Sun, 20 Jul 2008 13:46:45 BST CiteULike: lechristophe Honkura http://www.citeulike.org/user/lechristophe/author/Honkura CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/lechristophe/article/2669700 <i>Neuron, Vol. 57, No. 5. (13 March 2008), pp. 719-729.</i><br /><br />Summary Synapse function and plasticity depend on the physical structure of dendritic spines as determined by the actin cytoskeleton. We have investigated the organization of filamentous (F-) actin within individual spines on CA1 pyramidal neurons in rat hippocampal slices. Using two-photon photoactivation of green fluorescent protein fused to [beta]-actin, we found that a dynamic pool of F-actin at the tip of the spine quickly treadmilled to generate an expansive force. The size of a stable F-actin pool at the base of the spine depended on spine volume. Repeated two-photon uncaging of glutamate formed a third pool of F-actin and enlarged the spine. The spine often released this "enlargement pool" into the dendritic shaft, but the pool had to be physically confined by a spine neck for the enlargement to be long-lasting. Ca2+/calmodulin-dependent protein kinase II regulated this confinement. Thus, spines have an elaborate mechanical nature that is regulated by actin fibers. The Subspine Organization of Actin Fibers Regulates the Structure and Plasticity of Dendritic Spines Naoki Honkura Masanori Matsuzaki Jun Noguchi Graham Ellis-Davies Haruo Kasai doi:10.1016/j.neuron.2008.01.013 Neuron, Vol. 57, No. 5. (13 March 2008), pp. 719-729. 2008-04-14T16:24:42-00:00 2008 Neuron 57 5 719 729 actin cytosqueleton dendritic_spines photoactivation