MotorControl

ISB 2019 Recap

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Five members of our lab – Kat, Michael, Alyssa, Megan, & Nicole – attended ISB 2019 in Calgary, Canada. The International Society of Biomechanics promotes and supports international contacts amongst scientists, the dissemination of knowledge, and the activities of national organizations in the field of biomechanics.

Four individuals stand in hallway smiling at conference.

Our work at the conference included:

Kat Steele: ISB presentation on in-clinic EMG monitoring for muscle activity and movement in acute care in the initial days after stroke.
Michael Rosenberg: ISB poster showcasing how individuals’ kinematics and muscle activity change in response to ankle exoskeleton stiffness during acceleration from standing. ISB presentation on open-loop modeling of response to ankle exoskeleton torque during walking.
Alyssa Spomer: ISB poster highlighting how motor control is impacted when typically developing individuals emulate cerebral palsy gait patterns. ISB poster on understanding how individuals can alter motor control expression using visual biofeedback.
Megan Auger: ISB presentation on how muscle coordination strategies in typically developing children and children with cerebral palsy are not accurately captured using standard musculoskeletal modeling optimization algorithms in computer simulation.
Nicole Zaino: ISB presentation on spasticity reduction via rhizotomy in children with cerebral palsy and how there was no significant difference in the change in energy consumption when compared to a control group of children with cerebral palsy who had no rhizotomy.

  • Megan stands in blue dress at podium giving a presentation.
  • Nicole stands in a white dress at podium giving a presentation.
  • Michael stands in blue shirt behind a podium presenting.

TGCS 2019

Additionally, two members of our lab – Michael & Megan – attended TGCS 2019 in Canmore, Canada prior to ISB 2019. The Technical Group on Computer Simulation (TGCS) is a scientific and technical meeting for investigators and students in all areas of computer simulation in biomechanics. This group was a highly-focused subset of the ISB community, primarily focusing on forward simulation of unimpaired and pathological gait patterns, but also touching on multi-scale simulation, diving, cycling, and wheelchair use. 

A mountain view in Canmore, Canada with sharp jagged peaks and a bright blue lake.
Michael standing in the front of a room in between two screens giving a presentation.
Michael Rosenberg: TGCS presentation on Dynamic Mode Decomposition for modeling response to ankle exoskeletons during gait.

RehabWeek 2019 Recap

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Modern meets colonial architecture at the huge Toronto Art Museum. An old colonial building sits in front of the modern, glass-fronted art museum.

Five members of our lab – Brandon, Christina, Nick, Michael, & Kat – attended RehabWeek 2019 in Toronto, Canada. This is a unique mega-conference where multiple conferences (ICORR, ACRM, ISPO, RESNA, etc) are hosted at the same time in the same location. Everyone attended common keynotes, poster sessions, and meals. In the morning and afternoon, each conference had their own scientific sessions.

While it was a bit overwhelming to figure out which sessions to attend, it was a great way to get a more diverse audience to provide feedback on your work. For future conferences, I would recommend that students just pick one conference (e.g., ICORR or RESNA) to attend and not bounce between sessions. This lets you more fully engage with a community, have long discussions, and identify common threads across presentations.

Our work at the conference included:

  • Michael Rosenberg: ISPO presented on how muscle coordination differs when you start to walk compared to steady-state walking. Synergies differ during the first step, but quickly converge to steady-state patterns and there was minimal effect of different AFO stiffnesses.
  • Christina Papazian: INERS poster demonstrating correlations between FIM scores and muscle activity in acute stroke care.
  • Brandon Nguyen: ISPO poster on the accuracy and repeatability of using a smartphone to monitor gait for AFO tuning – ISPO Best Student Poster Award
  • Nick Baicoianu: Developer’s Showcase for HuskySTEPS
  • Kat Steele: ISPO poster on synergy-based control of predictive simulations of walking.
Nick demonstrates HuskySTEPS at the Developer's Showcase.

I also served on the IEEE Women in Engineering panel at lunch on Thursday, which focused on new frontiers in technology that could increase accessibility and inclusion. A lot of the discussion focused on the potential of machine learning, wearable technology, and autonomous vehicles.

Flyer from the IEEE Women in Engineering panel with the moderator and four speaker pictures.

You can view our notes and take-aways from the conference in these slides.

We also got to visit with Naser Mehrabi, a former post-doc in the lab, who now works for General Motors. We took the train just north of downtown to visit with him, his wife, and their 9-week-old son. Not only did we get to enjoy some delicious Iranian food, but we also got to get lots of simulation questions answered.

The crew visits with Naser and his wife at their new home in Toronto.

The next RehabWeek will be 2021 in Rotterdam, Netherlands.

