title: Experience-dependent switch in sign and mechanisms for plasticity in layer 4 of primary visual cortex.
abstract: Neural circuits are extensively refined by sensory experience during postnatal development. How the maturation of recurrent cortical synapses may contribute to events regulating the postnatal refinement of neocortical microcircuits remains controversial. Here we show that, in the main input layer of rat primary visual cortex, layer 4 (L4), recurrent excitatory synapses are endowed with multiple, developmentally regulated mechanisms for induction and expression of excitatory synaptic plasticity. Maturation of L4 synapses and visual experience lead to a sharp switch in sign and mechanisms for plasticity at recurrent excitatory synapses in L4 at the onset of the critical period for visual cortical plasticity. The state of maturation of excitatory pyramidal neurons allows neurons to engage different mechanisms for plasticity in response to the same induction paradigm. Experience is determinant for the maturation of L4 synapses, as well as for the transition between forms of plasticity and the mechanisms they may engage. These results indicate a tight correlation between the effects of sensory drive and maturation on cortical neurons and provide a new set of cellular mechanisms engaged in the postnatal refinement of cortical circuits.
authors.affiliation: Department of Neurobiology and Behavior and SUNY Eye Institute, State University of New York-Stony Brook, Stony Brook, New York 11794, USA.
authors.forename: Lang
authors.initials: L
authors.lastname: Wang
authors.forename: Alfredo
authors.initials: A
authors.lastname: Fontanini
authors.forename: Arianna
authors.initials: A
authors.lastname: Maffei
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001703:Biophysics; D003423:Critical Period, Psychological; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D012683:Sensory Deprivation / Q000502:physiology*; D055366:Synaptic Potentials / Q000187:drug effects; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D014793:Visual Cortex / Q000166:cytology* / Q000254:growth & development / Q000502:physiology
chemical_list: D018691:Excitatory Amino Acid Antagonists; C474696:methyl-(4-carboxyphenyl)glycine; C056639:2-amino-5-phosphopentanoic acid; D014633:Valine; D005998:Glycine