Daniel C. Kiper

ETH Zurich, Zürich, Zurich, Switzerland

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Publications (69)179.48 Total impact

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    ABSTRACT: Rehabilitative training has shown to improve significantly motor outcomes and functional walking capacity in patients with incomplete spinal cord injury (iSCI). However, whether performance improvements during rehabilitation relate to brain plasticity or whether it is based on functional adaptation of movement strategies remain uncertain. This study assessed training improvement-induced structural brain plasticity in chronic iSCI patients using longitudinal MRI. We used tensor-based morphometry (TBM) to analyze longitudinal brain volume changes associated with intensive virtual reality (VR)-augmented lower limb training in nine traumatic iSCI patients. The MRI data was acquired before and after a 4-week training period (16–20 training sessions). Before training, voxel-based morphometry (VBM) and voxel-based cortical thickness (VBCT) assessed baseline morphometric differences in nine iSCI patients compared to 14 healthy controls. The intense VR-augmented training of limb control improved significantly balance, walking speed, ambulation, and muscle strength in patients. Retention of clinical improvements was confirmed by the 3–4 months follow-up. In patients relative to controls, VBM revealed reductions of white matter volume within the brainstem and cerebellum and VBCT showed cortical thinning in the primary motor cortex. Over time, TBM revealed significant improvement-induced volume increases in the left middle temporal and occipital gyrus, left temporal pole and fusiform gyrus, both hippocampi, cerebellum, corpus callosum, and brainstem in iSCI patients. This study demonstrates structural plasticity at the cortical and brainstem level as a consequence of VR-augmented training in iSCI patients. These structural changes may serve as neuroimaging biomarkers of VR-augmented lower limb neurorehabilitation in addition to performance measures to detect improvements in rehabilitative training.
    Frontiers in Human Neuroscience 05/2015; 9:254. DOI:10.3389/fnhum.2015.00254 · 2.90 Impact Factor
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    ABSTRACT: Background: In recent years, virtual reality has been introduced to neurorehabilitation, in particular with the intention of improving upper-limb training options and facilitating motor function recovery. Methods/Design: The proposed study incorporates a quantitative part and a qualitative part, termed a mixed-methods approach: (1) a quantitative investigation of the efficacy of virtual reality training compared to conventional therapy in upper-limb motor function are investigated, (2a) a qualitative investigation of patients’ experiences and expectations of virtual reality training and (2b) a qualitative investigation of therapists’ experiences using the virtual reality training system in the therapy setting. At three participating clinics, 60 patients at least 6 months after stroke onset will be randomly allocated to an experimental virtual reality group (EG) or to a control group that will receive conventional physiotherapy or occupational therapy (16 sessions, 45 minutes each, over the course of 4 weeks). Using custom data gloves, patients’ finger and arm movements will be displayed in real time on a monitor, and they will move and manipulate objects in various virtual environments. A blinded assessor will test patients’ motor and cognitive performance twice before, once during, and twice after the 4-week intervention. The primary outcome measure is the Box and Block Test. Secondary outcome measures are the Chedoke-McMaster Stroke Assessments (hand, arm and shoulder pain subscales), the Chedoke-McMaster Arm and Hand Activity Inventory, the Line Bisection Test, the Stroke Impact Scale, the MiniMentalState Examination and the Extended Barthel Index. Semistructured face-to-face interviews will be conducted with patients in the EG after intervention finalization with a focus on the patients’ expectations and experiences regarding the virtual reality training. Therapists’ perspectives on virtual reality training will be reviewed in three focus groups comprising four to six occupational therapists and physiotherapists. Discussion: The interviews will help to gain a deeper understanding of the phenomena under investigation to provide sound recommendations for the implementation of the virtual reality training system for routine use in neurorehabilitation complementing the quantitative clinical assessments.
