Muscles and their neural control

The session on 'The Muscles and Their Neural Control' comprised papers that covered an extremely broad field, ranging from single membrane channels to integration at the motor unit level. To start with the molecular mechanisms, slow noninactivating sodium channels were postulated to be the common denominator in a number of myopathies, their activation causing depolarization and thus muscle weakness. New ideas were presented regarding muscle insulin receptors as the main target for neurotrophic influences, as well as transmitter release at nonmammalian motor nerve terminals. Changes in muscle compliance seem to be involved in adaptation of spindle sensitivity and reflex activity. Also, data were presented in favor of a neurotoxic component in myotrophic lateral sclerosis. Analysis of stationary motor unit discharges can differentiate parkinsonian patients without tremor from normal controls. Long-term use-dependent factors that change muscle properties have considerable effects on the way in which contractile force is graded.