Dimensions and density of dendritic spines from rat dentate granule cells based on reconstructions from serial electron micrographs

Trommald, Mari; Hulleberg, G

doi:10.1002/(sici)1096-9861(19970106)377:1<15::aid-cne3>3.0.co;2-m

Cited by 79 publications

(62 citation statements)

References 65 publications

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“…In addition, DIP spines have significantly longer PSDs and a higher percentage of perforated synapses than DIN spines. PSD length is known to correlate with spine size (Trommald and Hulleberg, 1997;Toni et al, 2001;Meng et al, 2002;Fujisawa et al, 2006), and perforated synapses are larger than those of nonperforated (simple) synapses (Calverley and Jones, 1990;Jones and Harris, 1995;Muller, 1997;Toni et al, 2001). Our results are the first to show that larger spine head areas, longer PSDs, and perforated PSDs are associated with another characteristic, abundance of drebrin A.…”

Section: Discussionsupporting

confidence: 57%

Drebrin a content correlates with spine head size in the adult mouse cerebral cortex

Kobayashi

Aoki²,

Kojima

et al. 2007

J of Comparative Neurology

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Synaptic activities alter synaptic strengths at the axospinous junctions, and such changes are often accompanied by changes in the size of the postsynaptic spines. We have been exploring the idea that drebrin A, a neuron-specific actin-binding protein localized on the postsynaptic side of excitatory synapses, may be a molecule that links synaptic activity to the shape and content of spines. Here, we performed electron microscopic immunocytochemistry with the nondiffusible gold label to explore the relationship among levels of drebrin A, the NR2A subunit of N-methyl-D-aspartate receptors, and the size of spines in the perirhinal cortex of adult mouse brains. In contrast to the membranous localization within neonatal spines, most immunogold particles for drebrin A were localized to the cytoplasmic core region of spines in mature spines. This distribution suggests that drebrin within adult spines may reorganize the F-actin network at the spine core, in addition to its known neonatal role in spine formation. Drebrin A-immunopositive (DIP) spines exhibited larger spine head areas and longer postsynaptic densities (PSDs) than drebrin A-immunonegative (DIN) spines (P < 0.001). Furthermore, spine head area and PSD lengths correlated positively with drebrin A levels (r = 0.47 and 0.40). The number of synaptic NR2A immunolabels was also higher in DIP spines than in DIN spines, whereas their densities per unit lengths of PSD were not significantly different. These differences between the DIP and the DIN spines indicate that spine sizes and synaptic protein composition of mature brains are regulated, at least in part, by drebrin A levels.

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Section: Discussionsupporting

confidence: 57%

Drebrin a content correlates with spine head size in the adult mouse cerebral cortex

Kobayashi

Aoki²,

Kojima

et al. 2007

J of Comparative Neurology

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“…Notably, our study indicates that stubby spines are greatly over-reported in the light-microscopic literature, due to insufficient optical resolution. This conclusion is supported by electron microscopy studies that typically observe only low fractions (a few percent) of stubby spines in adult tissue 24,25,38,43 . This is not merely a semantic issue because spines with large heads and thin and short necks (e.g.…”

mentioning

confidence: 67%

“…Electron microscopy studies have provided exquisitely detailed and quantitative analyses of spine morphology in fixed samples 24,38,39 , but a comparable analysis in live tissue has been lacking. Our STED images reveal a high degree of heterogeneity of spine sizes and morphologies, which agrees well with the previous electron microscopy work, but argues against morphological categorization schemes commonly used in the light microscopic literature [40][41][42] .…”