Spasticity Research Award Nominations

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Nicole Zaino (wearing glasses) poses on campus

Walking takes energy – but for kids with cerebral palsy, walking can be exhausting. The average child with cerebral palsy consumes two times the amount of energy during walking compared to typically-developing peers – that is the equivalent of jogging or climbing stairs!

The reasons for why walking takes so much energy for children with cerebral palsy remains largely unknown. The extra muscle activity caused by spasticity has often been theorized as a large contributing factor. If this was true, we would expect that treatments that reduce spasticity, like selective dorsal rhizotomy, could dramatically reduce energy during walking.

Led by Nicole Zaino, a new PhD student in the lab, and our collaborator Mike Schwartz at Gillette Children’s Specialty we have been investigating this question. By analyzing energy consumption for children with cerebral palsy who underwent rhizotomy and matched peers with cerebral palsy, we were determined that reducing spasticity does not lead to dramatic decreases in energy consumption.

This research has been nominated as a finalist for two awards at the International Society of Biomechanics Conference. This work was selected as one of 5 finalist for the Clinical Biomechanics Award. Nicole will also present as one of the finalists for the David Winter Young Investigator Award. The final awards will be announced at the conference in Calgary the first week of August. Good luck Nicole!

You can learn more about the study and read the preprint on BioRxiv:

Spasticity reduction in children with cerebral palsy is not associated with reduced energy consumption during walking

N Mehrabi, MH Schwartz, KM Steele (2019) “Can altered muscle synergies control unimpaired gait?” Journal of Biomechanics

Nicole JournalArticle, MotorControl, Publications , , , , ,

Journal Article in Journal of Biomechanics:

Musculoskeletal models of gait with lower dimensional control spaces showed that an individual with reduced number of synergies could not produce an unimpaired gait

Background: Recent studies have postulated that the human motor control system recruits groups of muscles through low-dimensional motor commands, or muscle synergies. This scheme simplifies the neural control problem associated with the high-dimensional structure of the neuromuscular system. Several lines of evidence have suggested that neurological injuries, such as stroke or cerebral palsy, may reduce the dimensions that are available to the motor control system, and these altered dimensions or synergies are thought to contribute to impaired walking patterns. However, no study has investigated whether impaired low-dimensional control spaces necessarily lead to impaired walking patterns.

Methods: In this study, using a two-dimensional model of walking, we developed a synergy-based control framework that can simulate the dynamics of walking.

Results: The simulation analysis showed that a synergy-based control scheme can produce well-coordinated movements of walking matching unimpaired gait. However, when the dimensions available to the controller were reduced, the simplified emergent pattern deviated from unimpaired gait. A system with two synergies, similar to those seen after neurological injury, could not produce an unimpaired walking pattern.

Conclusions: These findings provide further evidence that altered muscle synergies can contribute to impaired gait patterns and may need to be directly addressed to improve gait after neurological injury.

BR Shuman, M Goudriaan, K Desloovere, MH Schwartz, KM Steele (2019) “Muscle synergies demonstrate only minimal changes after treatment in cerebral palsy.” Journal of NeuroEngineering and Rehabilitation

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Journal Article in Journal of NeuroEngineering and Rehabilitation:

In collaboration with University Hospital Pellenberg we examined whether muscle synergies change following common treatments in CP.

Background: Children with cerebral palsy (CP) have altered synergies compared to typically-developing peers, reflecting different neuromuscular control strategies used to move. While these children receive a variety of treatments to improve gait, whether synergies change after treatment, or are associated with treatment outcomes, remains unknown.

Methods: We evaluated synergies for 147 children with CP before and after three common treatments: botulinum toxin type-A injection (n = 52), selective dorsal rhizotomy (n = 38), and multi-level orthopaedic surgery (n = 57). Changes in synergy complexity were measured by the number of synergies required to explain > 90% of the total variance in electromyography data and total variance accounted for by one synergy. Synergy weights and activations before and after treatment were compared using the cosine similarity relative to average synergies of 31 typically-developing (TD) peers.

Results: There were minimal changes in synergies after treatment despite changes in walking patterns. Number of synergies did not change significantly for any treatment group. Total variance accounted for by one synergy increased (i.e., moved further from TD peers) after botulinum toxin type-A injection (1.3%) and selective dorsal rhizotomy (1.9%), but the change was small. Synergy weights did not change for any treatment group (average 0.001 ± 0.10), but synergy activations after selective dorsal rhizotomy did change and were less similar to TD peers (− 0.03 ± 0.07). Only changes in synergy activations were associated with changes in gait kinematics or walking speed after treatment. Children with synergy activations more similar to TD peers after treatment had greater improvements in gait.

Conclusions: While many of these children received significant surgical procedures and prolonged rehabilitation, the minimal changes in synergies after treatment highlight the challenges in altering neuromuscular control in CP. Development of treatment strategies that directly target impaired control or are optimized to an individual’s unique control may be required to improve walking function.