Abstract
An electron microscopy study was made of synaptic organization in the cat association cortex, area 5b. A total of 1635 axonal terminals were discovered over 6215 µm2 (240 electronic imagings of slices of different association cortex layers); i.e., an average of 263±16 terminals per 1000 µm2 expanse. It was found that 75.5% of axon terminals contained synaptic vesicles and formed either one- or two-sided contact with postsynaptic structures; 24.5% of axonal terminals contained synaptic vesicles but formed no distinct synaptic contacts with nearby neurons; 84.9% of terminals contained round-shaped or slightly oval synaptic vesicles; 7.8% had both rounded and elongated shapes, and vesicles were very elongated in the remaining 7.3%. Of the axonal terminals having synaptic contacts, axo(dendritic)-spinal terminals accounted for 46.6%, and axodendritic and axosomatic endings amounted to 50.0% and 3.4% respectively (in all 77% of axosomatic terminals contained elongated vesicles and maintained symmetrical contact, while 23% had round-shaped vesicles and formed asymmetrical contact). Calculations show that for each 1 mm3 an average of 258 million axonal terminals are found forming synaptic contacts in the cat association cortex as well as 84 million terminals containing synaptic vesicles but not forming contact.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Literature cited
O. S. Adrianov, V. P. Babmindra, L. A. Kukuev, and T. A. Tolchenova, "Structural pattern of thalamoparietal relationships," in: Evolution of Function of the Parietal Lobe [in Russian], Nauka, Leningrad (1973), pp. 7–14.
D. P. Artemenko and T. M. Mamonets, "Neuronal response in the posterior suprasylvian gyrus to different stimuli," Neirofiziologiya,4, No. 4, 375–383 (1972).
V. N. Kazkov and V. A. Izmest'ev, "Microelectrode study of neuronal organization in the parietal association cortex," Neirofiziologiya,4, No. 4, 54–60 (1972).
V. N. Kazakov and V. A. Izmest'ev, "Neuronal response in the association area to stimulation of primary sensory zones," Neirofiziologiya,4, No. 4, 524–530 (1972).
V. A. Maiskii and F. N. Serkov, "Thalamic sources of afferent projections to the feline association cortex retrogradely labeled with horseradish peroxidase and fluorochrome," Fiziol. Zh.,32, No. 6, 722–732 (1986).
T. M. Mamonets, "Convergence of transcallosal and other afferent impulses in neurons of the cat association cortex," Fiziol. Zh.,29, No. 6, 666–672 (1983).
S. P. Narikashvili, "Association cortex and its relationships with sensory zones," Zh. Vyssh. Nerv. Deyat.,19, No.1, 110–123 (1969).
F. N. Serkov, Cortical Inhibition, Nauk, Dumka, Kiev (1986).
F. N. Serkov and E. D. Genis, "Qualitative and quantitative description of synapses in different auditory cortex layers," Neirofiziologiya,12, No. 2, 131–137 (1980).
F. N. Serkov and Yu. A. Gonchar, "Density of synapses in association cortex (area 5b) in the cat," Fiziol. Zh.,34, No. 5, 21–26 (1988).
F. N. Serkov, I. I. Shelest, and N. A. Soroka, "Actual cortical and association convergence of multimodal impulses in feline parietal association cortex," Fiziol. Zh.,33, No. 5, 63–68 (1987).
F. N. Serkov and E. Sh. Yanovskii, "Local inhibition in cortical dendrites," Dokl. Akad. Nauk, SSSR,282, No. 3, 750–752 (1985).
C. Beaulieu and M. Colonnier, "A laminar analysis of the number of round-asymmetrical and flat-symmetrical synapses on spines, dendritic trunks and cell bodies in area 17 of the cat," J. Comp. Neurol.,231, No. 2, 180–189 (1985).
E. Bental and B. Bihari, "Evoked activity of single neurons in sensory association cortex of the cat," J. Neurophysiol.,26, No. 2, 207–214 (1963).
M. Colonnier, "Synaptic pattern on different cell types in the different laminae of the cat visual cortex," Brain Res.,9, No. 2, 268–287 (1968).
R. Dubner and L. T. Rutledge, "Recording and analysis of converging input upon neurons in cat association cortex," J. Neurophysiol.,27, No. 4, 620–634 (1964).
R. Dubner and L. Rutledge, "Intracellular recording of the convergence of input upon neurons in cat association cortex," Exp. Neurol.,12, No. 4, 349–369 (1965).
A. Fairen and F. Valverde, "A specialized type of neuron in the visual cortex of cat: a Golgi and electron microscope study of chandelier cells," J. Comp. Neurol.,194, No. 6, 761–780 (1980).
A. M. Graybiel, "Some thalamocortical projections of the pulvinar-posterior systems of the thalamus in the cat," Brain Res.,22, No. 1, 131–136 (1970).
Y. E. Gruner, J. C. Hirsch, and C. Sotelo, "Ultrastructural features of the isolated suprasylvian gyrus in the cat," J. Comp. Neurol.,154, No. 1, 1–28 (1974).
A. Hendrickson, S. P. Hunt, and J.-Y. Wu, "Immunocytochemical localization of glutamic acid decarboxylase in monkey striate cortex," Nature,292, No. 5, 1029–1031 (1983).
S. H. Hendry, C. R. Houser, E. G. Jones, and J. E. Vaughn, "Synaptic organization of immunocytochemically identified GABA neurons in the monkey sensorimotor cortex," J. Neurocytol.,12, No. 1, 639–660 (1983).
C. R. Houser, J. E. Vaughn, S. H. Hendry, et al., "GABA neurons in the cerebral cortex," in: Cerebral Cortex, Vol. 2, A. Peters and E. G. Jones, editors, Plenum Press, New York (1984), pp. 63–91.
E. G. Jones and S. H. C. Hendry, "Basket cells," in: Cerebral Cortex, Vol. 1, A. Peters and E. G. Jones, editors, Plenum Press, New York (1984), pp. 309–336.
T. Kaiseman-Abramov and A. Peters, "Some aspects of the morphology of Betz cells in the cerebral cortex of the cat," Brain Res.,43, No. 2, 527–546 (1972).
H. Kennedy, "Types of synapses contacting the soma of corticotectal cells in the visual cortex of the cat," Neuroscience,7, No. 9, 2159–2164 (1982).
K. Niimi, H. Matsuoka, Y. Yamazaki, and T. Katayama, "Thalamic afferents to the anterior and middle suprasylvian gyri in the cat traced with horseradish peroxidase," J. Hirnforsch.,24, No. 2, 173–187 (1983).
A. Peters, C. C. Proskauer, and C. E. Ribau, "Chandelier cells in rat visual cortex," J. Comp. Neurol.,206, No. 3, 397–416 (1982).
D. A. Sholl, The Organisation of the Cerebral Cortex, Methuen, London (1956).
P. Somogyi, T. F. Freund, and A. Cowey, "The axoaxonic interneuron in the cerebral cortex of the rat, cat and monkey," Neuroscience,7, No. 11, 2577–2608 (1982).
Additional information
A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 174–185, March–April, 1989.
Rights and permissions
About this article
Cite this article
Serkov, F.N., Gonchar, Y.A. & Pelevin, Y.M. Synaptic organization of the cat parietal association cortex (area 5b). Neurophysiology 21, 127–136 (1989). https://doi.org/10.1007/BF01056970
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01056970