Gerald E. Loeb - US grants

The hindlimb has long been the chief system in which the motor sequencing and control functions of the spinal cord have been studied. Recent work has emphasized the mechanical complexity of the musculoskeletal apparatus and the corresponding complexity of spinal circuits for sensory feedback and reflexes; however, there has been no formal approach to relate the two. Furthermore, the need for systematic application of control theory has been underlined by recent clinical work to restore motor control of paralyzed limbs via functional neuromuscular stimulation and other prosthetic acids. This proposal seeks funds to: 1) continue the development of a 2D mathematical model of the musculoskeletal apparatus and make it available as a personal computer program and as a monograph describing the functional anatomical and biomechanical relationships of the cat hindlimb during normal walking. 2) apply linear quadratic regulator theory to make quantitative predictions of the distribution of proprioceptive feedback from muscles and joints under different kinematic conditions and behavioral objectives of the organism. 3) generalize the modeling process by using automatic equation writing techniques to permit users to generate models of arbitrary physical form, including 3D and multi-legged representations, interactively. Data on the natural EMG and kinesiology from chronically instrumented animal will be combined with musculoskeletal morphometry to permit the step cycle to be decomposed into joint torques (by inverse dynamics) and the work of individual muscles (using an experimentally validated model of EMG- to-force-output). Hypothetical sets of proprioceptors with properties akin to those recorded previously from chronically instrumented animals will be built into a model of the sensory feedback available for responding to small perturbations. Linear quadratic controllers will be designed for a range of optimization criteria that weight energy conservation vs. various measures of kinesiological stability. These feedback matrices and the responses of the model system to applied perturbations will be compared wit the responses to electrical stimulation of muscle nerves (to be measured during treadmill walking in chronically instrumented cats) and with data from other investigators regarding responses to mechanical perturbations of standing posture and projections from proprioceptors via spinal cord circuits.

[unreadable] DESCRIPTION (provided by applicant): In theory, a wide range of sensory and motor dysfunctions can be treated by electrical stimulation to evoke patterns of neural activity similar to those that underlie normal function. In practice, however, such stimulation typically has required relatively expensive and large devices implanted by a surgeon or skin surface stimulation applied by a trained therapist. We have developed a new class of generic devices that can deliver precisely metered stimulation pulses to an arbitrary number of nerve and muscle sites. These leadless BIOnic Neurons (BlONsTM) can be injected through a 12 gauge hypodermic needle into the desired locations. They receive their power and digital command signals by RF telemetry from a single, externally worn transmission coil. They have been used extensively in preclinical animal studies of the effects of electrically induced muscle exercise. A clinical trial for shoulder subluxation began in November, 1999, and a second for osteoarthritis of the knee began in June 2000, both with excellent results to date. Under this BRP, we will design and build BION1 implants and accessory components for testing, programming and controlling them in patients. We will develop and test a range of clinical applications to determine safety and efficacy and to understand further the mechanisms underlying neuromuscular pathology and treatment. In the first five years, these applications include activating and strengthening muscles in the hand, shoulder, and ankle in patients suffering from stroke and cerebral palsy. Enhancements of the current BION1 technology are under development (with separate NIH funding) to improve power efficiency and portability and to incorporate sensing and back-telemetry for functional electrical stimulation (FES). In subsequent years, we will expand the clinical applications to provide more complete rehabilitation of multijoint dysfunctions that commonly occur in these disorders and we will incorporate advanced BION2 technology to provide functional reanimation of paralyzed limbs using neural prosthetic control.

0922784
Loeb

This proposed MRI instrument will provide a highly flexible testbed for diverse research activities in the general field of robotic and prosthetic haptic. Robots have had a huge economic impact on certain types of industrial productivity in repetitive and/or hazardous environments but they are currently unable to handle common objects or tools. Providing robotic manipulation with haptic capabilities similar to humans would greatly extend the range of applications and environments in which they could be used.
There are three major aspects of the development project: i) Design and production of TAC modules; ii) Procurement of and interface with commercial mechatronic hand plus arm; iii) Development of software modules for compliant exploratory behaviors, processing of sensory data and extraction of information about external objects.

The proposed instrument represents a fusion of recent advances in biomimetic principles of sensory transduction, haptic exploration and compliant control.