Chapter 9 Selectivity of Presynaptic Inhibition: a Mechanism for Independent Control of Information Flow through Individual Collaterals of Single Muscle Spindle Afferents

Abstract

This chapter discusses the observations on the concept of the intraspinal arborizations of afferent fibers that are not obligatory routes for the conduction of action potentials but are instead dynamic systems that can be modified by central mechanisms to restrict information to selected neuronal targets. The differential inhibition of primary afferent depolarization (PAD) is envisaged as a means by which different spinal postsynaptic targets coupled by sensory input from a common source could be decoupled by central control mechanisms. This could be of relevance for motor performance and sensory discrimination. The extent to which these changes are reflected at the population level depends on the degree of synchronization of the PAD-mediating interneurons, a feature that can also be centrally controlled. A more functional approach to the understanding of the central mechanisms involved in the pre-synaptic control of information flow in sensory fibers will require the use of noninvasive methods in behaving animals performing specific motor tasks.