    Trials 09/2014; 15(1):350. DOI:10.1186/1745-6215-15-350 · 2.12 Impact Factor
  • Annals of Physical and Rehabilitation Medicine 05/2014; 57:e85. DOI:10.1016/j.rehab.2014.03.416
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    ABSTRACT: Abstract Purpose: To evaluate feasibility and neurophysiological changes after virtual reality (VR)-based training of upper limb (UL) movements. Method: Single-case A-B-A-design with two male stroke patients (P1:67 y and 50 y, 3.5 and 3 y after onset) with UL motor impairments, 45-min therapy sessions 5×/week over 4 weeks. Patients facing screen, used bimanual data gloves to control virtual arms. Three applications trained bimanual reaching, grasping, hand opening. Assessments during 2-week baseline, weekly during intervention, at 3-month follow-up (FU): Goal Attainment Scale (GAS), Chedoke Arm and Hand Activity Inventory (CAHAI), Chedoke-McMaster Stroke Assessment (CMSA), Extended Barthel Index (EBI), Motor Activity Log (MAL). Functional magnetic resonance imaging scans (FMRI) before, immediately after treatment and at FU. Results: P1 executed 5478 grasps (paretic arm). Improvements in CAHAI (+4) were maintained at FU. GAS changed to +1 post-test and +2 at FU. P2 executed 9835 grasps (paretic arm). CAHAI improvements (+13) were maintained at FU. GAS scores changed to -1 post-test and +1 at FU. MAL scores changed from 3.7 at pre-test to 5.5 post-test and 3.3 at FU. Conclusion: The VR-based intervention was feasible, safe, and intense. Adjustable application settings maintained training challenge and patient motivation. ADL-relevant UL functional improvements persisted at FU and were related to changed cortical activation patterns. Implications for Rehabilitation YouGrabber trains uni- and bimanual upper motor function. Its application is feasible, safe, and intense. The control of the virtual arms can be done in three main ways: (a) normal (b) virtual mirror therapy, or (c) virtual following. The mirroring feature provides an illusion of affected limb movements during the period when the affected upper limb (UL) is resting. The YouGrabber training led to ADL-relevant UL functional improvements that were still assessable 12 weeks after intervention finalization and were related to changed cortical activation patterns.
    Disability and rehabilitation. Assistive technology 04/2014; DOI:10.3109/17483107.2014.908963
  • World Congress of Neurology (WCN) - Journal of the Neurological Sciences; 333:e551; 10/2013
  • Journal of the Neurological Sciences 10/2013; 333:e549. DOI:10.1016/j.jns.2013.07.1929 · 2.26 Impact Factor
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    ABSTRACT: BACKGROUND: . Neurorehabilitation interventions to improve lower limb function and neuropathic pain have had limited success in people with chronic, incomplete spinal cord injury (iSCI). OBJECTIVE: We hypothesized that intense virtual reality (VR)-augmented training of observed and executed leg movements would improve limb function and neuropathic pain. METHODS: . Patients used a VR system with a first-person view of virtual lower limbs, controlled via movement sensors fitted to the patient's own shoes. Four tasks were used to deliver intensive training of individual muscles (tibialis anterior, quadriceps, leg ad-/abductors). The tasks engaged motivation through feedback of task success. Fourteen chronic iSCI patients were treated over 4 weeks in 16 to 20 sessions of 45 minutes. Outcome measures were 10 Meter Walking Test, Berg Balance Scale, Lower Extremity Motor Score, Spinal Cord Independence Measure, Locomotion and Neuropathic Pain Scale (NPS), obtained at the start and at 4 to 6 weeks before intervention. RESULTS: . In addition to positive changes reported by the patients (Patients' Global Impression of Change), measures of walking capacity, balance, and strength revealed improvements in lower limb function. Intensity and unpleasantness of neuropathic pain in half of the affected participants were reduced on the NPS test. Overall findings remained stable 12 to 16 weeks after termination of the training. CONCLUSIONS: . In a pretest/posttest, uncontrolled design, VR-augmented training was associated with improvements in motor function and neuropathic pain in persons with chronic iSCI, several of which reached the level of a minimal clinically important change. A controlled trial is needed to compare this intervention to active training alone or in combination.
