible eye tracking camera between the projector screen and the outer edge of the magnet bore, ensuring the camera mount is flush with the bore edge. Tighten the plastic screws on the mount to secure the eye tracking system in place.

Now prepare the patient table by installing the 64 channel head coil. Instruct the participant to lie supine on the table and position their head fully into the coil. Place padding around the participant's head to restrict movement and ensure a secure fit.

Secure the head coil and use the landmark laser to confirm that the participant's head is centered within the coil. Adjust the position of the head coil mirror until the participant can see the rear projection screen clearly and without obstruction. Then place the tablet mount across the participant's waist so that the touch sensitive surface rests comfortably to support writing and drawing movements.

Now place the tablet stylus in the participant's dominant hand and instruct them to hold it like a pen. Ask the participant to touch all four corners of the tablet surface with the stylus to assess range and comfort. Adjust the mount position and add padding under the elbow if needed to improve comfort or access using Velcro straps.

Fasten the tablet system to the patient bed. Slowly slide both the participant and tablet system into the magnet bore, ensuring the tablet does not contact the bore edge and the cables remain untangled. On the tablet video camera computer, launch the video camera EXE program.

Then create a new screen capture session for the participant. Following the EyeLink 1000 Plus user manual recommendations, configure pupil and corneal reflection thresholds and calibrate and validate the eye tracking camera. To adjust the eye tracking camera to focus on the participant's right eye switch between camera views, fine tune the lens and modify the illuminator until the view is optimized.

Once the pupil threshold and corneal reflection values are acceptable, document the values and initiate the nine point calibration. Then validate the calibration. Record both the average and maximum validation angle values before proceeding to the FMRI experiment.

Next, use the stimulus response computer to begin calibration of the tablet touch surface. Instruct the participant to use the sty to consecutively touch and release the three targets that appear on the screen within the allotted time limits. Once calibration is complete, launch the referenced graphics editing application.

Instruct the participant to draw freely to confirm accurate sty tracking. Now familiarize the participant with tablet-based writing by asking them to complete a self-paced training task used in essential tremor studies. To familiarize the participant with the TMT, guide them through a simplified training version of TMT-A and TMT-B, each with 12 items.

Then proceed to alternate full-sized versions of TMT-A and TMT-B with rearranged items using experimental task timing. Monitor the participant's performance throughout to ensure the tablet remains properly calibrated and the task is followed accurately. Now begin the eye tracking session by selecting start recording in the screen recorder program on the tablet video camera computer.

Then on the stimulus response computer, open the TMT-Run1_slow. ebs2 Prime script file using E-Run. Input the participant ID and the session number when prompted by the E-Run script.

During the run, assign one lab member to monitor the eye tracking data to ensure a stable signal simultaneously. Have a second lab member observe the participant's performance on the TMT task, ensuring that instructions are being followed and that no technical issues are present, such as unreliable projection or stylist tracking. Ask the second lab member to also document any errors in TMT-A or TMT-B performance along with the associated trial number.

After the run is complete, stop the eye tracker recording In the SR research screen recorder software, perform a single point drift check by selecting Drift Correct. For Run Two, restart the eye tracking recording session on the tablet video camera computer. On the stimulus response computer, open the TMT-Run2_slow.

ebs2 E-Run script file. Enter the same participant ID and session number used in Run One. Repeat the task instructions once the experiment concludes.

Perform one final eye tracking validation and record the average and maximum error values. Then click file followed by close on the eye tracking software to finalize and export the data. Remove the participant from the magnet bore and begin equipment take down.

At last, shut off all computers and equipment. During the initial seconds of both TMT-A and TMT-B, the participants gaze searched for targets before initiating stylus movement across all time intervals shown gaze consistently proceeded the stylus linking motion in both TMT-A and TMT-B. Completion time trended longer for TMT-B than for TMT-A.

Seconds per link showed a trend of being higher for TMT-B than for TMT-A. No significant differences were found between TMT-A and TMT-B in linking period durations, non-linking period durations, total distance, extra distance traveled, or distance per link. Stylus force trended slightly higher during TMT-B compared to TMT-A, and blink count per trial was significantly greater during TMT-B.

Blink rate remained significantly higher in TMT-B even after accounting for completion time differences. The percentage of time spent in fixation was significantly lower during TMT-B than during TMT-A. Functional MRI revealed widespread positive brain activation during both TMT-A and TMT-B compared to visual fixation.

Brain activation included regions such as the cerebellum, parietal lobules, occipital gyri, and frontal areas. No significant brain activation differences were observed when contrasting TMT-B directly against TMT-A.