Synapse-specific downregulation of NMDA receptors by early experience: a critical period for plasticity of sensory input to olfactory cortex.
Olfaction is required at birth for survival; however, little is known about the maturation of olfactory cortical circuits. Here we show that in vivo sensory experience mediates the development of excitatory transmission in pyramidal neurons of rat olfactory cortex. We find a postnatal critical period during which there is an experience-dependent increase in the contribution of AMPARs versus NMDARs to transmission at primary sensory synapses but not associational inputs. The shift in receptors underlying transmission is mediated by a strong activity-dependent downregulation of NMDARs and modest increase in AMPARs. Sensory activity leads to a loss of "silent" NMDAR-only synapses and an increase in threshold for inducing long-term plasticity. These results indicate the importance of early olfactory experience in the establishment of cortical circuits and could reflect mechanisms governing early olfactory "imprinting."
Franks
Kevin M
KM
Department of Neuroscience, University of California, San Diego School of Medicine, La Jolla, CA 92093, USA.
Isaacson
Jeffry S
JS
D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D015536:Down-Regulation / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D017774:Long-Term Potentiation / Q000502:physiology; D009434:Neural Pathways / Q000254:growth & development / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D009833:Olfactory Pathways / Q000254:growth & development / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism / Q000502:physiology; D018080:Receptors, GABA-B / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology; D012903:Smell / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D018091:Receptors, AMPA; D018080:Receptors, GABA-B; D016194:Receptors, N-Methyl-D-Aspartate