Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems
Author(s)Malik, Wasim Qamar; Truccolo, Wilson; Brown, Emery N.; Hochberg, Leigh R.
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The Kalman filter is commonly used in neural interface systems to decode neural activity and estimate the desired movement kinematics.We analyze a low-complexity Kalman filter implementation in which the filter gain is approximated by its steady-state form, computed offline before real-time decoding commences. We evaluate its performance using human motor cortical spike train data obtained from an intracortical recording array as part of an ongoing pilot clinical trial. We demonstrate that the standard Kalman filter gain converges to within 95% of the steady-state filter gain in 1.5[plus-over-minus sign]0.5 s (mean[plus-over-minus sign]s.d.) . The difference in the intended movement velocity decoded by the two filters vanishes within 5 s, with a correlation coefficient of 0.99 between the two decoded velocities over the session length. We also find that the steady-state Kalman filter reduces the computational load (algorithm execution time) for decoding the firing rates of 25[plus-over-minus sign]3 single units by a factor of 7.0[plus-over-minus sign]0.9. We expect that the gain in computational efficiency will be much higher in systems with larger neural ensembles. The steady-state filter can thus provide substantial runtime efficiency at little cost in terms of estimation accuracy. This far more efficient neural decoding approach will facilitate the practical implementation of future large-dimensional, multisignal neural interface systems.
DepartmentHarvard University--MIT Division of Health Sciences and Technology; Massachusetts Institute of Technology. Department of Brain and Cognitive Sciences
IEEE Transactions on Neural Systems and Rehabilitation Engineering
Institute of Electrical and Electronics Engineers
Malik, W Q et al. “Efficient Decoding With Steady-State Kalman Filter in Neural Interface Systems.” IEEE Transactions on Neural Systems and Rehabilitation Engineering 19.1 (2011): 25–34. Web.
Author's final manuscript