    Neurorehabilitation and neural repair 10/2013; 27(8):675-683. DOI:10.1177/1545968313490999 · 4.62 Impact Factor
  • International Neurorehabilitation Symposium (INRS); 09/2013
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    ABSTRACT: The combination of first-person observation and motor imagery, i.e. first-person observation of limbs with online motor imagination, is commonly used in interactive 3D computer gaming and in some movie scenes. These scenarios are designed to induce a cognitive process in which a subject imagines himself/herself acting as the agent in the displayed movement situation. Despite the ubiquity of this type of interaction and its therapeutic potential, its relationship to passive observation and imitation during observation has not been directly studied using an interactive paradigm. In the present study we show activation resulting from observation, coupled with online imagination and with online imitation of a goal-directed lower limb movement using functional MRI (fMRI) in a mixed block/event-related design. Healthy volunteers viewed a video (first-person perspective) of a foot kicking a ball. They were instructed to observe-only the action (O), observe and simultaneously imagine performing the action (O-MI), or imitate the action (O-IMIT). We found that when O-MI was compared to O, activation was enhanced in the ventralpremotor cortex bilaterally, left inferior parietal lobule and left insula. The O-MI and O-IMIT conditions shared many activation foci in motor relevant areas as confirmed by conjunction analysis. These results show that (i) combining observation with motor imagery (O-MI) enhances activation compared to observation-only (O) in the relevant foot motor network and in regions responsible for attention, for control of goal-directed movements and for the awareness of causing an action, and (ii) it is possible to extensively activate the motor execution network using O-MI, even in the absence of overt movement. Our results may have implications for the development of novel virtual reality interactions for neurorehabilitation interventions and other applications involving training of motor tasks.
    PLoS ONE 08/2013; 8(8):e72403. DOI:10.1371/journal.pone.0072403 · 3.53 Impact Factor
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    ABSTRACT: Sensory impairments resulting from stroke increase the difficulty of performing activities of daily living and motor rehabilitation. Despite this, present-day VR rehabilitation systems do not assess tactile sensory function, nor provide feedback to help retraining of tactile perception. We assessed the use of low-cost vibration motors to provide elaborate feedback by investigating various parameters of vibration perception such as the absolute and difference thresholds at the fingertips. Tests conducted with healthy subjects resulted in consistent absolute and difference thresholds, and nearly constant Weber fractions. The data will be of use for calibrating and designing future tactile sensory training systems.
    Virtual Rehabilitation (ICVR), 2013 International Conference on; 01/2013
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    ABSTRACT: The Life Science Learning Center (LSLC) was officially founded in 2005. It is a branch of the pre-existing Life Science Zurich, an organization created by and belonging to the University of Zurich and the Swiss Federal Institute of Technology Zurich to promote and support life sciences in several central parts of society. The LSLC's primary goals are to offer educational opportunities for school children as well as continuing education for teachers of the primary and secondary school levels. In particular, the LSLC facilitates various types of interactions between schools and the higher educational and research institutions (University of Zurich and Federal Institutes of Technology): it offers practicals for pupils in a special laboratory, tours of professional research laboratories, pedagogical training for future biology teachers, and specialized modules of continuing education for teachers. It also contributes to diverse initiatives promoting life sciences in the general public. It is led by a small team of dedicated people based on the Irchel Campus of the University of Zurich.
    CHIMIA International Journal for Chemistry 11/2012; 66(11):853-6. DOI:10.2533/chimia.2012.853 · 1.09 Impact Factor
  • Neuroscience Centre Zurich Symposium (ZNZ) / Neural Plasticity and Repair Symposium (NCCR); 06/2012
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    ABSTRACT: Adaptation is widely used as a tool for studying selectivity to visual features. In these studies it is usually assumed that the loci of feature selective neural responses and adaptation coincide. We used an adaptation paradigm to investigate the relationship between response and adaptation selectivity in event-related potentials (ERPs). ERPs were evoked by the presentation of colored Glass patterns in a form discrimination task. Response selectivities to form and, to some extent, color of the patterns were reflected in the C1 and N1 ERP components. Adaptation selectivity to color was reflected in N1 and was followed by a late (300-500 ms after stimulus onset) effect of form adaptation. Thus for form, response and adaptation selectivity were manifested in non-overlapping intervals. These results indicate that adaptation and response selectivity can be associated with different processes. Therefore, inferring selectivity from an adaptation paradigm requires analysis of both adaptation and neural response data.
