Synaptic Depression Influences Inspiratory-Expiratory Phase Transition in Dbx1 Interneurons of the preBötzinger Complex in Neonatal Mice.

Theories of breathing's neural origins have heretofore focused on intrinsically bursting "pacemaker" cells operating in conjunction with synaptic inhibition for phase transition and cycle timing. However, contemporary studies falsify an obligatory role for pacemaker-like neurons and synaptic inhibition, giving credence to burst-generating mechanisms based on recurrent excitation among glutamatergic interneurons of the respiratory kernel. Here, we investigated the role of short-term synaptic depression in inspiratory-expiratory phase transition. Until now, this role remained an untested prediction of mathematical models. The present data emphasize that synaptic properties of excitatory interneurons of the respiratory rhythmogenic kernel, derived from Dbx1-expressing precursors, may provide the core logic underlying the rhythm for breathing.