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J Neurophysiol. 2014 Dec 15;112(12):3033-45. doi: 10.1152/jn.00349.2014. Epub 2014 Sep 3.

Relationship between individual neuron and network spontaneous activity in developing mouse cortex.

Author information

  • 1Department of Physiology and Biophysics, University of Washington, Seattle, Washington;
  • 2Center for Brain Science, Harvard University, Cambridge, Massachusetts;
  • 3Undergraduate Neurobiology Program, University of Washington, Seattle, Washington; and.
  • 4Department of Bioengineering, University of Washington, Seattle, Washington; Undergraduate Neurobiology Program, University of Washington, Seattle, Washington; and.
  • 5Department of Physiology and Biophysics, University of Washington, Seattle, Washington; UW Institute for Neuroengineering, University of Washington, Seattle, Washington.
  • 6Department of Biology, University of Washington, Seattle, Washington; profbill@u.washington.edu.

Abstract

Spontaneous synchronous activity (SSA) that propagates as electrical waves is found in numerous central nervous system structures and is critical for normal development, but the mechanisms of generation of such activity are not clear. In previous work, we showed that the ventrolateral piriform cortex is uniquely able to initiate SSA in contrast to the dorsal neocortex, which participates in, but does not initiate, SSA (Lischalk JW, Easton CR, Moody WJ. Dev Neurobiol 69: 407-414, 2009). In this study, we used Ca(2+) imaging of cultured embryonic day 18 to postnatal day 2 coronal slices (embryonic day 17 + 1-4 days in culture) of the mouse cortex to investigate the different activity patterns of individual neurons in these regions. In the piriform cortex where SSA is initiated, a higher proportion of neurons was active asynchronously between waves, and a larger number of groups of coactive cells was present compared with the dorsal cortex. When we applied GABA and glutamate synaptic antagonists, asynchronous activity and cellular clusters remained, while synchronous activity was eliminated, indicating that asynchronous activity is a result of cell-intrinsic properties that differ between these regions. To test the hypothesis that higher levels of cell-autonomous activity in the piriform cortex underlie its ability to initiate waves, we constructed a conductance-based network model in which three layers differed only in the proportion of neurons able to intrinsically generate bursting behavior. Simulations using this model demonstrated that a gradient of intrinsic excitability was sufficient to produce directionally propagating waves that replicated key experimental features, indicating that the higher level of cell-intrinsic activity in the piriform cortex may provide a substrate for SSA generation.

KEYWORDS:

activity-dependent development; cortex; piriform cortex; spontaneous activity

PMID:
25185811
PMCID:
PMC4269705
DOI:
10.1152/jn.00349.2014
[PubMed - indexed for MEDLINE]
Free PMC Article
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