Active dendritic conductances dynamically regulate GABA release from thalamic interneurons.
Inhibitory interneurons in the dorsal lateral geniculate nucleus (dLGN) process visual information by precisely controlling spike timing and by refining the receptive fields of thalamocortical (TC) neurons. Previous studies indicate that dLGN interneurons inhibit TC neurons by releasing GABA from both axons and dendrites. However, the mechanisms controlling GABA release are poorly understood. Here, using simultaneous whole-cell recordings from interneurons and TC neurons and two-photon calcium imaging, we find that synchronous activation of multiple retinal ganglion cells (RGCs) triggers sodium spikes that propagate throughout interneuron axons and dendrites, and calcium spikes that invade dendrites but not axons. These distinct modes of interneuron firing can trigger both a rapid and a sustained component of inhibition onto TC neurons. Our studies suggest that active conductances make LGN interneurons flexible circuit-elements that can shift their spatial and temporal properties of GABA release in response to coincident activation of functionally related subsets of RGCs.
Acuna-Goycolea
Claudio
C
Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
Brenowitz
Stephan D
SD
Regehr
Wade G
WG
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D003712:Dendrites / Q000502:physiology* / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation; D005829:Geniculate Bodies / Q000166:cytology*; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D007395:Interneurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D017711:Nonlinear Dynamics; D018408:Patch-Clamp Techniques; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D026941:Sodium Channel Blockers; D049452:Green Fluorescent Proteins; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D002118:Calcium