VR-System zur visuo-haptischen Stimulation bei fMRT Untersuchungen
Kognitive und systemische Humanneurowissenschaften
Zusammenfassung der Projektergebnisse
Studying reaching and grasping movements and their dysfunction with functional magnetic resonance imaging (fMRI) was usually limited to very basic tasks. This was partly due to the constraint of only using MR-compatible materials, to the difficult reproducibility of motion and to the lack of knowledge of the position and motion of the arm and hand. To address these issues and to allow for a broad variety of tasks inside a virtual reality (VR) environment, we developed a VR-system including the MR-Octo, a haptic interface that allows for the manipulation of objects in virtual environments from within the MR-scanner. In addition, we developed a prospective head motion correction system to prevent MR image artifacts due to head motion related to reaching and grasping tasks. Instead of aiming for a device designed for a special task to evaluate a single question of motor neuroscience, the goal was to develop a device that can be used and programmed for lots of different scientific questions and scenarios. Thus, we decided for a design that allowed for the manipulation of objects with seven degrees of freedom (translation, rotation, and grasping) in 3D space. One primary challenge was to always consider the extreme working conditions at the MR scanner with a high static magnetic field and rapidly changing electric and magnetic fields during image acqusition which should not interfere with the electronic and mechanic components of the haptic interface. Also, the interface should not interfere with the acquisition of the MR images. This was done by developing a novel parallel kinematics, employing ultrasonic motors that stay fixed at the base. In a pilot study, we investigated brain activation for the lifting and grasping of different weights within the VR-system and compared the results to performing the task with real weights. The activation maps showed large congruences which validate the conceptual approach but there were also significant differences for example in the visual cortex which will need to be examined further in future studies. Reaching tasks often lead to head motion that follows the time-pattern of the task at hand. Thus, we developed a head motion correction system that updates imaging parameters during the MR scan to follow the motion of the head. This was done by employing small nuclear magnetic resonance (NMR) sensors that were attached to the head. The signal processing hardware for these sensors was developed by collaboration partners from the University of Ulm. We developed a working motion correction system and compared its capabilities to a commercial optical motion tracking system. Unfortunately, there were hardware issues that prevented the use of the system at the same scanner the MR-Octo was designed for. Thus, both, the VR-system and the motion correction system were developed in parallel but could not be tested together in the pilot study. To conclude, we developed a working VR-system and a working system for prospective head motion correction. Both setups can now be used in future studies to further evaluate various motor tasks and the related neuroscientific questions.
Projektbezogene Publikationen (Auswahl)
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Design of a new MR-compatible haptic interface with six actuated degrees of freedom. In Proc. IEEE Int. Conf. Biomed. Robot. Biomechatronics, pages 293–300, 2014
M. A. Ergin, M. Kühne, A. Thielscher, and A. Peer
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Second-order model for rotary traveling wave ultrasonic motors. In Proceedings of the IEEE-RAS 15th International Conference on Humanoid Robots (Humanoids), Seoul, page 991, 2015
R. García-Rochín, M. Kühne, R. Santiesteban-Cos, G. J. R. Astorga, and A. Peer
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Tracking Motion and Resulting Field Fluctuations Using 19F NMR Field Probes. In Proceedings of the 23rd annual meeting of the ISMRM, Toronto, page 266, 2015
M. Eschelbach, P. Chang, J. Handwerker, J. Anders, A. Henning, and K. Scheffler
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A Comparison of 19F NMR Field Probes and an Optical Camera System for Motion Tracking. In Proceedings of the 24th annual meeting of the ISMRM, Singapore, page 0340, 2016
M. Eschelbach, A. Loktyushin, P. Chang, J. Handwerker, J. Anders, A. Henning, A. Thielscher, and K. Scheffler
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A Comparison of Prospective Motion Correction with 19F NMR Field Probes and an Optical Camera. In Proceedings of the 25th annual meeting of the ISMRM, Honolulu, page 1304, 2017
M. Eschelbach, A. Aghaeifar, J. Bause, J. Handwerker, J. Anders, A. Thielscher, and K. Scheffler
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AMoCo, a software package for prospective motion correction. In Proceedings of ISMRM annual meeting Honolulu, HI, USA, page 0305, 2017
A. Aghaeifar, M. Eschelbach, J. Bause, A. Thielscher, and K. Scheffler
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Design and evaluation of a haptic interface with octopod kinematics. IEEE/ASME Transactions on Mechatronics, 22(5):2091–2101, 2017
M. Kühne, J. Potzy, R. García-Rochín, P. van der Smagt, and A. Peer
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An MR-compatible haptic interface with seven degrees of freedom. IEEE/ASME Transactions on Mechatronics, 23(2):624–635, 2018
M. Kühne, M. Eschelbach, A. Aghaeifar, L. von Pflugk, A. Thielscher, M. Himmelbach, K. Scheffler, P. van der Smagt, and A. Peer
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Comparison of prospective head motion correction with NMR field probes and an optical tracking system. Magnetic Resonance in Medicine, 22(5):2091–2101, 2018
M. Eschelbach, A. Aghaeifar, J. Bause, J. Handwerker, J. Anders, E.-M. Engel, A. Thielscher, and K. Scheffler
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Modeling and two-input sliding mode control of rotary traveling wave ultrasonic motors. IEEE Transactions on Industrial Electronics, 65(9):7149–7159, 2018
M. Kühne,R. García-Rochín, R. S. Cos, G. J. R. Astorga, and A. Peer
