Research

Some nice images related to our research:

Stability of PSD-95 clusters in the intact mouse neocortex. A sparse subpopulation of layer 2/3 neurons expressed a red cytoplasmic protein (mCherry1) and PSD-95 fused to a green fluorescent protein (GFP). Left, overview of a dendritic branch. Right, time-lapse imaging of a region of interest (white box in the left image). The relatively stable sizes of the green spots indicate stable relative synapse sizes.
Noah Gray, Robby Weimer, and Karel Svoboda

Two-photon fluorescence lifetime microscopy of Ras activation in single dendritic spines in brain slices. A: The imaged neuron expresses a genetically encoded Ras sensor based on GFP (green fluorescent protein) and mRFP1 (monomeric red fluorescent protein). The fluorescence lifetime of the GFP decreases with Ras activation. Color indicates fluorescence lifetime. At t = 0, glutamate was uncaged next to the spine marked by the arrowhead. In response, Ras activity increased locally and the spine grew in volume. B: Ras activity increased over 10 mm of dendritic length. C: Changes in spine volume in selected regions of interest were specific to a synapse.
Ryohei Yasuda and Karel Svoboda

Synaptic input map for a layer 2/3 neuron in the barrel cortex (colored background). Overlaid is the morpholoy of the neuron (blue) and electrophysiological traces from which the synaptic input map was constructed (black). A schematic circuit diagram is also shown (white).
From the Svoboda lab. For details, see Shepherd, G.M., Pologruto, T.A., and Svoboda, K. 2003. Neuron 38:277–289.

Experience-dependent synaptic plasticity in the adult neocortex in vivo. Left, images collected 24 hours apart. Note stable (yellow arrow) and transient (blue and red arrows) spines. Scale bar, 5 mm.
Right, electron micrograph of new spine, indicating that it participates in synaptic transmission. Scale bar, 0.125 mm.
From Trachtenberg, J.T., Chen, B.E., Knott, G.W., Feng, G., Sanes, J.R., Welker, E., and Svoboda, K. 2002. Nature 420:788–794. © 2002 Nature Publishing Group.

Experience-dependent spine plasticity in barrel cortex in vivo. Three images collected 45 minutes apart were color coded and overlaid. White regions indicate stable dendritic segments. Green (red) spines retracted (sprouted) during the observation period.
Photo: Karel Svoboda