Protracted synaptogenesis after activity-dependent spinogenesis in hippocampal neurons
Journal of Neuroscience. 2007-07-25; 27(30): 8149-8156
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1. J Neurosci. 2007 Jul 25;27(30):8149-56.
Protracted synaptogenesis after activity-dependent spinogenesis in hippocampal
Nägerl UV(1), Köstinger G, Anderson JC, Martin KA, Bonhoeffer T.
(1)Max Planck Institute of Neurobiology, 82152 München-Martinsried, Germany.
Activity-dependent morphological plasticity of neurons is central to
understanding how the synaptic network of the CNS becomes reconfigured in
response to experience. In recent years, several studies have shown that synaptic
activation that leads to the induction of long-term potentiation also drives the
growth of new dendritic spines, raising the possibility that new synapses are
made. We examine this directly by correlating time-lapse two-photon microscopy of
newly formed spines on CA1 pyramidal neurons in organotypic hippocampal slices
with electron microscopy. Our results show that, whereas spines that are only a
few hours old rarely form synapses, older spines, ranging from 15 to 19 h,
consistently have ultrastructural hallmarks typical of synapses. This is in
agreement with a recent in vivo study that showed that, after a few days, new
spines consistently form functional synapses. In addition, our study provides a
much more detailed understanding of the first few hours after activity-dependent
spinogenesis. Within tens of minutes, physical contacts are formed with existing
presynaptic boutons, which slowly, over the course of many hours, mature into new
PMID: 17652605 [Indexed for MEDLINE]