Date post: | 04-Aug-2015 |
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Optimizing Motor Imagery Neurofeedback through the Use of Multimodal Immersive Virtual Reality and Motor Priming
Athanasios (Thanos) Vourvopoulos - John Edison Muñoz Cardona - Sergi Bermudez i Badia
University of Madeira / M-ITI
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• So far, the development of Brain–Computer Interfaces (BCIs) that translate brain activity into control signals in computers or external devices provide new strategies to overcome stroke-related motor limitations
Interfacing the Brain with the Computer
Signal Processing
Signal Acquisition
End Effector
Control SignalRaw EEG
Motor Imagery
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Why Is Motor Imagery (MI) Important?
• MI is relying on the same brain systems that would be used for actual performance of the task (Miller
et al., 2010).
• Repeated practice of MI can induce plasticity changes in the brain (Jackson et al., 2001)
• Combination of MI and BCI could augment rehabilitation gains (Ang et al., 2011)
Miller, K. J., Schalk, G., Fetz, E. E., Nijs, M. den, Ojemann, J. G., & Rao, R. P. N. (2010). Cortical activity during motor execution, motor imagery, and imagery-based online feedback. Proceedings of the National Academy of Sciences of the United States of America, 107(9),4430-5.
Movement Imagery
How can Motor Priming (MP) be utilized for neurorehabilitation?
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• Motor priming is a possible way to facilitate motor learning (Stoykov, ME et al., 2015)
• Priming of the motorcortex is associated with changes in neuroplasticity that are associated with improvements in motor performance (Stinear, CM et al., 2008)
• So far, MP has not been tested in BCI training
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BCI’s in Stroke Rehabilitation
Closed-Loop Robotic Control for Stroke Rehabilitation,Max Planck Institute for Intelligent Systems
Inclusion of patients with limited/no active movement
Boosts motor imagery practice during stroke recovery
Functional and structural plasticity and recovery
Long and repetitive training resulting in user fatigue
No standardized and accepted treatment for the use of BCIs
Little is known about how a BCI may affect brain plasticity through sensori-motor cortex oscillations
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How Can we Optimize Training
Maximize the engagement of:1. Users
2. Sensory-motor networks
Development of multimodal feedback, in an immersive VR environment
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Methodology - BCI Training Task Design
(a) Feedback level
(b) Instructions level (c) Task level
Incorporated all the necessary properties of a good instructional design (Lotte et al. 2013)
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Methodology - Experimental Setup
Clear Goals and FeedbackPositive reinforcementChallenging task Immersive VR
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Methodology - Experimental Setup
EEG Signal Acquisition
HMD
Hand Tracking
Stereo Sound
g.MOBIlab+Oculus Rift (DK1)Leap Motion
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Methodology - Experimental Conditions
VR-MP:Virtual Reality-Motor
Priming
VR:Virtual Reality
Control : Standard Motor
Imagery
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Methodology - Experimental Design
VR-MP:Virtual Reality-Motor Priming
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Methodology - Experimental Design
VR:Virtual Reality
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Methodology - Experimental Design
Control : Standard Motor
Imagery
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Methodology - Experimental Design
MI-BCI Training
MI-BCI Session
QuestionnairesRest
8 min 8 min15 min 10 min
Equipment Setup
10-15 min
Motor Priming
8 minutes
8 min
1 Condition/Day per User
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• 9 healthy participants (1 female)• Mean Age: 27 ± 2• 1 Left handed• Voluntary sample• No previous known neurological disorder• No previous experience in BCIs
Methodology - Participants
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Methodology - Data
QuestionnairesClassifier Score % (LDA)
Raw EEG (Rhythms)
Presence Questionnaire
(PQ)
Kinaesthetic Imagery (KI)
NASA TLX: workload
Alpha (8 - 12 Hz)
Beta (12 - 30 Hz)
Theta (4 - 7 Hz)
Gamma (25- 100 Hz)
Methodology: Extracting the EEG Rhythms
17
Rhythms
Seconds
Alpha
Beta
Theta
Gamma
Raw EEG
ECG
EMG
7 - 14 Hz
15 - 30 Hz
4 - 7 Hz
30 - 100 Hz
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Results: Do conditions modulate brain activity patterns?
Is associated with• Drowsiness• Concentration• Visual fixation (J. M. Stern, 2005)
VR-MP VR Control
Mea
n Po
wer
(dB)
Alpha (α)
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Results: Do conditions modulate brain activity patterns?
Mea
n Po
wer
(dB) Is associated with
• Motor behavior• Active thinking• Active attention (S. Sanei, J. A. Chambers, 2008)
Beta (β)
VR-MP VR Control
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Results: Do conditions modulate brain activity patterns?
Mea
n Po
wer
(dB) Is associated with
• meditative, relaxed and creative states (S. Sanei, J. A. Chambers, 2008)
VR-MP VR Control
Theta (θ)
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Results: Do conditions modulate brain activity patterns?
Mea
n Po
wer
(dB) Is associated with
• visual, auditory, somatic and olfactory perception
• Attention (J. T. Cacioppo et al., 2007)
Gamma (γ)
VR-MP VR Control
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Results: Do conditions modulate brain activity patterns?
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Results: Do different conditions improve MI-BCI training performance?
MI-BCI Calibration Performance
• VR-MP provides the highest performance
• There is a trend in favor of multimodal setups
• No significant differences between groups
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Results: Is subjective experience modulated by condition?
NASA TLX : Reported workload during BCI
Mean Difference = 17.556 Std. Error = 3.575 Sig: 0.001
TLX questions
*Mental Demand (M=12, STD=5)Physical demand (M=7, STD=5)*Temporal demand (M=7, STD=3)Performance (M=10, STD=4)Effort (M=12, STD=4)*Frustration (M=11, STD=4)
* Significant difference
VR-MP VR Control
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Results: How realistic was the multimodal VR simulation?
70%Realism (M=73, STD=8)
Self-evaluation of performance (M=83, STD=9) Sounds (M=79, STD=12)
Quality of the interface (M=58 ,STD=13 )
Possibility to act (M=77 ,STD=14 )
Presence Questionnaire groups in % (perceived sense of presence during BCI, Cond A)
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Results: Relationship between subjective experience and brain activity
TLX: • Mental Demand
• Temporal Demand
• Kinaesthetic Imagery Kinaesthetic Imagery
TLX: • Effort• Frustration• Physical Demand
PQ: • Quality of Interface
TLX:• Physical Demand
PQ: • Realism• Sounds
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A trend suggesting that multimodal VR feedback and motor priming could increase training performance
Relationship between kinesthetic imagery and Beta band could play an important role as inclusion criteria in neurorehabilitation through MI-BCI paradigms
Discussion
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VR-MP is more mentally demanding task engaging additional neural circuits than in the other 2
conditions
Significant contributions of the VR-MP to the engagement of alpha and beta bands, related with MI practice
increased cortical activation in the affected somatosensory and motor areas
Discussion
ICVR 201529
Extend the study with more participants
Design of a complete MI-BCI game with integrated task-related training
Clinical Validation with stroke survivors
Future Work
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Thank You !
http://neurorehabilitation.m-iti.org/