Analysis of spine morphological plasticity in developing hippocampal pyramidal neurons

Abstract

Dendritic spines are targets of most excitatory inputs in the central nervous system (CNS) and are morphologically heterogeneous. Ultrastructural studies have traditionally classified spines into four major categories (filopodia, stubby, thin, and mushroom) based on their distinct morphologies. The recent discovery of rapid morphological plasticity of spines has raised the possibility that those categories, rather than being intrinsically different populations of spines, represent instead temporal snapshots of a single dynamic phenomenon. We examined this question with two-photon time-lapse imaging of developing hippocampal pyramidal neurons, transfected with E-GFP in cultured slices. After blind scoring to morphologically classify spines into the four traditional groups, we analyzed the fate of populations of spines over a period of 2-4 h. We found considerable morphological conversions among all categories, although systematic trends were detected. While most stubbies and spines (defined for our analysis as the combination of thin and mushroom protrusions) retained their basic morphologies, most filopodia transformed into stubbies and spines, although they could also extend out of existing spines. Our results suggest that in developing hippocampal pyramidal neurons, traditional morphological distinctions are stable over short (<4 h) periods of time, but that at the same time, considerable mixing among these groups takes place.

High-ResolutionIn VivoImaging of Hippocampal Dendrites and Spines

“…We observed the complete range of spine morphologies described previously in vitro and in fixed preparations (Parnass et al, 2000;Sorra and Harris, 2000;Yuste and Bonhoeffer, 2004). Spine densities measured in vivo and in fixed tissue were indistinguishable (fixed tissue, 0.87 Ϯ 0.24 spines/m, n ϭ 346 spines; in vivo, 0.92 Ϯ 0.15 spines/m, n ϭ 225 spines; t test; p ϭ 0.51).…”

High-ResolutionIn VivoImaging of Hippocampal Dendrites and Spines

“…We observed the complete range of spine morphologies described previously in vitro and in fixed preparations (Parnass et al, 2000;Sorra and Harris, 2000;Yuste and Bonhoeffer, 2004). Spine densities measured in vivo and in fixed tissue were indistinguishable (fixed tissue, 0.87 Ϯ 0.24 spines/m, n ϭ 346 spines; in vivo, 0.92 Ϯ 0.15 spines/m, n ϭ 225 spines; t test; p ϭ 0.51).…”

Methamphetamine learning induces persistent nonmuscle myosin II-dependent spine motility in the basolateral amygdala

“…At P28-35, the pattern reversed, with BLA spines becoming more stable than those in CA1, making the impact of METH training on BLA motility at this age even more striking. In this series of experiments, we also confirmed that spine motility is actin-dependent in the BLA, as has been shown in cultured hippocampal cells and slices (35,37,39,45). This established that spine motility is an appropriate measure to determine the impact of METH on spine actin dynamics.…”

“…Because this was the first assessment of spine motility in the BLA, we first confirmed that motility rates decrease with age, as has been reported in cultured hippocampal cells and slices, dentate gyrus and CA1 acute slices, and primary visual cortex in vivo (34,35,(37)(38)(39)(40)45). This also allowed us to compare the rates of spine motility between the BLA and CA1 in early postnatal life and adolescence.…”

Calcium/Calmodulin-Dependent Protein Kinase II Alters Structural Plasticity and Cytoskeletal Dynamics inDrosophila

“…Molecular/genetic signaling determines this morphology and changing function by modulating microtubule-based dendritic shafts and actin-rich dendritic filopodia or spines (Fifkova and Delay, 1982;Matus et al, 1982;Micheva et al, 1998). Filopodia can serve multiple functions including acting as precursors to dendritic spines (Parnass et al, 2000) and pioneering the formation of dendritic arbors (Niell et al, 2004). Dendritic compartments undergo dynamic regulation and demonstrate both morphological and synaptic plasticity (Engert and Bonhoeffer, 1999;Maletic-Savatic et al, 1999;Toni et al, 1999;Yuste and Bonhoeffer, 2001).…”

