Distinguished Speaker: Eric J. Perreault, PhD, Northwestern University
Title: Regulation of shoulder stability: neural mechanisms that reflect and augment our anatomy
Abstract: The neural and musculoskeletal systems are intimately linked in the control of movement and posture. The musculoskeletal system serves as a mechanical interface between the computations of our nervous system and our ability to physically interact with the world around us. Our laboratory works at the intersection of biomechanics and motor systems neuroscience. Our engineering focus is on developing tools to noninvasively quantify the mechanisms underlying the neural control of limb mechanics, and our scientific focus in on using those tools to better understand neuromechanical control in healthy and impaired populations. This talk will review two recent studies: investigations into the use of ultrasound shear wave elastography for quantifying the mechanical properties of individual muscles, and studies on the neural and biomechanical factors contributing to the regulation of shoulder stability.
The shoulder is the most complex and mobile joint in the human body, but this mobility comes at a cost as it is also the joint most likely to dislocate. Appropriately regulating the mechanical properties of the shoulder therefore is critical for maintaining stability and controlling motion of the upper limb during activities of daily living. We have been conducting experiments to quantify the neural and biomechanical factors contributing to the 3D mechanics of the human shoulder. These have demonstrated global increases in shoulder impedance during the generation of even single degree-of-freedom isometric torques. This broad mechanical coupling is reinforced by distributed feedback control in which the stretch-sensitive reflexes to any given muscle exhibit complex patterns of gain-scaling that imply contributions from multiple muscles acting about the shoulder. Finally, we have recently been exploring the limits of neural control, demonstrating that the ability to regulate shoulder stiffness decreases in postures where dislocations are most likely to occur.
Bio: Eric Perreault is Professor and Chair of Biomedical Engineering at Northwestern University, with joint appointments in the Department of Physical Medicine and Rehabilitation, and at the Shirley Ryan AbilityLab. He received his B.Eng. and M. Eng. degrees in Electrical Engineering from McGill University and his PhD in Biomedical Engineering from Case Western Reserve University. Eric’s research focuses on understanding the neural and biomechanical factors involved in the control of multi-joint movement and posture and how these factors are modified following neuromotor pathologies such as stroke and spinal cord injury. The goal is to provide a scientific basis for understanding normal and pathological motor control that can be used to guide rehabilitative strategies for individuals with motor deficits.