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Synaptic organization of cortico‐cortical communication in primates
Author(s) -
Ashaber Maria,
Zalányi László,
Pálfi Emese,
Stuber István,
Kovács Tamás,
Roe Anna W.,
Friedman Rob M.,
Négyessy László
Publication year - 2020
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.14905
Subject(s) - neuroscience , anterograde tracing , macaque , postsynaptic potential , somatosensory system , axon , postsynaptic density , cerebral cortex , biology , cortex (anatomy) , excitatory postsynaptic potential , central nervous system , inhibitory postsynaptic potential , biochemistry , receptor
In cortical circuitry, synaptic communication across areas is based on two types of axon terminals, small and large, with modulatory and driving roles, respectively. In contrast, it is not known whether similar synaptic specializations exist for intra‐areal projections. Using anterograde tracing and three‐dimensional reconstruction by electron microscopy (3D‐EM), we asked whether large boutons form synapses in the circuit of somatosensory cortical areas 3b and 1. In contrast to observations in macaque visual cortex, light microscopy showed both small and large boutons not only in inter‐areal pathways, but also in long‐distance intrinsic connections. 3D‐EM showed that correlation of surface and volume provides a powerful tool for classifying cortical endings. Principal component analysis supported this observation and highlighted the significance of the size of mitochondria as a distinguishing feature of bouton type. The larger mitochondrion and higher degree of perforated postsynaptic density associated with large rather than to small boutons support the driver‐like function of large boutons. In contrast to bouton size and complexity, the size of the postsynaptic density appeared invariant across the bouton types. Comparative studies in human supported that size is a major distinguishing factor of bouton type in the cerebral cortex. In conclusion, the driver‐like function of the large endings could facilitate fast dissemination of tactile information within the intrinsic and inter‐areal circuitry of areas 3b and 1.