    Frontiers in Human Neuroscience 04/2012; 6:89. DOI:10.3389/fnhum.2012.00089 · 2.90 Impact Factor
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    ABSTRACT: It is known that activity in secondary motor areas during observation of human limbs performing actions is affected by the observer's viewpoint, with first-person views generally leading to stronger activation. However, previous neuroimaging studies have displayed limbs in front of the observer, providing an offset view of the limbs without a truly first-person viewpoint. It is unknown to what extent these pseudo-first-person viewpoints have affected the results published to date. In this experiment, we used a horizontal two-dimensional mirrored display that places virtual limbs at the correct egocentric position relative to the observer. We compared subjects using the mirrored and conventional displays while recording over the premotor cortex with functional near-infrared spectroscopy. Subjects watched a first-person view of virtual arms grasping incoming balls on-screen; they were instructed to either imagine the virtual arm as their own [motor imagery during observation (MIO)] or to execute the movements [motor execution (ME)]. With repeated-measures anova, the hemoglobin difference as a direct index of cortical oxygenation revealed significant main effects of the factors hemisphere (P = 0.005) and condition (P ≤ 0.001) with significant post hoc differences between MIO-mirror and MIO-conventional (P = 0.024). These results suggest that the horizontal mirrored display provides a more accurate first-person view, enhancing subjects' ability to perform motor imagery during observation. Our results may have implications for future experimental designs involving motor imagery, and may also have applications in video gaming and virtual reality therapy, such as for patients following stroke.
    European Journal of Neuroscience 04/2012; 35(9):1513-21. DOI:10.1111/j.1460-9568.2012.08062.x · 3.67 Impact Factor
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    ABSTRACT: Trial-to-trial variability is a well-known issue in brain signals measured using functional near-infrared spectroscopy (fNIRS). We aimed to investigate whether trial-to-trial variability does provide information about individual performance. Seventeen subjects observed a virtual reality grasping task in first-person view while either imagining (motor imagery during observation, MIO) or imitating (motor execution, ME) the movements. Each condition was performed with the display in one of two positions, a conventional vertical position and a mirrored horizontal position which placed the virtual arm in the correct position relative to the viewpoint. Averaged oxy-hemoglobin concentration Δ[O(2)Hb] showed that the responses could be differentiated into two distinct groups: low responders (LR) and high responders (HR). Within groups, two main sources of trial-to-trial variability were identified: (a) the Δ[O(2)Hb] amplitude, with largest amplitudes in ME conditions (group HR) and smallest amplitudes in MIO conditions (group LR), and (b) the sign of Δ[O(2)Hb], with positive responses occurring most frequently during ME (group HR) and negative responses most frequently during MIO (group LR). Furthermore, the trial-to-trial dynamics differed between groups and could be described in group LR as inverted polynomial U-shaped curve in the mirror conditions (ME-mirror, MIO-mirror). Last, trial-to-trial variability was significantly dependent on task modality, i.e. ME (group HR) versus MIO (group LR), and/or the mirrored display positions (group LR). Our results show a relationship of trial-to-trial variability to individual MI performance, which may be of significance for neurorehabilitation applications. Although the sources of trial-to-trial variability remain unknown, we suggest that they may contribute to future neurofeedback applications.
