title: Control of interneuron firing by subthreshold synaptic potentials in principal cells of the dorsal cochlear nucleus.
abstract: Voltage-gated ion channels amplify, compartmentalize, and normalize synaptic signals received by neurons. We show that voltage-gated channels activated during subthreshold glutamatergic synaptic potentials in a principal cell generate an excitatory→inhibitory synaptic sequence that excites electrically coupled interneurons. In fusiform cells of the dorsal cochlear nucleus, excitatory synapses activate a TTX-sensitive Na(+) conductance and deactivate a resting Ih conductance, leading to a striking reshaping of the synaptic potential. Subthreshold voltage changes resulting from activation/deactivation of these channels subsequently propagate through gap junctions, causing slow excitation followed by inhibition in GABAergic stellate interneurons. Gap-junction-mediated transmission of voltage-gated signals accounts for the majority of glutamatergic signaling to interneurons, such that subthreshold synaptic events from a single principal cell are sufficient to drive spikes in coupled interneurons. Thus, the interaction between a principal cell's synaptic and voltage-gated channels may determine the spike activity of networks without firing a single action potential.
authors.affiliation: Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR 97239, USA; Vollum Institute & Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR 97239, USA.
authors.forename: Pierre F
authors.initials: PF
authors.lastname: Apostolides
authors.affiliation: Vollum Institute & Oregon Hearing Research Center, Oregon Health & Science University, Portland, OR 97239, USA. Electronic address: trussell@ohsu.edu.
authors.forename: Laurence O
authors.initials: LO
authors.lastname: Trussell
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D017626:Cochlear Nucleus / Q000502:physiology*; D007395:Interneurons / Q000502:physiology; D051379:Mice; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D013569:Synapses / Q000502:physiology; D055366:Synaptic Potentials / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology