Astrocytic complexity distinguishes the human brain

Oberheim, Nancy Ann; Wang, Xiaohai; Goldman, Steven A.

doi:10.1016/j.tins.2006.08.004

Cited by 625 publications

(568 citation statements)

References 60 publications

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“…Depending on the brain region, the tissue volume occupied by one (nonoverlapping) astrocyte in rodents varies between 20,000 and 80,000 µm 3 (Bushong et al, 2002; Halassa and Haydon, 2010; Oberheim et al, 2012), and 300 to 600 dendrites of principal neurons normally approach a single astrocyte (Halassa and Haydon, 2010). These relationships indicate that a single astrocyte approaches 20 to 120 thousand synapses in the rodent brain, and ∼270 thousand to 2 million synapses in the human brain (Bushong et al, 2002; Oberheim et al, 2009, 2006). …”

Section: Astroglial Coverage Of Synapsesmentioning

confidence: 99%

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Heller

Rusakov

2015

Glia

132

137

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Memory formation in the brain is thought to rely on the remodeling of synaptic connections which eventually results in neural network rewiring. This remodeling is likely to involve ultrathin astroglial protrusions which often occur in the immediate vicinity of excitatory synapses. The phenomenology, cellular mechanisms, and causal relationships of such astroglial restructuring remain, however, poorly understood. This is in large part because monitoring and probing of the underpinning molecular machinery on the scale of nanoscopic astroglial compartments remains a challenge. Here we briefly summarize the current knowledge regarding the cellular organisation of astroglia in the synaptic microenvironment and discuss molecular mechanisms potentially involved in use‐dependent astroglial morphogenesis. We also discuss recent observations concerning morphological astroglial plasticity, the respective monitoring methods, and some of the newly emerging techniques that might help with conceptual advances in the area. GLIA 2015;63:2133–2151

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Section: Astroglial Coverage Of Synapsesmentioning

confidence: 99%

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Heller

Rusakov

2015

Glia

132

137

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“…17 Second, the morphology had also changed; the human protoplasmic and fibrous astrocytes are 2 to 3 times larger as compared to rodents. 18,19 Even more importantly, the human astrocytes are immensely more complex 18 ; each human astrocytes has ϳ10 times more primary processes than the rodent one; the arborization is also infinitely more complex and human protoplasmic astrocyte covers and integrates ϳ2 million synapses, whereas rodent astrocytes cover ϳ20,000 to 120,000 synaptic contacts. In addition, several primate specific astrocytes (e.g.…”

Section: Glial Explosion Forms the Human Brainmentioning

confidence: 99%

Astrocytes in Alzheimer's Disease

et al. 2010

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Summary:The circuitry of the human brain is formed by neuronal networks embedded into astroglial syncytia. The astrocytes perform numerous functions, providing for the overall brain homeostasis, assisting in neurogenesis, determining the micro-architecture of the grey matter, and defending the brain through evolutionary conserved astrogliosis programs.Astroglial cells are engaged in neurological diseases by determining the progression and outcome of neuropathological process. Astrocytes are specifically involved in various neurodegenerative diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and various forms of dementia. Recent evidence suggest that early stages of neurodegenerative processes are associated with atrophy of astroglia, which causes disruptions in synaptic connectivity, disbalance in neurotransmitter homeostasis, and neuronal death through increased excitotoxicity. At the later stages, astrocytes become activated and contribute to the neuroinflammatory component of neurodegeneration.

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“…3 On the contrary, evolution of the nervous system resulted in great changes in the second type of neural cells, the neuroglia. 4 Indeed, phylogenetic advance in brain complexity and capabilities coincided with a remarkable increase in the number of glial cells: in the rodent cortex the glial to neurone ratio is about 0.3 : 1, whereas in humans the same ratio is several times higher being B1.65 :1, 5 while the total number of glial cells in the human brain is B10 (or even more) times larger than in lesser mammals. Astrocytes in higher primates display a much larger complexity as compared, for example with rodents.…”

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confidence: 99%

“…Astrocytes in higher primates display a much larger complexity as compared, for example with rodents. 4 The linear dimensions of human protoplasmic astroglial cells (which are the main type of glia in grey matter) are about 2.75 times larger and their volume is about 27 times greater than for the same cells in a mouse brain. Furthermore, human protoplasmic astrocytes have about 40 main processes and these processes have immensely more complex branching than mouse astrocytes (which bear only 3-4 main processes).…”

mentioning

confidence: 99%

“…As a result, every human protoplasmic astrocyte contacts and enwraps B2 million of synapses compared to only B100 000 synapses covered by the processes of a mouse astrocyte. 4 In addition to these quantitative changes, central nervous system (CNS) of Homo sapiens and other primates developed specific types of astroglia, the interlaminar astrocytes and polarised astrocytes, 4,6,7 which are absent from the brain of other species. The occurrence of interlaminar astrocytes is a very recent achievement of primate evolution.…”

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Glia: the fulcrum of brain diseases

et al. 2007

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Neuroglia represented by astrocytes, oligodendrocytes and microglial cells provide for numerous vital functions. Glial cells shape the micro-architecture of the brain matter; they are involved in information transfer by virtue of numerous plasmalemmal receptors and channels; they receive synaptic inputs; they are able to release 'glio'transmitters and produce long-range information exchange; finally they act as pluripotent neural precursors and some of them can even act as stem cells, which provide for adult neurogenesis. Recent advances in gliology emphasised the role of glia in the progression and handling of the insults to the nervous system. The brain pathology, is, to a very great extent, a pathology of glia, which, when falling to function properly, determines the degree of neuronal death, the outcome and the scale of neurological deficit. Glial cells are central in providing for brain homeostasis. As a result glia appears as a brain warden, and as such it is intrinsically endowed with two opposite features: it protects the nervous tissue as long as it can, but it also can rapidly assume the guise of a natural killer, trying to eliminate and seal the damaged area, to save the whole at the expense of the part. The sudden emergence of an intellect, and therefore a human being, which materialised only around a million years ago, remains the main mystery for our self-understanding. Similarly, we still do not know by which steps or transitions the human intellect emerged from the animal kingdom and where the fundamental difference between a man and an animal lies. According to the neuronal doctrine, which governs modern neuroscience since the beginning of the twentieth century, 1,2 the neurone is regarded as a basic information processing unit consisting of dendrites and axons with a unidirectional flow of information from the receiving dendrites via the integrating cell body to the terminal branches of the axon. Neuronal networks, connected through synaptic contacts, are generally considered as the substrate of our intellect.The number and size of neural cells increase with the size of the body and of the brain of mammals. This increasing quantity eventually has caused the generation of a new quality, the intellect. Rather amazingly, however, there is a relatively little difference in the morphology and physiology of neurones between humans and beasts; similarly the density of synaptic contacts in the brains of rodents and humans is more or less constant at around 1100-1300 millions/mm 3 . 3 On the contrary, evolution of the nervous system resulted in great changes in the second type of neural cells, the neuroglia. 4 Indeed, phylogenetic advance in brain complexity and capabilities coincided with a remarkable increase in the number of glial cells: in the rodent cortex the glial to neurone ratio is about 0.3 : 1, whereas in humans the same ratio is several times higher being B1.65:1, 5 while the total number of glial cells in the human brain is B10 (or even more) times larger than in lesser mammals. Astrocytes ...

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Astrocytic complexity distinguishes the human brain

Cited by 625 publications

References 60 publications

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Morphological plasticity of astroglia: Understanding synaptic microenvironment

Astrocytes in Alzheimer's Disease

Glia: the fulcrum of brain diseases

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