High-ResolutionIn VivoImaging of Hippocampal Dendrites and Spines

“…We observed the complete range of spine morphologies described previously in vitro and in fixed preparations (Parnass et al, 2000;Sorra and Harris, 2000;Yuste and Bonhoeffer, 2004). Spine densities measured in vivo and in fixed tissue were indistinguishable (fixed tissue, 0.87 Ϯ 0.24 spines/m, n ϭ 346 spines; in vivo, 0.92 Ϯ 0.15 spines/m, n ϭ 225 spines; t test; p ϭ 0.51).…”

Methamphetamine learning induces persistent nonmuscle myosin II-dependent spine motility in the basolateral amygdala

“…At P28-35, the pattern reversed, with BLA spines becoming more stable than those in CA1, making the impact of METH training on BLA motility at this age even more striking. In this series of experiments, we also confirmed that spine motility is actin-dependent in the BLA, as has been shown in cultured hippocampal cells and slices (35,37,39,45). This established that spine motility is an appropriate measure to determine the impact of METH on spine actin dynamics.…”

“…Because this was the first assessment of spine motility in the BLA, we first confirmed that motility rates decrease with age, as has been reported in cultured hippocampal cells and slices, dentate gyrus and CA1 acute slices, and primary visual cortex in vivo (34,35,(37)(38)(39)(40)45). This also allowed us to compare the rates of spine motility between the BLA and CA1 in early postnatal life and adolescence.…”

Calcium/Calmodulin-Dependent Protein Kinase II Alters Structural Plasticity and Cytoskeletal Dynamics inDrosophila

“…Molecular/genetic signaling determines this morphology and changing function by modulating microtubule-based dendritic shafts and actin-rich dendritic filopodia or spines (Fifkova and Delay, 1982;Matus et al, 1982;Micheva et al, 1998). Filopodia can serve multiple functions including acting as precursors to dendritic spines (Parnass et al, 2000) and pioneering the formation of dendritic arbors (Niell et al, 2004). Dendritic compartments undergo dynamic regulation and demonstrate both morphological and synaptic plasticity (Engert and Bonhoeffer, 1999;Maletic-Savatic et al, 1999;Toni et al, 1999;Yuste and Bonhoeffer, 2001).…”

High-ResolutionIn VivoImaging of Hippocampal Dendrites and Spines

“…We observed the complete range of spine morphologies described previously in vitro and in fixed preparations (Parnass et al, 2000;Sorra and Harris, 2000;Yuste and Bonhoeffer, 2004). Spine densities measured in vivo and in fixed tissue were indistinguishable (fixed tissue, 0.87 Ϯ 0.24 spines/m, n ϭ 346 spines; in vivo, 0.92 Ϯ 0.15 spines/m, n ϭ 225 spines; t test; p ϭ 0.51).…”

Methamphetamine learning induces persistent nonmuscle myosin II-dependent spine motility in the basolateral amygdala

“…At P28-35, the pattern reversed, with BLA spines becoming more stable than those in CA1, making the impact of METH training on BLA motility at this age even more striking. In this series of experiments, we also confirmed that spine motility is actin-dependent in the BLA, as has been shown in cultured hippocampal cells and slices (35,37,39,45). This established that spine motility is an appropriate measure to determine the impact of METH on spine actin dynamics.…”

“…Because this was the first assessment of spine motility in the BLA, we first confirmed that motility rates decrease with age, as has been reported in cultured hippocampal cells and slices, dentate gyrus and CA1 acute slices, and primary visual cortex in vivo (34,35,(37)(38)(39)(40)45). This also allowed us to compare the rates of spine motility between the BLA and CA1 in early postnatal life and adolescence.…”

Calcium/Calmodulin-Dependent Protein Kinase II Alters Structural Plasticity and Cytoskeletal Dynamics inDrosophila

“…Molecular/genetic signaling determines this morphology and changing function by modulating microtubule-based dendritic shafts and actin-rich dendritic filopodia or spines (Fifkova and Delay, 1982;Matus et al, 1982;Micheva et al, 1998). Filopodia can serve multiple functions including acting as precursors to dendritic spines (Parnass et al, 2000) and pioneering the formation of dendritic arbors (Niell et al, 2004). Dendritic compartments undergo dynamic regulation and demonstrate both morphological and synaptic plasticity (Engert and Bonhoeffer, 1999;Maletic-Savatic et al, 1999;Toni et al, 1999;Yuste and Bonhoeffer, 2001).…”