ABSTRACT
BACKGROUND: We control the movements of our body and limbs through our muscles. However, the forces produced by our muscles depend unpredictably on the commands sent to them. This uncertainty has two sources: irreducible noise in the motor system's processes (i.e., motor noise) and variability in the relationship between muscle commands and muscle outputs (i.e., model uncertainty). Any controller, neural or artificial, benefits from estimating these uncertainties when choosing commands. METHODS: To examine these benefits, we used an experimental preparation of the rat hindlimb to electrically stimulate muscles and measure the resulting isometric forces. We compare a functional electric stimulation (FES) controller that represents and compensates for uncertainty in muscle forces with a standard FES controller that neglects uncertainty. RESULTS: Accounting for uncertainty substantially increased the precision of force control. CONCLUSION: Our study demonstrates the theoretical and practical benefits of representing muscle uncertainty when computing muscle commands. SIGNIFICANCE: The findings are relevant beyond FES as they highlight the benefits of estimating statistical properties of muscles for both artificial controllers and the nervous system.
Subject(s)
Computational Biology/methods , Electric Stimulation , Models, Biological , Muscle, Skeletal/physiology , Uncertainty , Animals , Computer Simulation , Female , Hindlimb/physiology , Models, Statistical , Rats , Rats, Sprague-DawleyABSTRACT
The purpose of this study was to compare the prevalence of ear, nose and particularly voice problems in groups of children with cleft palate (CP) and with unilateral cleft lip, alveolus and palate (UCLP). On the basis of history, regular otorhinolaryngological examinations and hearing tests, the prevalence of different pathologies was assessed in 80 CP children (35 boys and 45 girls) and 73 UCLP children (47 boys and 26 girls). Ear pathology was reported in 53.8 per cent of CP children and in 58.9 per cent of UCLP children. Nasal breathing was impaired in 14 CP (17.5 per cent) and 36 UCLP (49.3 per cent) children. Dysphonia was detected in 12.5 per cent of CP and 12.3 per cent of UCLP children. In 9.2 per cent of all cleft children, functional voice disorder caused a hoarse voice. Two-thirds of cleft children with functional dysphonia had protracted hearing loss. Therefore, ENT specialists must take an active role early in the treatment of children with clefts.
