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Neuron. 2016 Feb 17;89(4):756-69. doi: 10.1016/j.neuron.2016.01.010. Epub 2016 Feb 4.

Inhibitory Synapses Are Repeatedly Assembled and Removed at Persistent Sites In Vivo.

Author information

1
Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
2
Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
3
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
4
Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
5
Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA; Max Planck Institute of Neurobiology, Martinsried 82152, Germany.
6
Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki 444-8585, Japan; Department of Physiological Science, Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan; JST, CREST, Tokyo 102-0076, Japan.
7
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
8
Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Electronic address: nedivi@mit.edu.

Abstract

Older concepts of a hard-wired adult brain have been overturned in recent years by in vivo imaging studies revealing synaptic remodeling, now thought to mediate rearrangements in microcircuit connectivity. Using three-color labeling and spectrally resolved two-photon microscopy, we monitor in parallel the daily structural dynamics (assembly or removal) of excitatory and inhibitory postsynaptic sites on the same neurons in mouse visual cortex in vivo. We find that dynamic inhibitory synapses often disappear and reappear again in the same location. The starkest contrast between excitatory and inhibitory synapse dynamics is on dually innervated spines, where inhibitory synapses frequently recur while excitatory synapses are stable. Monocular deprivation, a model of sensory input-dependent plasticity, shortens inhibitory synapse lifetimes and lengthens intervals to recurrence, resulting in a new dynamic state with reduced inhibitory synaptic presence. Reversible structural dynamics indicate a fundamentally new role for inhibitory synaptic remodeling--flexible, input-specific modulation of stable excitatory connections.

PMID:
26853302
PMCID:
PMC4760889
DOI:
10.1016/j.neuron.2016.01.010
[Indexed for MEDLINE]
Free PMC Article

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