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Cited by 253Neuroscience and Neuropharmacology ResearchNeurogenesis and neuroplasticity mechanismsMotor Control and Adaptation

Changes in synaptic density in motor cortex of rhesus monkey during fetal and postnatal life

Zecevic, Nada, Bourgeois, Jean-Pierre, Rakic, Pasko·1989·Developmental Brain Research
DOI 10.1016/0165-3806(89)90124-7
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Abstract

The density and proportion of synaptic contacts in the primate motor cortex (Brodmann area 4) were determined in 21 rhesus monkeys ranging in age from embryonic day 41 (E41) to 20 years. Two to 4 vertical electron microscopic probes, each consisting of 150-250 overlapping micrographs traversing the thickness of the cortex, were prepared for each specimen. Synapses were categorized according to their morphology (symmetrical or asymmetrical), cellular location (on spines, shafts or soma), number, and ratio of laminar distribution. The density of synapses was expressed per unit area and volume of neuropil (excluding neuronal and glia cell bodies, myelin sheath, blood vessels and extracellular space). The first synapse in the area of the emerging motor cortex were observed at E53 in the marginal zone (prospective layer I) and in the transient subplate zone situated beneath the developing cortical plate. Around midgestation (E89) synapses were observed over the entire width of the cortical plate, and their density was about 5/100 microns 3 of neuropil. During the last two months of gestation synaptic density increased 8-fold across all layers to reach about 40/100 microns 3 at the time of birth (E165). Synaptic production continued postnatally and by the end of the second postnatal month attained a level of 60/100 microns 3 neuropil which is two times higher than in the adults. This level decreased at a slow rate until sexual maturity (3 years of age) and then more rapidly to the adult level which is characterized by relative stability of about 30/100 microns 3. The decline in synaptic density after the peak in infancy occurs predominantly at the expense of asymmetric synapses situated on dendritic spines; the population of symmetric synapses on dendritic shafts remains relatively constant. The development of synaptic connections in the motor cortex of non-human primates involves initial overproduction followed by selective elimination and structural alterations.

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  • Region-specific differences in GM maturation may result from the underlying heterochronous synaptic pruning in the cortex, as has been shown in primate and human cerebral cortical development.

    “Thus, region-specific differences in GM maturation may result from the underlying heterochronous synaptic pruning in the cortex, as has been shown in the primate and human cerebral cortical development (18, 45–48).”

    From Dynamic mapping of human cortical development during childhood through early adulthood (2004) · cites this paper as [47]

  • Synaptic pruning of excitatory contacts is the signature morphologic event of late brain maturation during adolescence.

    “Synaptic pruning of excitatory contacts is the signature morphologic event of late brain maturation during adolescence.”

    From A role for synaptic plasticity in the adolescent development of executive function (2013) · cites this paper as [36]

  • In the non-human primate, synaptic density in multiple cortical areas synchronously increases, peaks during the postnatal 3rd month, declines slowly (10%) until ∼2 years of age, with a steeper decline (40%) occurring between 2.7 and 5 years (adulthood).

    “Quantitative analyses of synapses in the non-human primate uncovered a synchronous increase in synaptic density in multiple cortical areas that peaks during the postnatal 3rd month, declines slowly (10%) until∼2 years of age with a steeper decline (40%) occurring between 2.7 and 5 years (adulthood).35, 36, 37, 38”

    From A role for synaptic plasticity in the adolescent development of executive function (2013) · cites this paper as [36]

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Authors
Zecevic, N., Bourgeois, J.-P., & Rakic, P.
Affiliations
Yale University (US)
Corresponding author
Rakic, Pasko
ORCID
Rakic, Pasko
Venue
Developmental Brain Research
Publisher
Elsevier BV
Published
1989-11
Volume
50
Issue
1
Pages
11-32
ISSN
0165-3806 (ISSN-L)
DOI
10.1016/0165-3806(89)90124-7
OpenAlex
W2053373257
Cited by
253
References
100
Citations by year
2026: 1 · 2025: 5 · 2024: 7 · 2023: 5 · 2022: 3 · 2021: 5 · 2020: 5 · 2019: 8 · 2018: 1 · 2017: 7 · 2016: 4 · 2015: 7 · 2014: 7 · 2013: 10 · 2012: 8
FWCI
3.71
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Developmental Brain Research (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Yale University
  • Centers for Disease Control and Prevention (PR00168)
  • National Institute of Neurological Disorders and Stroke (NS-22807, NS 14841)
Topics
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Neuroscience › Developmental Neuroscience › Neurogenesis and neuroplasticity mechanisms
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Motor Control and Adaptation
Keywords
synaptic density, motor cortex, Brodmann area 4, rhesus monkeys, cortical development, fetal development, postnatal development, synaptic pruning, dendritic spines, asymmetric synapses, cortical lamination, subplate, neuropil
MeSH terms
Aging, Animals, Cell Count, Embryonic and Fetal Development, Macaca, Macaca mulatta, Motor Cortex, Synapses

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