@article{MTMT:1661000, title = {SYNCHRONIZATION OF NEURONAL-ACTIVITY IN HIPPOCAMPUS BY INDIVIDUAL GABAERGIC INTERNEURONS}, url = {https://m2.mtmt.hu/api/publication/1661000}, author = {COBB, SR and BUHL, EH and Halasy, Katalin and PAULSEN, O and Somogyi, Péter Pál}, doi = {10.1038/378075a0}, journal-iso = {NATURE}, journal = {NATURE}, volume = {378}, unique-id = {1661000}, issn = {0028-0836}, abstract = {SYNCHRONIZATION Of neuronal activity is fundamental in the operation of cortical networks(1). With respect to an ongoing synchronized oscillation, the precise timing of action potentials is an attractive candidate mechanism for information coding(2-5) Networks of inhibitory interneurons have been proposed to have a role in entraining cortical, synchronized 40-Hz activity(6,7). Here we demonstrate that individual GABAergic interneurons(8) can effectively phase spontaneous firing and subthreshold oscillations in hippocampal pyramidal cells at theta frequencies (4-7 Hz). The efficiency of this entrainment is due to interaction of GABA(A)-receptor-mediated hyperpolarizing synaptic events with intrinsic oscillatory mechanisms tuned to this frequency range in pyramidal cells. Moreover, this GABAergic mechanism is sufficient to synchronize the firing of pyramidal cells. Thus, owing to the divergence of each GABAergic interneuron(9,10), more than a thousand pyramidal cells may share a common temporal reference established by an individual interneuron.}, year = {1995}, eissn = {1476-4687}, pages = {75-78} } @article{MTMT:2138103, title = {Physiological properties of anatomically identified axo-axonic cells in the rat hippocampus.}, url = {https://m2.mtmt.hu/api/publication/2138103}, author = {Buhl, EH and Han, ZS and Lőrinczi, Zoltán and Stezhka, VV and Karnup, SV and Somogyi, Péter Pál}, journal-iso = {J NEUROPHYSIOL}, journal = {JOURNAL OF NEUROPHYSIOLOGY}, volume = {71}, unique-id = {2138103}, issn = {0022-3077}, abstract = {1. The properties of a well-defined type of GABAergic local circuit neuron, the axo-axonic cell (n = 17), were investigated in rat hippocampal slice preparations. During intracellular recording we injected axo-axonic cells with biocytin and subsequently identified them with correlated light and electron microscopy. Employing an immunogold-silver intensification technique we showed that one of the physiologically characterized cells was immunoreactive for gamma-aminobutyric acid (GABA). 2. Axo-axonic cells were encountered in the dentate gyrus (n = 5) as well as subfields CA3 (n = 2) and CA1 (n = 10). They generally had smooth, beaded dendrites that extended throughout all hippocampal layers. Their axons ramified densely in the cell body layers and in the subjacent stratum oriens or hilus, respectively. Tested with electron microscopy, labeled terminals (n = 53) established synapses exclusively with the axon initial segment of principal cells in strata oriens and pyramidale and rarely in lower radiatum. Within a 400-microns slice a single CA1 axo-axonic cell was estimated to be in synaptic contact with 686 pyramidal cells. 3. Axo-axonic cells (n = 14) had a mean resting membrane potential of -65.1 mV, an average input resistance of 73.9 M omega, and a mean time constant of 7.7 ms. Action potentials were of short duration (389-microseconds width at half-amplitude) and had a mean amplitude of 64.1 mV. 4. Nine of 10 tested cells showed a varying degree of spike frequency adaptation in response to depolarizing current injection. Current-evoked action potentials were usually curtailed by a deep (10.2 mV) short-latency afterhyperpolarization (AHP) with a mean duration of 28.1 ms. 5. Cells with strong spike frequency accommodation (n = 5) had a characteristic firing pattern with numerous spike doublets. These appeared to be triggered by an underlying depolarizing afterpotential. In the same cells, prolonged bursts of action potentials were followed by a prominent long-duration AHP with a mean time constant of 1.15 s. 6. Axo-axonic cells responded to the stimulation of afferent pathways with short-latency excitatory postsynaptic potentials (EPSPs) or at higher stimulation intensity with up to three action potentials. Axo-axonic cells in the dentate gyrus could be activated by stimulating the CA3 area as well as the perforant path, whereas in the CA1 area responses were elicited after shocks to the perforant path, Schaffer collaterals, and the stratum oriens-alveus border. 