Functional synaptic connections among respiratory neurons

This presentation focuses on the application of methods to determine functi onal connections between neurons in the respiratory network of adult decere brate rats. We employ a general network investigation paradigm that first e xamines the intracellular recordings of a respiratory neuron and then deter mines which neurons synapse with it to produce the observed membrane potent ial changes. It is used to pursue the source of respiratory excitation and inhibition from its arrival at phrenic motoneurons to respiratory neurons i n the medulla, and then examine some of the interactions among these neuron s that shape their patterns of activity. Findings include a demonstration t hat phrenic motoneuron activity is determined by excitation from medullary inspiratory premotor neurons and inhibition by Botzinger complex expiratory neurons, and that the latter neurons inhibit both medullary inspiratory pr emotor neurons and themselves. We conclude that these functional interconne ctions explain the activity patterns of some respiratory neurons, but the c onnections between neurons thought to be involved in rhythm generation rema in to be demonstrated in adult rats. (C) 2000 Elsevier Science B.V. All rig hts reserved.