Fig. 1

The structure of dendritic spines of hippocampal pyramidal neurons. Using particle-mediated gene transfer (a.k.a. gene gun), organotypic slice cultures were transfected with cDNA coding for eYFP. Top panels: Laser-scanning confocal microscopy images of a pyramidal neuron in area CA1 are shown at different magnifications to illustrate the complexity of their dendritic arbor and the abundance of dendritic spines in secondary and tertiary branches. Bottom left panel: A maximum-intensity projection of z-stacks shows a dendritic segment studded with the most common spine morphologies, i.e. stubby, mushroom and thin. The cartoon illustrates the geometrical dimensions measured in individual spines to categorize them (adapted from Ref. 32). Bottom right panel: A mushroom dendritic spine (outlined in green) forms an asymmetric synapse with a single presynaptic terminal (outlined in red) in stratum radiatum of area CA1 in organotypic slice culture