Developmental maturation of excitation and inhibition balance in principal neurons across four layers of somatosensory cortex

Z. Zhang, Y. Y. Jiao, Q. Q. Sun

Research output: Contribution to journalArticle

Abstract

In adult cortices, the ratio of excitatory and inhibitory conductances (E/I ratio) is presumably balanced across a wide range of stimulus conditions. However, it is unknown how the E/I ratio is postnatally regulated, when the strength of synapses are rapidly changing. Yet, understanding of such a process is critically important, because there are numerous neuropsychological disorders, such as autism, epilepsy and schizophrenia, associated with disturbed E/I balances. Here we directly measured the E/I ratio underlying locally induced synaptic conductances in principal neurons from postnatal day 8 (P8) through 60. We found that (1) within each developmental period, the E/I ratio across four major cortical layers was maintained at a similar value under wide range of stimulation intensities; and (2) there was a rapid developmental decrease in the E/I ratio, which occurred within a sensitive period between P8 to P18 with exception of layer II/III. By comparing the excitatory and inhibitory conductances, as well as key synaptic protein expressions, we found a net increase in the number and strength of inhibitory, but not excitatory synapses, is responsible for the developmental decrease in the E/I ratio in the barrel cortex. The inhibitory markers were intrinsically co-regulated, gave rise to a sharp increase in the inhibitory conductance from P8 to P18. These results suggest that the tightly regulated E/I ratios in adults cortex is a result of drastic changes in relative weight of inhibitory but not excitatory synapses during critical period, and the local inhibitory structural changes are the underpinning of altered E/I ratio across postnatal development.

Original languageEnglish (US)
Pages (from-to)10-25
Number of pages16
JournalNeuroscience
Volume174
DOIs
StatePublished - Feb 3 2011

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Keywords

  • Critical period
  • E/I balance
  • Neocortex
  • Postnatal development
  • Synaptic conductance

ASJC Scopus subject areas

  • Neuroscience(all)

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