gms | German Medical Science

59th Annual Meeting of the German Society of Neurosurgery (DGNC)
3rd Joint Meeting with the Italian Neurosurgical Society (SINch)

German Society of Neurosurgery (DGNC)

1 - 4 June 2008, Würzburg

Long-term in-vivo imaging of structural plasticity in the neocortex

In-vivo-Darstellung der synaptischen Strukturplastizität im Neokortex

Meeting Abstract

  • corresponding author C. Stetter - Neurochirurgische Klinik, Universitätsklinikum Würzburg
  • M. Hirschberg - Rudof-Virchow-Zentrum, Würzburg
  • M. Heckmann - Carl-Ludwig-Institut für Physiologie, Universität Leipzig, Leipzig
  • S. Sigrist - Rudof-Virchow-Zentrum, Würzburg
  • A.-L. Sirén - Neurochirurgische Klinik, Universitätsklinikum Würzburg

Deutsche Gesellschaft für Neurochirurgie. Società Italiana di Neurochirurgia. 59. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), 3. Joint Meeting mit der Italienischen Gesellschaft für Neurochirurgie (SINch). Würzburg, 01.-04.06.2008. Düsseldorf: German Medical Science GMS Publishing House; 2008. DocP 118

The electronic version of this article is the complete one and can be found online at:

Published: May 30, 2008

© 2008 Stetter et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Structural plasticity with synapse formation and elimination is a key component of memory capacity and may be critical for functional recovery upon brain injury. The aim of this study was to establish a method for long-term repeated in vivo imaging to of synaptic structural plasticity in the mouse neocortex.

Methods: Transgenic Thy1-YFP(H) mice expressing yellow-fluorescent protein (YFP) in layer-5 pyramidal neurons were anesthetized with ketamine-xylazine and equipped for in vivo imaging of dendritic spines in the parietal cortex either with an open-skull glass or thinned skull window. After a recovery period of 14 days, 4-6 weekly imaging sessions of 45-60 min in duration were started. For each session, mice were anesthetized with ketamine-xylazine. To reduce respiration-induced movement artifacts, the skull was glued to a stainless steel plate fixed to metal base. The animal was set under a two-photon microscope with multifocal scanhead splitter (TriMScope, LaVision BioTec) and the Ti-sapphire laser was tuned to the optimal excitation wavelength for YFP (890 nm). Images were acquired by using a 20x, 0.95 NA water-immersion objective (Olympus) in imaging depth of 100-200µm from the pial surface. Two-dimensional projections of three-dimensional image stacks containing dendritic segments of interest were saved for further analysis. At the end of the last imaging session, the mice were decapitated and the brain removed for histological analysis.

Results: Repeated in vivo imaging of dendritic spines of the layer-5 pyramidal neurons was successful using both open-skull glass and thinned skull windows. Both window techniques were associated with low phototoxicity after repeated sessions of imaging. Expression of the astrocytic marker GFAP and microglial activity marker IBA-1 in the cortex under the open-skull glass window was slightly increased as compared to that seen on the contralateral side 6 weeks after surgery.

Conclusions: Repeated imaging of dendritic spines in vivo allows monitoring of long-term structural dynamics of synapses. When carefully controlled for influence of repeated anaesthesia and phototoxicity, the method will be suitable to study changes in synaptic structural plasticity after brain injury.