Dendritic calcium activity precedes inspiratory bursts in preBotzinger complex neurons.
Medullary interneurons of the preBötzinger complex assemble excitatory networks that produce inspiratory-related neural rhythms, but the importance of somatodendritic conductances in rhythm generation is still incompletely understood. Synaptic input may cause Ca(2+) accumulation postsynaptically to evoke a Ca(2+)-activated inward current that contributes to inspiratory burst generation. We measured Ca(2+) transients by two-photon imaging dendrites while recording neuronal somata electrophysiologically. Dendritic Ca(2+) accumulation frequently precedes inspiratory bursts, particularly at recording sites 50-300 μm distal from the soma. Preinspiratory Ca(2+) transients occur in hotspots, not ubiquitously, in dendrites. Ca(2+) activity propagates orthodromically toward the soma (and antidromically to more distal regions of the dendrite) at rapid rates (300-700 μm/s). These high propagation rates suggest that dendritic Ca(2+) activates an inward current to electrotonically depolarize the soma, rather than propagate as a regenerative Ca(2+) wave. These data provide new evidence that respiratory rhythmogenesis may depend on dendritic burst-generating conductances activated in the context of network activity.
Department of Applied Science, McGlothlin-Street Hall, The College of William and Mary, Williamsburg, Virginia 23187, USA. cadeln@wm.edu
Christopher A
CA
Del Negro
John A
JA
Hayes
Jens C
JC
Rekling
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism*; D004594:Electrophysiology; D051379:Mice; D009474:Neurons / Q000502:physiology*; D012125:Respiratory Center / Q000502:physiology*
D002118:Calcium
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