Name: Adaptation of a Haptic Robot in a 3T fMRI (Video) | JoVE Journal
Uploaded: 2011-10-04T12:00:00.000+00:00
Duration: 8 min 16 s
Description: Learn to use a phantom haptic robot during 3T fMRI imaging to assess brain activity during motor tasks in humans. This method enables precise measurements of arm position and applied force with minimal electrical interference.

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We would like to thank Kun Lu and Ronald Kurz for technical assistance. This work was supported by ONR MURI Award No.:N00014-10-1-0072, NSF grant #SBE-0542013 to the Temporal Dynamics of Learning Center, an NSF Science of Learning Center, and NIH grant #2 R01 NS036449-11.

1. Outside the scanner room
<ol>
<li>Place the rolling table with the free end supported and the exterior end of the long handle detached.</li>
<li>Check that the robot is switched off.</li>
<li>Place the robot in the table socket and secure the aluminum safety plate over the robot with 2 screws.</li>
<li>Attach the end effecter to the robot handle with the aluminum adapter and check that it moves freely.</li>
<li>Attach the 10' parallel cable with aluminum shielding to the robot and check that the shielding is intact. Add extra foil if needed.</li>
<li>Place the aluminum shielding box over the robot being careful to place the parallel and power cables into the groove on the back.</li>
<li>Carefully screw on the shielding box.</li>
<li>Pack aluminum foil into the cable groove on the shielding box and be sure the foil makes contact with the shielding on the parallel cable.</li>
</ol>
2. Moving into the scanner room with two people, A and B
<ol>
<li>Prepare to enter a high magnetic field environment by removing any and all metallic objects including non-ferrous ones, e.g., cell phones, keys, coins, etc...</li>
<li>With person A holding the free end of the robot table and person B stabilizing the box end, roll it free end first until the robot just enters the door of the room.</li>
<li>Person B clips the security rope tethered to an anchor hole on the back of the shielding case and checks that the other end is firmly attached to a wall anchor.</li>
<li>Working together, roll the table into the room and attach it with Velcro straps to the foot of the fMRI table. The robot end of the table must stay as far from the scanner as possible.</li>
<li>Attach the robot's parallel cable to the custom filter on the pass through to the control room, and plug in the robot. The shielding foil on the parallel cable should make contact with the filter.</li>
<li>Attach the exterior part of the long handle (end effecter) and verify that it will enter the bore of the fMRI cleanly.</li>
</ol>
3. In the control room
<ol>
<li>Start the control computer and attach the 6' parallel cable to the robot. Be sure to remove any extra filters that may be on the interior part of the pass through.</li>
<li>Verify that the robot motors are turned off, start up the Phantom calibration routine and verify that the position readouts of the motors from the robot's calibration routine are stable.</li>
<li>Double check the parallel cable connection and that only the large custom filter is attached if the calibration routine cannot see the robot or there are large variations in the motor readout.</li>
<li>Turn on the robot by opening the port on the back of the shielding box and press the switches with a stick.</li>
<li>Restart the calibration routine with the end effecter approximately centered at the end of the conical waveguide. Step through the calibration and check that the box calibration box has the appropriate
haptic interaction.</li>
<li>Attach the TTL output from the fMRI (BNC connector) to the Labjack ADC on the control computer.</li>
</ol>
4. The subject
<ol>
<li>Prepare the subject for a high magnetic field environment with the standard fMRI protocols.</li>
<li>Set up any extra equipment for the experiment, e.g., visual display system. We use the NordicNeuro Lab, Inc. Vision System which provides stereo viewing of visual displays, a feature that is particularly helpful when presenting virtual environments.</li>