Section: Resolving Live Spine Morphologymentioning

confidence: 99%

Spine neck plasticity regulates compartmentalization of synapses

et al. 2014

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Dendritic spines have been proposed to transform synaptic signals through chemical and electrical compartmentalization. However, the quantitative contribution of spine morphology to synapse compartmentalization and its dynamic regulation are still poorly understood.We used time-lapse superresolution STED imaging in combination with FRAP measurements, 2-photon glutamate uncaging, electrophysiology and simulations to investigate the dynamic link between nanoscale anatomy and compartmentalization in live spines of CA1 neurons in mouse brain slices.We report a diversity of spine morphologies that argues against common categorization schemes, and establish a close link between compartmentalization and spine morphology, where spine neck width is the most critical morphological parameter. We demonstrate that spine necks are plastic structures that become wider and shorter after LTP. These morphological changes are predicted to lead to a substantial drop in spine head EPSP, while leaving overall biochemical compartmentalization preserved. 3 Dendritic spines form the postsynaptic component of most excitatory synapses, whose plasticity is essential for brain development and higher brain functions 1,2 . In addition to the molecular composition of the synapse, the morphology of spines is thought to be critical for synaptic function, as spine head size correlates with synaptic strength 3,4 and undergoes changes during synaptic plasticity [5][6][7][8] . Even so, our understanding of how spine structure shapes synapse function remains fragmented.It is well established that spines compartmentalize biochemical signals 9 . By contrast, the quantitative contribution of spine morphology to compartmentalization is still unknown, and only moderate correlations between spine neck length or head volume and chemical diffusion have been reported [9][10][11] . It is an open question to what extent biochemical compartmentalization is determined primarily by spine geometry or intracellular factors such as organelles or protein assemblies.Concerning electrical compartmentalization, it is not clear how electrical signals are transformed by the spine neck 9,[12][13][14] . This is an important question because synaptic strength may be adjusted through structural changes in spine necks, which has been a long-standing hypothesis 15,16 . An early electron microscopy study reported that the average spine head becomes larger and the neck wider and shorter after the induction of long-term plasticity (LTP) 17 , which was corroborated more recently by work based on 2-photon microscopy 6,18,19 . However, it is not known how these structural changes might affect biochemical and electrical compartmentalization, because 2-photon microscopy does not have sufficient spatial resolution to properly resolve spines and electron microscopy cannot be combined with functional assays. 4 Here, we combined stimulated emission depletion (STED) microscopy, fluorescence recovery after photo-bleaching (FRAP) experiments, 2-photon glutamate uncaging, and patch-clam...

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“…In a similar analysis of the control material we failed to detect spine classes based on distribution histograms or scatterplots (Trommald and Hulleberg 1996). After LTP induction, neither distribution plots of head volume, minimal cross-sectional area, PSD area, nor spine length revealed any multimodality in the distribution plots (data not shown).…”

Section: Spine Dimensionsmentioning

confidence: 79%

Long-term potentiation is associated with new excitatory spine synapses on rat dentate granule cells.

Trommald¹,

Hulleberg²,

Andersen³

1996

Learning & Memory

106

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IntroductionTo investigate possible morphological correlates to long-term potentiation (LTP), three-dimensional reconstruction of serial electron micrographs was employed. LTP was induced in the perforant path/dentate granule cell synapse in two rats. The surgically isolated contralateral side served as control, along with two untreated animals. Longitudinally sectioned and transversally sectioned dendrites were sampled from the middle fifth of the molecular layer and all visibly connected spines were identified. A mixed, unbalanced, nested variance component model was used to make a valid statistical comparison between the LTP and control groups.The spine density was higher in the experimental than in the control groups. The changes were statistically significant in both the longitudinal and transverse sample. In addition, spines with a divided stem and two heads (bifurcating spines) were seen at a higher frequency in the LTP material compared with the contralateral material. From a subset of dendrites all connected spines were reconstructed and detailed measurements of head, neck, and PSD dimensions were made. We failed to find significant differences following LTP on either of the dimensions measured. The results suggest that new spine synapses are formed following LTP, including some of the bifurcating type.1Corresponding author.The hippocampal formation is important for spatial navigation in rodents. Surgical or excitotoxic lesions of the hippocampal formation results in reduced learning behavior in a spatial learning task like the water maze (Morris et al. 1986; Morris et al. 1990). Rodents that are dependent on good spatial navigation like long-ranging male prairie voles have larger hippocampi than closely related species with smaller territories or nonroaming female voles (Jacobs et al. 1990). Furthermore, food-storing species of birds also have a larger volume of the dorso-medial cortex, a likely avian counterpart of the hippocampus (Krebs et al. 1989). Hippocampal damage in man causes large learning and memory deficits, including those coupled to spatial behavior (Squire 1992).In a search for basic mechanisms that might subserve the hippocampal participation in learning behavior, a process that strengthens certain synapses would be an interesting candidate, in particular if it had sufficient duration to fit the long duration of spatial learning. Long-term potentiation (LTP) is a cellular model that has several properties suitable for a role in learning behavior (Bliss and Collingridge 1993). First, LTP can be induced by repetitive activity of afferent impulses within the physiological range of hippocampal neurons. Second, the effect is very long-lasting, up to several weeks or even months in an awake, behaving animal (Bliss and Gardner-Medwin 1973;Barnes 1979). Most important, long-term potentiation allows associativity between synapses belonging to two afferent systems. Simultaneous activation of NMDA (N-methyl-n-aspartate)-receptor operated synaptic channels and AMPA (0t-aminohydroxy-isoxaz...

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Dimensions and density of dendritic spines from rat dentate granule cells based on reconstructions from serial electron micrographs

Cited by 79 publications

References 65 publications

Drebrin a content correlates with spine head size in the adult mouse cerebral cortex

Drebrin a content correlates with spine head size in the adult mouse cerebral cortex

Spine neck plasticity regulates compartmentalization of synapses

Long-term potentiation is associated with new excitatory spine synapses on rat dentate granule cells.

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