Overview on the structure, composition, function, development, and plasticity of hippocampal dendritic spines

Abstract

There has been an explosion of new information on the neurobiology of dendritic spines in synaptic signaling, integration, and plasticity. Novel imaging and analytical techniques have provided important new insights into dendritic spine structure and function. Results are accumulating across many disciplines, and a step toward consolidating some of this work has resulted in Dendritic Spines of the Hippocampus. Leaders in the field provide a discussion at the level of advanced undergraduates, with sufficient detail to be a contemporary resource for research scientists. Critical reviews are presented on topics ranging from spine structure, formation, and maintenance, to molecular composition, plasticity, and the role of spines in learning and memory. Dendritic Spines of the Hippocampus provides a timely discussion of our current understanding of form and function at these excitatory synapses. We asked authors to include areas of controversy in their papers so as to distinguish results that are generally agreed upon from those where multiple interpretations are possible. We thank the contributors for their insights and thoughtful discussions. In this paper we provide background on the structure, composition, function, development, plasticity, and pathology of hippocampal dendritic spines. In addition, we highlight where each of these subjects will be elaborated upon in subsequent papers of this special issue of Hippocampus. Hippocampus 2000;10:501–511. © 2000 Wiley‐Liss, Inc.

Early continuous inhibition of group 1 mGlu signaling partially rescues dendritic spine abnormalities in the Fmr1 knockout mouse model for fragile X syndrome

“…The abnormal features of dendritic spines were also found in an unknown mental retardation (Purpura 1974) and autism (Carlisle and Kennedy 2005;Kaufmann and Moser 2000). Dendritic spines, the postsynaptic structures of most synapses, are believed to increase the connectivity of neurons and participate in neural computation (Sorra and Harris 2000;Yuste and Bonhoeffer 2001). Dynamic changes in the spines are thus involved in many fundamental processes such as learning, recall, and emotional behaviors (Harris 1999;Yuste and Bonhoeffer 2001).…”

Modeling the role of lateral membrane diffusion in AMPA receptor trafficking along a spiny dendrite

“…1. There are typically thousands of spines distributed along a single dendrite and a single spine has a size of around 1 μm, which is several orders of magnitude smaller than L (Sorra and Harris 2000). Therefore, we represent the population of spines in terms of a continuous density (number of spines per unit surface area) ρ(x), 0 ≤ x ≤ L, where x denotes axial distance along the dendrite from the soma.…”

“…In Fig. 3 we plot examples of steady-state receptor distributions for a dendritic cable of length L = 1 mm and circumference l = 1 μm, containing N = 1,000 identical spines distributed uniformly along the cable with density ρ 0 = 1 μm −2 (Sorra and Harris 2000). The baseline values for the various kinetic parameters shown in Fig.…”

“…Using L n = 0.45 μm and r n = 0.075 μm (Sorra and Harris 2000) and D n = 6.7 × 10 −3 μm 2 s −1 (Ashby et al 2006), we find that ≈ 7 × 10 −3 μm 2 s −1 , which is consistent with the baseline value shown in Table 1.…”

“…This is motivated by the observation that the spine neck, which forms the junction between a synapse and its parent dendrite, varies in radius from ∼ 0.02− 0.2 μm, which is typically an order of magnitude smaller than the spacing between spines (∼0.1-1 μm) and the circumference of the dendritic cable (∼1 μm), see Sorra and Harris (2000). In other words, the disc-like region or hole forming the junction between a spine and the dendritic cable is relatively small, and can therefore be neglected in a one-dimensional cable model.…”