<li>After the subject lies down on the table and the head coil is situated, adjust the distance of the robot by loosening the hand screws and sliding the top of the table until the subject can move comfortably.</li>
<li>Guide the table manually by holding onto the robot end while the fMRI table is moving in and out of the bore to prevent the casters from wobbling. Make sure the end effecter goes into the bore and does not catch on the outside.</li>
<li>Run the experiment.</li>
</ol>
5. Break down the setup with two people A and B
<ol>
<li>After the patient exits, remove the exterior end of the long handle and detach the robot table from the fMRI table by undoing the Velcro strap.</li>
<li>From the robot, undo the shielded parallel cable and unplug the power cable.</li>
<li>With person A holding the free end of the robot table and person B guiding the robot end, move the table to the door. At the door, undo the tether, and roll the robot table out to the hall.</li>
<li>Undo all the screws from the shielding box and the two screws from the safety plate and remove the robot.</li>
</ol>
6. Representative results: 
Ideally, the haptic robot and fMRI should not affect each other. We can tell online if the robot is being affected by the fMRI. Generally, if the robot's parallel cable is not properly shielded and filtered, then the readout of the motors will oscillate rapidly. This can be fixed by double checking the aluminum shielding on the cable, that the ferrous core is properly placed on the parallel cable near the robot, and that the only filter to the robot is the custom filter on the scanner room side of the pass through. Detecting errors in the fMRI is really only possible after the data have been reduced and analyzed, but an anatomical scan should be taken early in the study and checked for zipper effects or other artifacts indicative of correlated noise (e.g. spike noise) 7. Frequently, such noise comes from metal on metal contact and can be cleaned up by tightening all the screws on the robot table, especially the hand adjustment screws on the side of the table. From our tests the baseline fMRI signal to noise ratio (SNR) is ˜380 and with the robot fully shielded in the room that drops to a still reasonable ˜330. If the shield is not in place on the robot, then the SNR drop further to ˜250, and noise effects become very significant.
As shown in 4, the 3 degree of freedom joint in the center of the handle has little effect on the dynamics of the robot/hand interaction except to shift it away from the robot. The joint in the center of the handle acts like a fulcrum and reverses the apparent motion in two of the directions (left-right and up-down) but not the third (forward-back). Since the Phantom and the hand are at opposite ends of the lever like handle with its fulcrum in the middle, gains are applied in software in each of the three Euclidean directions: negative gains in the two directions controlled by the swivel joint and a positive gain in the direction of the slider joint. The net effect of the handle and swivel reproduces the full 3 degrees of freedom of the Phantom robot, just 9' away.
<img src="/files/ftp_upload/3364/3364fig1.jpg" alt="Electromagnetic safety MRI study with coil setup, shielding diagram, and patient positioning experiment." data-altupdatedat="1788235205000" data-alt="Figure 1"> Figure 1 The apparatus used to mount the haptic robot for use in the fMRI environment. Top shows the haptic robot mounted in the case prior to enclosure (top, left) and the gimbal/slider joint at the midpoint of the handle (top, right). Bottom, left shows a subject in the scanner manipulating the handle. Bottom, right is a cartoon of the shielding and end effecter.
<img src="/files/ftp_upload/3364/3364fig2.jpg" alt="Cryo-electron tomography, cellular structure analysis, microscopy images, 3D reconstruction." data-altupdatedat="1788235205000" data-alt="Figure 2"> Figure 2 Results of the BIRN test for the fully shielded robot with movement. The three images with crosses show sections of the spherical head model, and the bottom right shows a three dimensional view. The small dots are bubbles in the static head model and are always present. The lack of large stripes or zippers indicates that the noise from the robot is uncorrelated.

