Posture-dependent control of stimulation in standing neuroprosthesis: simulation feasibility study.

We used a three-dimensional biomechanical model of human standing to test the feasibility of feed-forward control systems that vary stimulation to paralyzed muscles based on the user's posture and desire to effect a postural change. The controllers examined were (1) constant baseline stimulation, which represented muscle activation required to maintain erect standing, and (2) posture follower, which varied muscle activation as a function of the location of the projection of whole-body center of mass on the base of support. Posture-dependent control of stimulation demonstrated significant benefits over open-loop stimulation.

Posture shifting after spinal cord injury using functional neuromuscular stimulation--a computer simulation study.

The ability for individuals with spinal cord injury (SCI) to affect changes in standing posture with functional neuromuscular stimulation (FNS) was explored using an anatomically inspired musculoskeletal model of the trunk, pelvis and lower extremities (LE). The model tracked trajectories for anteriorly and laterally shifting movements away from erect stance. Forces were applied to both shoulders to represent upper extremity (UE) interaction with an assistive device (e.

Selection of optimal muscle set for 16-channel standing neuroprosthesis.

The Case Western Reserve University/Department of Veterans Affairs 8-channel lower-limb neuroprosthesis can restore standing to selected individuals with paraplegia by application of functional electrical stimulation. The second generation of this system will include 16 channels of stimulation and a closed-loop control scheme to provide automatic postural corrections. This study used a musculoskeletal model of the legs and trunk to determine which muscles to target with the new system in order to maximize the range of postures that can be statically maintained, which should increase the system's ability to provide adequate support to maintain standing when the user's posture moves away from a neutral stance, either by an external disturbance or a volitional change in posture by the user.

Passive hinge forces in the feeding apparatus of Aplysia aid retraction during biting but not during swallowing.

Swallowing and biting responses in the marine mollusk Aplysia are both mediated by a cyclical alternation of protraction and retraction movements of the grasping structure, the radula and underlying odontophore, within the feeding apparatus of the animal, the buccal mass. In vivo observations demonstrate that Aplysia biting is associated with strong protractions and rapid initial retractions, whereas Aplysia swallowing is associated with weaker protractions and slower initial retractions. During biting, the musculature joining the radula/odontophore to the buccal mass (termed the "hinge") is stretched more than in swallowing.