7. In the CA1 area the EPSP amplitude increased in response to membrane hyperpolarization.(ABSTRACT TRUNCATED AT 400 WORDS)}, keywords = {Animals; Female; RATS; Synaptic Transmission/*physiology; Nerve Net/*physiology; Electric Stimulation; Interneurons/*physiology/ultrastructure; Brain Mapping; Hippocampus/anatomy & histology/*physiology; gamma-Aminobutyric Acid/*physiology; Rats, Wistar; Neural Inhibition/physiology; Receptors, GABA/physiology; Receptors, N-Methyl-D-Aspartate/physiology; Membrane Potentials/physiology; Axons/*physiology/ultrastructure; Afferent Pathways/anatomy & histology/physiology; Dendrites/physiology/ultrastructure}, year = {1994}, eissn = {1522-1598}, pages = {1289-1307} } @article{MTMT:107599, title = {Precision and variability in postsynaptic target selection of inhibitory cells in the hippocampal CA3 region}, url = {https://m2.mtmt.hu/api/publication/107599}, author = {Gulyás, Attila and Miles, R and Hájos, Norbert and Freund, Tamás}, doi = {10.1111/j.1460-9568.1993.tb00240.x}, journal-iso = {EUR J NEUROSCI}, journal = {EUROPEAN JOURNAL OF NEUROSCIENCE}, volume = {5}, unique-id = {107599}, issn = {0953-816X}, year = {1993}, eissn = {1460-9568}, pages = {1729-1751}, orcid-numbers = {Gulyás, Attila/0000-0003-4961-636X} } @article{MTMT:107588, title = {Complete axon arborization of a single CA3 pyramidal cell in the rat hippocampus, and its relationship with postsynaptic parvalbumin-containing interneurons}, url = {https://m2.mtmt.hu/api/publication/107588}, author = {Sík, Attila and Tamamaki, N and Freund, Tamás}, doi = {10.1111/j.1460-9568.1993.tb00239.x}, journal-iso = {EUR J NEUROSCI}, journal = {EUROPEAN JOURNAL OF NEUROSCIENCE}, volume = {5}, unique-id = {107588}, issn = {0953-816X}, keywords = {Animals; Male; immunohistochemistry; RATS; Microscopy, Electron; Rats, Sprague-Dawley; Hippocampus/*physiology/ultrastructure; Pyramidal Cells/*physiology/ultrastructure; Axons/*physiology/ultrastructure; Parvalbumins/*metabolism; Presynaptic Terminals/physiology/ultrastructure; Biotin/analogs & derivatives/metabolism; Interneurons/metabolism/*physiology; Synapses/metabolism/*physiology/ultrastructure}, year = {1993}, eissn = {1460-9568}, pages = {1719-1728} } @article{MTMT:2379170, title = {Cellular organization of reciprocal patchy networks in layer III of cat visual cortex (area 17).}, url = {https://m2.mtmt.hu/api/publication/2379170}, author = {Kisvárday, Zoltán and Eysel, UT}, doi = {10.1016/0306-4522(92)90050-C}, journal-iso = {NEUROSCIENCE}, journal = {NEUROSCIENCE}, volume = {46}, unique-id = {2379170}, issn = {0306-4522}, abstract = {There is no direct information available concerning the exact spatial characteristics of long-range axons and their relationship with the patchy phenomena observed after extracellular injection of retrograde tracers. In the present study, using the recently introduced neuronal tracer biocytin, we demonstrate by detailed three-dimensional reconstruction of 10 pyramidal cells in layer III, that their clustered axonal terminals form a specific patchy network in layers II and III. The reconstructed network occupied an area of 6.5 x 3.5 mm parallel to the cortical surface elongated in an anteroposterior direction. The average centre-to-centre distance between patches within the network was 1.1 mm. On average, the axonal field of each of the 10 pyramidal cells contained a total of 417 boutons at four to eight distinct sites (patches), and in each patch, an average of 79 boutons was provided by the same cell. The identified connections between the patches were predominantly reciprocal. Detailed analyses have shown that many pyramidal cells of the network are directly interconnected so that each of them can receive one to four, chiefly axospinous, contacts onto the distal segment of its apical and basal dendrites from the axon of another pyramidal cell belonging to a different patch labelled from the same injection site. We hypothesize that the possible functional role of the network is to link remote sites with similar physiological characteristics, such as orientation preference, supporting the model of Mitchison and Crick [(1982) Proc. natn. Acad. Sci. U.S.A. 79, 3661-3665].