    Behavioural brain research 04/2012; 229(1):29-40. DOI:10.1016/j.bbr.2011.12.038 · 3.39 Impact Factor
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    ABSTRACT: Many patients experience severe motor, proprioception and tactile sensory loss following central or peripheral nervous system injury such as Guillain-Barre syndrome (GBS). For many, there are no traditional therapies available and patients fail to use the hand and arm dramatically affecting their quality of life. Our project investigates technology assisted protocols to help re-calibrate body perceptions and improve sensory dependent motor skills. We designed, built and tested an easy to use system to provide technology assistance to a variety of underserved patients, and therapists. The Sensory Motor Training Station (SMTS) accommodates the patient’s lost sensory and motor skills and is used to train cognitive, sensory, motor, and proprioception skills. Virtual Reality (VR) is used with immersive virtual limbs and real objects to increase sense of involvement, and provide tactile experiences in a real world integrated arm and hand task. Robot assistance as needed or transparent mode is provided to overcome patient weakness and promote practice plasticity. We trained a person suffering from GBS. The patient successfully exercised and skills were assessed using the system. SMTS can easily be adapted to accommodate left or right limb, heterogeneous patients, and individual cognitive, sensory and motor issues. Results revealed patient performance varies in each sensory and motor training condition; performance improved in the presence of real objects and also during voluntary motor participation in the exercises facilitated by the robot transparent mode support against gravity and friction. Our multi-sensory technology assistance system provided exercise and assessment for both upper limbs in a real world integrated hand and arm task.
    IASTED Biomedical Engineering; 02/2012
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    Behavioural Brain Research 01/2012; 229(1):29-40. · 3.39 Impact Factor
  • European Neurorehabilitation Congress (ENRC); 10/2011
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    ABSTRACT: Spinal cord injury (SCI) causes both lower limb motor dysfunction and associated neuropathic pain. Although these two conditions share related cortical mechanisms, different interventions are currently used to treat each condition. With intensive training using entertaining virtual reality (VR) scenarios, it may be possible to reshape cortical networks thereby reducing neuropathic pain and improving motor function. We have created the first VR training system combining action observation and execution addressing lower limb function in incomplete SCI (iSCI) patients. A particular feature of the system is the use of size-adjustable shoes with integrated motion sensors. A pilot single-case clinical study is currently being conducted on six iSCI patients. Two patients tested to date were highly motivated to perform and reported improved physical well-being. They improved in playing skill and in controlling the virtual lower limbs. There were post-intervention indications of neuropathic pain decrease, muscle strength increase, faster walking speed and improved performance on items relevant for ambulation. In addition functional MRI before and after treatment revealed a decreased activation pattern. We interpret this result as an improvement of neuronal synergies for this task. These results suggest that our VR system may be beneficial for both reducing neuropathic pain and improving motor function in iSCI patients.
    International Conference on Virtual Rehabilitation (ICVR); 06/2011
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    ABSTRACT: Trial-to-trial variability is a well-known issue in brain signals measured by functional near-infrared spectroscopy (fNIRS) and other modalities. The aim of this study was to quantitatively characterize the variations from trial-to-trial. We recorded fNIRS during motor imagery (MI) and motor execution (ME) in a virtual reality (VR) system. The results of the averaged Δ[O2Hb] fNIRS responses during the two tasks showed that two distinct groups could be differentiated: low responders (LR) and high responders (HR). Within these groups, distinct oxygenation pattern of trial-to-trial variability were identified. Our findings show a relationship of trial-to-trial variability to individual performance in MI, which may be of significance for applications of MI in neurorehabilitation.
    Virtual Rehabilitation (ICVR), 2011 International Conference on; 01/2011

Publication Stats

2k Citations
179.48 Total Impact Points


  • 2002–2014
    • ETH Zurich
      • Institute of Neuroinformatics
      Zürich, Zurich, Switzerland
  • 2003–2013
    • University of Zurich
      • Institute of Neuroinformatics
      Zürich, Zurich, Switzerland
    • Justus-Liebig-Universität Gießen
      • Department of Psychology
      Gießen, Hesse, Germany
  • 2000
    • University of Lausanne
      Lausanne, Vaud, Switzerland
  • 1992–1998
    • Howard Hughes Medical Institute
      Ashburn, Virginia, United States
  • 1994–1997
    • CUNY Graduate Center
      New York City, New York, United States