Three-dimensional synaptic organization of the human hippocampal CA1 field

Montero-Crespo, Marta; Domínguez-Álvaro, Marta; Rondon-Carrillo, Patricia; Alonso‐Nanclares, Lidia; DeFelipe, Javier; Blázquez-Llorca, Lidia

doi:10.1101/2020.02.25.964080

Cited by 9 publications

(21 citation statements)

References 56 publications

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“…Most synapses presented a simple, macular shape (around 87% for both AS and SS), in agreement with previous reports in different brain areas and species 44,45,46,38,30 . In our study, non-macular synapses constituted around 13% of the total synapses.…”

Section: Synaptic Shape Synaptic Size and Curvaturesupporting

confidence: 92%

“…In the present study, we found that the AS:SS ratio was 96.25:3.75. Preliminary results from our laboratory, using the FIB/SEM methodology, have shown that the AS:SS ratios are 98:2 and 96:4 in the stratum radiatum of the mouse and human CA1, respectively 29,30 . That is, the ratio of AS and SS in the CA1 field is similar in humans and rodents.…”

Section: Ratio Of As and Ssmentioning

confidence: 99%

“…We found a synaptic density of 2.52 synapses / µm 3 . Using FIB/SEM, we have previously shown that the synaptic density in the stratum radiatum of CA1 of the mouse is 2.36 synapses / µm 3 (29) , whereas in the stratum radiatum of CA1 of the human hippocampus, it is 0.67 synapses / µm 3 (30) . Thus, the synaptic density of the rat and mouse is remarkably similar but there are huge differences in synaptic density between humans and rodents.…”

Section: Synaptic Densitymentioning

confidence: 99%

“…We found that the spatial organization of synapses was nearly random, with slight deviations which could be explained by the presence of large apical dendrites in stratum radiatum that leave relatively large spaces free of synapses (see Figure 3d). Randomly distributed synapses have been described in the somatosensory cortex of normal rats and the frontal and transentorhinal cortices and hippocampus of the human brain 40,41,37,30 , suggesting that this synaptic characteristic is a widespread 'rule' of the cerebral cortex of different species.…”

Section: Spatial Distributionmentioning

confidence: 99%

“…Regarding axospinous AS, they are especially abundant (94.21%) when compared to other brain regions in both humans and other species 34,42,43,39,36,35,24,38,30 . For example, in the stratum radiatum of the human CA1 and the somatosensory cortex of the rat, axospinous AS represent around 75% of the total synaptic population 24,30 and in layer II of the human transentorhinal cortex or the stratum lacunosum-moleculare of the human CA1, axospinous AS are even less numerous and account for around 55% of the total synaptic population 38,30 .…”

Section: Postsynaptic Targetsmentioning

confidence: 99%

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3d Synaptic Organization of the Rat Ca1 and Alterations Induced by Cocaine Self-Administration

Blázquez-Llorca

Miguéns

Montero-Crespo

et al. 2020

Preprint

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The hippocampus plays a key role in contextual conditioning and has been proposed as an important component of the cocaine addiction brain circuit.To gain knowledge about cocaine-induced alterations in this circuit, we used Focused Ion Beam milling/Scanning Electron Microscopy (FIB/SEM) to reveal and quantify the 3D synaptic organization of the stratum radiatum of rat CA1, under normal circumstances and after cocaine-self administration (SA). Most synapses are asymmetric (excitatory), macular-shaped, and in contact with spine heads. After cocaine-SA, the size and complexity of both asymmetric and symmetric (inhibitory) synapses increased but no changes were observed in the synaptic density.This work constitutes the first detailed report on the 3D synaptic organization in the stratum radiatum of the CA1 field of cocaine-SA rats. Our data contribute to the elucidation of the normal and altered synaptic organization of the hippocampus, which is crucial for better understanding the neurobiological mechanisms underlying cocaine addiction.

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Section: Synaptic Shape Synaptic Size and Curvaturesupporting

confidence: 92%

Section: Ratio Of As and Ssmentioning

confidence: 99%

Section: Synaptic Densitymentioning

confidence: 99%

Section: Spatial Distributionmentioning

confidence: 99%

Section: Postsynaptic Targetsmentioning

confidence: 99%

See 3 more Smart Citations

3d Synaptic Organization of the Rat Ca1 and Alterations Induced by Cocaine Self-Administration

Blázquez-Llorca

Miguéns

Montero-Crespo

et al. 2020

Preprint

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Cortical synapses of the world's smallest mammal: An FIB/SEM study in the Etruscan shrew

Alonso‐Nanclares

Toledo-Rodriguez

Merchán-Pérez

et al. 2022

J of Comparative Neurology

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The main aim of the present study was to determine if synapses from the exceptionally small brain of the Etruscan shrew show any peculiarities compared to the much larger human brain. We analyzed the cortical synaptic density and a variety of structural characteristics of 7,239 3D reconstructed synapses, using using Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM). We found that some of the general synaptic characteristics are remarkably similar to those found in the human cerebral cortex. However, the cortical volume of the human brain is about 50,000 times larger than the cortical volume of the Etruscan shrew, while the total number of cortical synapses in human is only 20,000 times the number of synapses in the shrew, and synaptic junctions are 35% smaller in the Etruscan shrew. Thus, the differences in the number and size of synapses cannot be attributed to a brain size scaling effect but rather to adaptations of synaptic circuits to particular functions.

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Novel characterization of the relationship between verbal list‐learning outcomes and hippocampal subfields in healthy adults

Cremona

Mellet

Petit

et al. 2021

Human Brain Mapping

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The relationship between hippocampal subfield volumetry and verbal list‐learning test outcomes have mostly been studied in clinical and elderly populations, and remain controversial. For the first time, we characterized a relationship between verbal list‐learning test outcomes and hippocampal subfield volumetry on two large separate datasets of 447 and 1,442 healthy young and middle‐aged adults, and explored the processes that could explain this relationship. We observed a replicable positive linear correlation between verbal list‐learning test free recall scores and CA1 volume, specific to verbal list learning as demonstrated by the hippocampal subfield volumetry independence from verbal intelligence. Learning meaningless items was also positively correlated with CA1 volume, pointing to the role of the test design rather than word meaning. Accordingly, we found that association‐based mnemonics mediated the relationship between verbal list‐learning test outcomes and CA1 volume. This mediation suggests that integrating items into associative representations during verbal list‐learning tests explains CA1 volume variations: this new explanation is consistent with the associative functions of the human CA1.

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Three-dimensional synaptic organization of the human hippocampal CA1 field

Cited by 9 publications

References 56 publications

3d Synaptic Organization of the Rat Ca1 and Alterations Induced by Cocaine Self-Administration

3d Synaptic Organization of the Rat Ca1 and Alterations Induced by Cocaine Self-Administration

Cortical synapses of the world's smallest mammal: An FIB/SEM study in the Etruscan shrew

Novel characterization of the relationship between verbal list‐learning outcomes and hippocampal subfields in healthy adults

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