J Wu, BR Shuman, BW Brunton, KM Steele, JD Olson, RPN Rao (2016) “Multistep model for predicting upper-limb 3D isometric force application from pre-movement electrocorticographic features.” IEEE Engineering Medicine & Biology

Example of ECoG recording during upper-extremity force production.

Peer-reviewed paper at IEEE Engineering in Medicine & Biology Annual Conference:

Can we estimate upper-extremity force production from electrocorticographic recordings?

Example of ECoG recording during upper-extremity force production.Abstract: Neural correlates of movement planning onset and direction may be present in human electrocorticography in the signal dynamics of both motor and non-motor cortical regions. We use a three-stage model of jPCA reduced-rank hidden Markov model (jPCA-RR-HMM), regularized shrunken-centroid discriminant analysis (RDA), and LASSO regression to extract direction-sensitive planning information and movement onset in an upper-limb 3D isometric force task in a human subject. This mode achieves a relatively high true positive force-onset prediction rate of 60% within 250ms, and an above-chance 36% accuracy (17% chance) in predicting one of six planned 3D directions of isometric force using pre-movement signals. We also find direction-distinguishing information up to 400ms before force onset in the pre-movement signals, captured by electrodes placed over the limb-ipsilateral dorsal premotor regions. This approach can contribute to more accurate decoding of higher-level movement goals, at earlier timescales, and inform sensor placement. Our results also contribute to further understanding of the spatiotemporal features of human motor planning.

Two NIH R01 Grants Funded

NIH logoThe Ability & Innovation Lab is excited to announce that two of our recent grant proposals have been funded! This funding will help to accelerate our mission to improve movement for individuals with neurologic disorders.

Quantifying patient-specific changes in neuromuscular control in cerebral palsyFunded by the National Institute of Neurological Disorders and Stroke, this research will examine how new measures of neuromuscular control can be used to better predict outcomes after multi-level orthopaedic surgery for individuals with cerebral palsy. We will be working in close partnership with Gillette Children’s Specialty Healthcare, one of the leading institutions in the management of pediatric neurological disorders. This research will address the challenge of identifying the best treatment for each individual. Cerebral palsy is caused by a brain injury and every brain injury is unique. We will be using new measures from muscle synergy analysis (see prior work here) to determine how patient-specific measures of control can be used to predict outcomes after surgery.

Ubiquitous rehabilitation to improve movement after neurologic injury: Funded by the joint NSF-NIH Smart & Connected Health Initiative, this research will work in partnership with the University of Texas at Austin to use flexible electrodes to track and train muscle activity after stroke and other neurologic injuries. We know that more practice and use after brain injury increases long-term recovery and function. This research will investigate new pathways for both motivating patients to re-learn to use their muscle and providing doctors and therapists with the data and insight needed to guide and customize therapy.

KM Steele, A Rozumalski, MH Schwartz (2015) “Muscle synergies and complexity of neuromuscular control during gait in cerebral palsy.” Developmental Medicine & Child Neurology

WalkDMC decreased with GMFCS level among individuals with cerebral palsy.

Journal article accepted in Developmental Medicine & Child Neurology:

Kat Steele partnered with Mike Schwartz and Adam Rozumalski of Gillette Children’s Specialty Healthcare to complete one of the largest studies to date of individuals with cerebral palsy. They quantified how neuromuscular control is altered among individuals with cerebral palsy and how this altered control can contribute to impaired function.

WalkDMC decreased with GMFCS level among individuals with cerebral palsy.

Abstract: Individuals with cerebral palsy (CP) have impaired movement due to a brain injury near birth. Understanding how neuromuscular control is altered in CP can provide insight into pathological movement. We sought to determine if individuals with CP demonstrate reduced complexity of neuromuscular control during gait compared with unimpaired individuals and if changes in control are related to functional ability. Muscle synergies during gait were retrospectively analyzed for 633 individuals (age range 3.9–70y): 549 with CP (hemiplegia, n=122; diplegia, n=266; triplegia, n=73; quadriplegia, n=88) and 84 unimpaired individuals. Synergies were calculated using non-negative matrix factorization from surface electromyography collected during previous clinical gait analyses. Synergy complexity during gait was compared with diagnosis subtype, functional ability, and clinical examination measures. Fewer synergies were required to describe muscle activity during gait in individuals with CP compared with unimpaired individuals. Changes in synergies were related to functional impairment and clinical examination measures including selective motor control, strength, and spasticity. InterpretationIndividuals with CP use a simplified control strategy during gait compared with unimpaired individuals. These results were similar to synergies during walking among adult stroke survivors, suggesting similar neuromuscular control strategies between these clinical populations. PDF

Also, make sure you look at the commentary from Diane Damiano. She provides perspective about the utility of synergies for evaluating neuromuscular control in children with cerebral palsy and future challenges.

KM Steele, A Rozumalski, MH Schwartz, “Altered muscle synergies during gait in cerebral palsy are not due to altered kinematics or kinetics.” International Society of Biomechanics (Glasgow, UK) July 15, 2015.

International Society of Biomechanics LogoKat Steele presented our recent work on altered synergies during gait in cerebral palsy and the impact of altered gait patterns at the International Society of Biomechanics conference on July 15, 2015 in Glasgow, Ireland.

MH Schwartz, A Rozumalski, KM Steele, “Dynamic motor control during walking predicts treatment outcomes in cerebral palsy.” International Society of Biomechanics (Glasgow, UK) July 13, 2015.

International Society of Biomechanics LogoKat Steele & Mike Schwartz presented their research demonstrating that synergies measured from EMG are predictive of post-operative outcomes after botulinum toxin injections, selective dorsal rhizotomy, and multi-level orthopaedic surgery. These results will support future research to determine if synergies can be used clinically to quantify patient-specific changes in control and guide treatment planning.

International Society of Biomechanics conference on July 13, 2015 in Glasgow, Ireland.