Modification of Oscillator Function by Electrical Coupling to Nonoscillatory Neurons

Abstract

Neurons with intrinsic oscillatory properties are known to be present in all nervous systems studied to date. Indeed, it is now clear that many neurons not only fire rapid action potentials, either spontaneously or in response to synaptic inputs or sensory stimuli, but also display slowly varying voltageand time-dependent conductances that allow them to burst rhythmically or to generate slow plateau potentials (Llinás, 1988; Jacklet, 1989). Induced rhythms have been defined in this volume (see introductory chapter) as oscillations that are triggered or altered by an external influence that itself is not necessarily oscillatory. Despite our growing realization that oscillatory processes and slowly activating and/or inactivating voltage-dependent processes are likely to play critical roles in the generation of rhythmic motor activity, as well as in higher order sensory processes, remarkably little is known about the ways in which networks that contain oscillatory elements function. Likewise, little is understood concerning how network interactions modulate the properties of their oscillatory elements. In this chapter we review some recent experimental studies in the stomatogastric nervous system of crustaceans as well as some theoretical studies motivated by these experimental findings that shed light on how neurons that are electrically coupled to oscillatory neurons can shape the frequency and waveform of the oscillations.