<ol><li>Ogawa, S., Lee, T. M., Kay, A. R., Tank, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Brain+magnetic+resonance+imaging+with+contrast+dependent+on+blood+oxygenation%5BTitle%5D)+AND+%22Proc.+Natl.+Acad.+Sci.+U.S.A%22%5BJournal%5D)">Brain magnetic resonance imaging with contrast dependent on blood oxygenation.</a> Proc. Natl. Acad. Sci. U.S.A. 87, 9868-9872 (1990).</li>
<li>Heeger, D. J., Ress, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((What+does+fMRI+tell+us+about+neuronal+activity%5BTitle%5D)+AND+%22Nat.+Rev.+Neurosci%22%5BJournal%5D)">What does fMRI tell us about neuronal activity.</a> Nat. Rev. Neurosci. 3, 142-151 (2002).</li>
<li>deCharms, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Applications+of+real-time+fMRI%5BTitle%5D)+AND+%22Nat.+Rev.+Neurosci%22%5BJournal%5D)">Applications of real-time fMRI.</a> Nat. Rev. Neurosci. 9, 720-729 (2008).</li>
<li>Hribar, A., Koritnik, B., Munih, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Phantom+haptic+device+upgrade+for+use+in+fMRI%5BTitle%5D)+AND+%22Medical+and+Biological+Engineering+and+Computing%22%5BJournal%5D)">Phantom haptic device upgrade for use in fMRI.</a> Medical and Biological Engineering and Computing. 47, 677-684 (2009).</li>
<li>Trommershauser, J., Gepshtein, S., Maloney, L. T., Landy, M. S., Banks, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Optimal+compensation+for+changes+in+task-relevant+movement+variability%5BTitle%5D)+AND+%22J.+Neurosci%22%5BJournal%5D)">Optimal compensation for changes in task-relevant movement variability.</a> J. Neurosci. 25, 7169-7178 (2005).</li>
<li>Konczak, J., Li, K. Y., Tuite, P. J., Poizner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Haptic+perception+of+object+curvature+in+Parkinson%27s+disease%5BTitle%5D)+AND+%22PLoS+ONE%22%5BJournal%5D)">Haptic perception of object curvature in Parkinson's disease.</a> PLoS ONE. 3, e2625-e2625 (2008).</li>
<li>Lipton, M. L., Lipton, M. L. Artifacts: When things go wrong, it's not necessarily all bad. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aLipton%2C+ML+%22Totally+Accessible+MRI%22">Totally Accessible MRI</a>. , Springer. New York. 139-153 (2008).</li>
<li>Rajh, M., Glodez, S., Flasker, J., Gotlih, K., Kostanjevec, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Design+and+analysis+of+an+fMRI+compatible+haptic+robot%5BTitle%5D)+AND+%22Robotics+and+Computer-Integrated+Manufacturing%22%5BJournal%5D)">Design and analysis of an fMRI compatible haptic robot.</a> Robotics and Computer-Integrated Manufacturing. 27, 267-275 (2011).</li>
<li>Burdet, E., Gassert, R., Gowrishankar, G., Chapuis, D., Bleuler, H. fMRI compatible haptic interfaces to investigate human motor control. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aBurdet%2C+E+%22Experimental+Robotics+IX%2C+of+Springer+Tracts+in+Advanced+Robotics%22">Experimental Robotics IX, of Springer Tracts in Advanced Robotics</a>. Ang, M., Khatib, O. 21, Springer. Berlin. 25-34 (2006).</li>
<li>Nakamura, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Functional+networks+in+motor+sequence+learning%3A+abnormal+topographies+in+Parkinson%27s+disease%5BTitle%5D)+AND+%22Hum+Brain+Mapp%22%5BJournal%5D)">Functional networks in motor sequence learning: abnormal topographies in Parkinson's disease.</a> Hum Brain Mapp. 12, 42-60 (2001).</li>
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No conflicts of interest declared.

The fMRI compatible robot opens up new possibilities for experiments in the neuroscience of motor control. The most critical step in the setup is the shielding of the robot to prevent artifacts in the fMRI, which we do in two steps. First, the robot itself is about 9' away from the bore with a long, lightweight, handle supported in its middle with a 3 degree of freedom joint . Second, the robot is encased in a 1/16&quot;-1/4&quot; aluminum box with a plastic conical (13&quot; base diameter, 6&quot; top diameter x 42&quo...

