title: Ongoing in vivo experience triggers synaptic metaplasticity in the neocortex.
abstract: In vivo experience can occlude subsequent induction of long-term potentiation and enhance long-term depression of synaptic responses. Although a reduced capacity for synaptic strengthening may function to prevent excessive excitation, such an effect paradoxically implies that continued experience or training should not improve and may even degrade neural representations. In mice, we examined the effect of ongoing whisker stimulation on synaptic strengthening at layer 4-2/3 synapses in the barrel cortex. Although N-methyl-d-aspartate receptors were required to initiate strengthening, they subsequently suppressed further potentiation at these synapses in vitro and in vivo. Despite this transition, synaptic strengthening continued with additional sensory activity but instead required the activation of metabotropic glutamate receptors, suggesting a mechanism by which continued experience can result in increasing synaptic strength over time.
authors.affiliation: Department of Biological Sciences and Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
authors.forename: Roger L
authors.initials: RL
authors.lastname: Clem
authors.forename: Tansu
authors.initials: T
authors.lastname: Celikel
authors.forename: Alison L
authors.initials: AL
authors.lastname: Barth
mesh_terms: D000818:Animals; D001245:Association Learning; D002118:Calcium / Q000378:metabolism; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials; D017774:Long-Term Potentiation; D036881:Long-Term Synaptic Depression; D051379:Mice; D008822:Mice, Transgenic; D019579:Neocortex / Q000502:physiology*; D009473:Neuronal Plasticity; D009474:Neurons / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000737:chemistry; D015398:Signal Transduction; D013003:Somatosensory Cortex / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation* / Q000502:physiology
chemical_list: D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D002118:Calcium