Cortical synaptic circuitry develops rapidly in the second postnatal week, simultaneous with experience-dependent turnover of dendritic spines. To relate the emergence of sensory maps to synaptogenesis, we recorded synaptic potentials evoked by whisker deflection in layer 2/3 neurons from postnatal day (P) 12 to 20. At P12, synaptic responses were undetectable. Only 2 days later in life (P14), receptive fields had mature organization. Sensory deprivation, if initiated before P14, disrupted receptive field structure. In layer 4, responses and maps were already mature by P12 and insensitive to deprivation, implying that barrel cortex develops from layer 4 to layer 2/3. Thus, P12-14 is a critical period shared by layer 2/3 synapses and their spines, suggesting that spine plasticity is involved in the refinement of maps.
|Number of pages||11|
|State||Published - 2 Aug 2001|
Bibliographical noteFunding Information:
We thank Hollis Cline, Veronica Egger, Josh Huang, Ed Ruthazer, and Josh Trachtenberg for comments on the manuscript. This work was supported by grants from the Klingenstein, Pew, and Mathers Foundations, HFSP, and NIH (K.S.), and the Ministerio de Educacion y Ciencia in Spain (M.M.).