<table><tbody><tr><td>Phantom premium 1.5/6dof, high force model</td><td>SensAble, Geomagic</td><td></td><td></td></tr></tbody></table>

adaptation of a haptic robot in a 3t fmri

Adaptation of a Haptic Robot in a 3T fMRI

Functional magnetic resonance imaging (fMRI) provides excellent functional brain imaging via the BOLD signal 1 with advantages including non-ionizing radiation, millimeter spatial accuracy of anatomical and functional data 2, and nearly real-time analyses 3. Haptic robots provide precise measurement and control of position and force of a cursor in a reasonably confined space. Here we combine these two technologies to allow precision experiments involving motor control with haptic/tactile environment interaction such as reaching or grasping. The basic idea is to attach an 8 foot end effecter supported in the center to the robot 4 allowing the subject to use the robot, but shielding it and keeping it out of the most extreme part of the magnetic field from the fMRI machine (Figure 1).
The Phantom Premium 3.0, 6DoF, high-force robot (SensAble Technologies, Inc.) is an excellent choice for providing force-feedback in virtual reality experiments 5, 6, but it is inherently non-MR safe, introduces significant noise to the sensitive fMRI equipment, and its electric motors may be affected by the fMRI's strongly varying magnetic field. We have constructed a table and shielding system that allows the robot to be safely introduced into the fMRI environment and limits both the degradation of the fMRI signal by the electrically noisy motors and the degradation of the electric motor performance by the strongly varying magnetic field of the fMRI. With the shield, the signal to noise ratio (SNR: mean signal/noise standard deviation) of the fMRI goes from a baseline of &tilde;380 to &tilde;330, and &tilde;250 without the shielding. The remaining noise appears to be uncorrelated and does not add artifacts to the fMRI of a test sphere (Figure 2). The long, stiff handle allows placement of the robot out of range of the most strongly varying parts of the magnetic field so there is no significant effect of the fMRI on the robot. The effect of the handle on the robot's kinematics is minimal since it is lightweight (&tilde;2.6 lbs) but extremely stiff 3/4" graphite and well balanced on the 3DoF joint in the middle. The end result is an fMRI compatible, haptic system with about 1 cubic foot of working space, and, when combined with virtual reality, it allows for a new set of experiments to be performed in the fMRI environment including naturalistic reaching, passive displacement of the limb and haptic perception, adaptation learning in varying force fields, or texture identification 5, 6.

The adaptation and use of a haptic robot in a 3T fMRI is described.

Functional magnetic resonance imaging (fMRI) provides excellent functional brain imaging via the BOLD signal 1 with advantages including non-ionizing ...