}, keywords = {Animals; Interneurons/physiology; Lysine/analogs & derivatives; Histocytochemistry; Cats; Axons/physiology; Dendrites/physiology; Nerve Net/*cytology; Visual Cortex/*cytology; Pyramidal Tracts/physiology; Golgi Apparatus/physiology}, year = {1992}, eissn = {1873-7544}, pages = {275-286} } @article{MTMT:107535, title = {Synaptic targets of HRP-filled layer III pyramidal cells in the cat striate cortex}, url = {https://m2.mtmt.hu/api/publication/107535}, author = {Kisvárday, Zoltán and Martin, KAC and Freund, Tamás and Maglóczky, Zsófia and Whitteridge, D and Somogyi, Péter Pál}, doi = {10.1007/BF00340492}, journal-iso = {EXP BRAIN RES}, journal = {EXPERIMENTAL BRAIN RESEARCH}, volume = {64}, unique-id = {107535}, issn = {0014-4819}, keywords = {Animals; Microscopy, Electron; immunochemistry; Histocytochemistry; Cats; gamma-Aminobutyric Acid/metabolism; Synapses/ultrastructure; Visual Cortex/*cytology/metabolism/ultrastructure}, year = {1986}, eissn = {1432-1106}, pages = {541-552} } @article{MTMT:107687, title = {Glutamate decarboxylase-immunoreactive terminals of Golgi-impregnated axoaxonic cells and of presumed basket cells in synaptic contact with pyramidal neurons of the cat's visual cortex}, url = {https://m2.mtmt.hu/api/publication/107687}, author = {Freund, Tamás and Martin, KAC and Smith, AD and Somogyi, Péter Pál}, doi = {10.1002/cne.902210303}, journal-iso = {J COMP NEUROL}, journal = {JOURNAL OF COMPARATIVE NEUROLOGY}, volume = {221}, unique-id = {107687}, issn = {0021-9967}, year = {1983}, eissn = {1096-9861}, pages = {263-278} } @article{MTMT:2138124, title = {Physiological and morphological properties of identified basket cells in the cat's visual cortex.}, url = {https://m2.mtmt.hu/api/publication/2138124}, author = {Martin, KA and Somogyi, Péter Pál and Whitteridge, D}, doi = {10.1007/BF00239183}, journal-iso = {EXP BRAIN RES}, journal = {EXPERIMENTAL BRAIN RESEARCH}, volume = {50}, unique-id = {2138124}, issn = {0014-4819}, abstract = {In 87 cells studied physiologically, and filled intracellularly with horseradish peroxidase (HRP), we have found four cells which make multiple contacts with the perikarya of their post-synaptic targets. These cells are all multipolar non-pyramidal neurones with elongated smooth dendrites. Three resemble the classical "basket cells" of Ramon y Cajal (1911), having widely distributed axons which contribute to the "nids pericellulaires" around pyramidal cell perikarya. The fourth cell has a much more restricted axon virtually confined to layer 4 and appears to contact principally small, probably non-pyramidal, cells. Two of the basket cell axons have been examined by electron microscopy and make symmetrical, Gray's type II contacts with the perikarya and apical and basal dendrites of pyramidal cells. Ten percent of the synapses are on dendrites of non-pyramidal cells. The axon arborizations of all four cells are distributed in a patchy fashion. In two cells examined for the purpose, very few boutons were found within 100 micron of the cell body and a radially aligned cylinder of the same diameter extending from the cell body to the pial surface. The physiological properties of these structurally similar cells are far from uniform. They can be activated mono- or polysynaptically, by X- or Y-type lateral geniculate input, and can have S or C type receptive fields. Two were activated, probably monosynaptically, via callosal afferents. These cells may play an important role in the inhibitory mechanisms of the cortex.