Initiation, Labile, and Stabilization Phases of Experience-Dependent Plasticity at Neocortical Synapses

Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.75). 05/2013; 33(19):8483-93. DOI: 10.1523/JNEUROSCI.3575-12.2013
Source: PubMed

ABSTRACT Alteration of sensory input can change the strength of neocortical synapses. Selective activation of a subset of whiskers is sufficient to potentiate layer 4-layer 2/3 excitatory synapses in the mouse somatosensory (barrel) cortex, a process that is NMDAR dependent. By analyzing the time course of sensory-induced synaptic change, we have identified three distinct phases for synaptic strengthening in vivo. After an early, NMDAR-dependent phase where selective whisker activation is rapidly translated into increased synaptic strength, we identify a second phase where this potentiation is profoundly reduced by an input-specific, NMDAR-dependent depression. This labile phase is transient, lasting only a few hours, and may require ongoing sensory input for synaptic weakening. Residual synaptic strength is maintained in a third phase, the stabilization phase, which requires mGluR5 signaling. Identification of these three phases will facilitate a molecular dissection of the pathways that regulate synaptic lability and stabilization, and suggest potential approaches to modulate learning.

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