Congratulations to Eli Puterman, recipient of the 2018 ISPNE Curtis Richter Award

UBC KIN faculty member, Jean-Sebastien Blouin, as well as Romain Tisserand, Christopher J Dakin, Machiel HF Van der Loos, Elizabeth A Croft, and Timothy J Inglis have had their paper, “Down regulation of vestibular balance stabilizing mechanisms to enable transition between motor states,” published in the latest edition of the prestigious journal, eLife, which publishes promising research in life and biomedical sciences.

“We set out to discover how we initiate movement in the presence of posture-correcting mechanisms that should oppose movement,” says Jean-Sebastien. “It’s an important question that remains unanswered, despite significant historical discussion. Resolving this question may reconcile theoretical models of movement control and contribute to a better understanding of how we move.”

The aim of the study was to investigate whether the body temporarily suppresses or abruptly reconfigures posture-correcting mechanisms during the transition between standing balance and movement.

“Our ability to stand depends on corrective mechanisms that centre our upright posture, thus preventing falls, through a process that we call standing balance,” says Jean-Sebastien. “Since these posture-correcting mechanisms oppose motion, to begin moving from an upright stance requires either a temporary suppression or an abrupt reconfiguration of these mechanisms. Once movement is underway, posture-correcting mechanisms are reconfigured to maintain posture while moving.”

Sensory cues, like those provided by the vestibular system in the inner ear (which encodes head motion and orientation relative to the gravitational field), actively contribute to the posture-correcting mechanisms involved in maintaining standing balance. Because the vestibular system appears to influence posture only during periods when the body is actively engaged in balance control, KIN researches questioned whether monitoring vestibular involvement in posture-correcting mechanisms would clarify which of the two possibilities occurs between standing balance and movement: a temporary suppression or an abrupt reconfiguration of these mechanisms.

“We examined the continuity of the vestibular control of balance during transition between standing and walking, and during a simple weight transfer between feet during standing,” says Jean-Sebastien. “We applied a small electrical current to the mastoid processes behind the ears of healthy participants and recorded its effects on the forces generated on the feet (a proxy for whole-body balance responses evoked by the vestibular stimulus).”

They found that the body suppresses the vestibular control of balance prior to the initiation and cessation of walking and prior to a shift in loading of the feet while standing. This could have important implications for robotics and patient groups and these results could aid the development of control algorithms to enable robots to exhibit a more robust transition to and from movement. “These findings could also help us to understand disorders of transition in patients, such as the ‘freezing of gait’ that occurs in individuals with Parkinson disease,” says Jean-Sebastien.

The paper can be found through the eLife website.