This video demonstrates how to use a phantom haptic robot during FMR imaging with an ultimate goal of assessing brain activity during motor tasks in humans. When the robot's arm is manipulated by a subject, precise measurements can be made of the arm position and the force applied by the subject. In order to record FMRI in conjunction with haptic robotic manipulations, it is important to avoid having the robot interfere with the FMRI output by introducing too much electrical noise and also to avoid damage to the robot from the MRI's magnetic field.To accomplish this, the robot is first encased in an aluminum shielded box. In addition, the shielded robot is attached to an eight foot effector handle that will be used by the subject during the experiment. The shielding and eight foot handle minimize the disruptive electrical and magnetic fields when the phantom robot is used with the MR scanner.When a subject is placed in the MRI and manipulates the phantom robot's effector arm via the eight foot handle, virtual reality experiments can be done of naturalistic reaching passive displacement of the limb and haptic perception adaptation, learning in varying force fields, and texture identification. Ultimately, this setup can be used to correlate brain activity with movement and planning through functional MRI recordings and kinematic analysis of the robot data. The main advantage of this technique over existing methods like using compressed air or water Tory, the sensory motor interaction is that the haptic robot responds with millisecond latencies even to complex dynamic objects.This method can help answer key questions in the study of neuro control of movement. For example, the brain regions active during haptic interaction with virtual objects. To begin place a rolling table with an aluminum shielded box outside the MRI scanner door.The free end of the table should be supported and the exterior end of the long handle effector detached assure that the robot is switched off. Then place the robot in the table socket and secure the aluminum safety plate over the robot with two screws. Next, attach the end effector to the robot handle and check that it moves freely.Then attach the 10 foot parallel cable with aluminum shielding to the robot, and check that the shielding is intact. Add extra foil if needed. Place the aluminum shielding box over the robot being careful to place the parallel and power cables into the groove on the back.Carefully screw on the shielding box. Pack aluminum foil into the cable groove on the shielding box, and be sure the foil makes contact with the shielding on the parallel cable. Prepare to enter the high magnetic field environment by removing any and all metallic objects and non MR Safe items.Moving the robot into the MRI room requires two people in order to assure that the setup can be brought into the magnetic field safely. With one person holding the free end of the robot table and another person stabilizing the box end roll, the free end forward until the robot just enters the door of the room. The researcher holding the box end should now clip the security rope tethered to an anchor hole on the back of the shielding case.Assure that the other end is firmly attached to a wall Anchor next working together. Roll the table into the room and attach it with Velcro straps to the foot of the FMRI table. The robot end of the table must stay as far away from the scanner as possible.Now attach the robot's parallel cable to the custom filter on the pass through to the control room and plug in the robot. The shielding foil on the parallel cable should make contact with the filter. Finally, attach the exterior part of the end effector being the long handle that the subject will reach to the robot.Verify that the handle will be able to enter the bore of the FMRI cleanly without hitting the side. Once the robot is set up in the scanner, start up the control computer. Then assure only the custom filter is on the interior part of the pass through and attach the six foot parallel cable to the robot.Next, check that the robot motors are turned off. Then start up the phantom calibration routine and verify that the position readouts of the motors are stable. Now turn on the robot by opening the port on the back of the shielding box and activating the switches within the box.Restart the calibration routine with the end effector approximately centered at the end of the conical wave guide. Step through the calibration and check that the calibration box has the appropriate haptic interaction. To begin the experiment, set up any extra equipment for the experiment, such as a visual display system.Here, the Nordic Neuro Lab Incorporated vision system is used, which provides stereo viewing of visual displays. Now have the subject lie down on the scanner table and assure that he or she will be comfortable for the duration of the experiment. Place the head coil and cushioning.Then adjust the distance of the robot by the hand screws and sliding the top of the table until the subject can reach the effector handle and move comfortably. Guide the table into the MRI bore manually by holding onto the robot end while the table is moving. Make sure the end effector is directed into the bore and does not catch on the outside.Finally, run the FMRI experiment. Begin by obtaining an anatomical scan to check for any imaging artifacts. Then run the functional scans while the subject performs the functional task designed for the experiment such as a naturalistic reaching paradigm, the haptic robot and FMRI should not interfere with each other.If the robot is being affected by the FMRI, then the readout of the motors will oscillate rapidly and the online representation of the robot will move even when the robot itself is not moving. In general, this happens when the robot's parallel cable is not properly shielded and filtered. This can be fixed by double checking the aluminum shielding on the cable that the Ferris core is properly placed on the parallel cable near the robot, and that the only filter to the robot is the custom filter on the scanner room side of the pass through.Detecting errors in the FMRI is really only possible after the data have been reduced and analyzed. But an anatomical scan should be taken early in the study and checked for zipper effects or other artifacts indicative of correlated noise. Frequently such noise comes from metal on metal contact and can be cleaned up by tightening all the screws on the robot table, especially the hand adjustment screws on the side of the table.Once mastered, this technique can be completed in about 15 minutes, which is very important for the FMRI. Since time is so expensive While attempting the procedure, it's urgently important to keep in mind the MRI safety protocols since the robot could potentially be drawn into the bar of the MRI.

adaptation-of-a-haptic-robot-in-a-3t-fmri

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Learn to use a phantom haptic robot during 3T fMRI imaging to assess brain activity during motor tasks in humans. This method enables precise measurements of arm position and applied force with minimal electrical interference.

Adaptation of a Haptic Robot in a 3T fMRI

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