}, keywords = {Animals; Microscopy, Electron; Electrophysiology; Cats; Visual Cortex/*cytology/physiology; Visual Pathways/physiology; Geniculate Bodies/physiology}, year = {1983}, eissn = {1432-1106}, pages = {193-200} } @article{MTMT:107680, title = {The axo-axonic interneuron in the cerebral cortex of the rat, cat and monkey}, url = {https://m2.mtmt.hu/api/publication/107680}, author = {Somogyi, Péter Pál and Freund, Tamás and Cowey, A}, doi = {10.1016/0306-4522(82)90086-0}, journal-iso = {NEUROSCIENCE}, journal = {NEUROSCIENCE}, volume = {7}, unique-id = {107680}, issn = {0306-4522}, year = {1982}, eissn = {1873-7544}, pages = {2577-2607} } @article{MTMT:104933, title = {Vertical organization of neurons accumulating 3H GABA in the visual cortex of the rhesus monkey}, url = {https://m2.mtmt.hu/api/publication/104933}, author = {Somogyi, Péter Pál and Cowey, A and Halász, Norbert and Freund, Tamás}, doi = {10.1038/294761a0}, journal-iso = {NATURE}, journal = {NATURE}, volume = {294}, unique-id = {104933}, issn = {0028-0836}, year = {1981}, eissn = {1476-4687}, pages = {761-763} } @article{MTMT:2138566, title = {Projection of neostriatal spiny neurons to the substantia nigra. Application of a combined Golgi-staining and horseradish peroxidase transport procedure at both light and electron microscopic levels.}, url = {https://m2.mtmt.hu/api/publication/2138566}, author = {Somogyi, Péter Pál and Smith, AD}, doi = {10.1016/0006-8993(79)90084-2}, journal-iso = {BRAIN RES}, journal = {BRAIN RESEARCH}, volume = {178}, unique-id = {2138566}, issn = {0006-8993}, abstract = {One type of striatonigral neuron in the rat has been characterized. Golgi impregnation of striatal neurons that had been retrogradely labeled by horseradish peroxidase has shown that the medium-sized, densely spiny neurons project to the substantia nigra. Some of the synapses on three of these identified striatonigral neurons have been studied in the electron microscope following replacement of the Golgi deposit by means of the 'gold-toning' method. Synapsing axonal boutons were found on the following sites: soma and axon initial segment (symmetrical, with flattened or pleomorphic vesicles); primary and secondary dendritic shafts (symmetrical with pleomorphic vesicles); dendritic spines (asymmetrical, with spheroidal vesicles). These findings show that new information concerning neuronal connectivity can be obtained by combining three classical procedures in the same material: first, the Golgi method, that characterizes the type of neuron on the basis of its dendritic morphology; second, a retrograde tracing method, that identifies the projection area of the neuron; and, third, ultrastructural analysis of the nature of afferent terminals on the neuron.}, keywords = {Animals; Male; RATS; Synapses/physiology/ultrastructure; Staining and Labeling; Histocytochemistry; horseradish peroxidase; *Axonal Transport; Substantia Nigra/*cytology/physiology/ultrastructure; Neurons/*cytology/physiology/ultrastructure}, year = {1979}, eissn = {1872-6240}, pages = {3-15} } @article{MTMT:2138570, title = {The study of Golgi stained cells and of experimental degeneration under the electron microscope: a direct method for the identification in the visual cortex of three successive links in a neuron chain.}, url = {https://m2.mtmt.hu/api/publication/2138570}, author = {Somogyi, Péter Pál}, doi = {10.1016/0306-4522(78)90099-4}, journal-iso = {NEUROSCIENCE}, journal = {NEUROSCIENCE}, volume = {3}, unique-id = {2138570}, issn = {0306-4522}, keywords = {Animals; RATS; Microscopy, Electron; Dendrites/ultrastructure; Axons/ultrastructure; Staining and Labeling; Brain Mapping/*methods; Neurons/ultrastructure; Synapses/ultrastructure; Visual Cortex/*cytology; Visual Pathways/cytology; Geniculate Bodies/*cytology}, year = {1978}, eissn = {1873-7544}, pages = {167-180} } @article{MTMT:2138571, title = {A specific 'axo-axonal' interneuron in the visual cortex of the rat.}, url = {https://m2.mtmt.hu/api/publication/2138571}, author = {Somogyi, Péter Pál}, doi = {10.1016/0006-8993(77)90808-3}, journal-iso = {BRAIN RES}, journal = {BRAIN RESEARCH}, volume = {136}, unique-id = {2138571}, issn = {0006-8993}, keywords = {Animals; RATS; Synapses/*ultrastructure; Axons/*ultrastructure; Pyramidal Tracts/ultrastructure; Visual Cortex/*ultrastructure; Interneurons/*ultrastructure}, year = {1977}, eissn = {1872-6240}, pages = {345-350} }