@article{2616,
  abstract     = {Neurons in the rat cerebral cortex are enriched in group I metabotropic glutamate receptor (mGluR) subtypes and respond to their activation during development. To understand better the mechanisms by which mGluR1 and mGluR5 mediate these effects, the goal of this study was to elucidate the expression pattern and to determine the cellular and the precise subcellular localization of these two receptor subtypes in the rat neocortex and hippocampus during late prenatal and postnatal development. At the light microscopic level, mGluR1 α and mGluR5 were first detected in the cerebral cortex with different expression levels at embryonic day E18. Thus, mGluR5 had a moderate expression, whereas mGluR1 α was detected as a diffuse and weak labeling. mGluR5 was localized in some Cajal-Retzius cells as well as in other cell types, such as pioneer neurons of the marginal zone. During postnatal development, the distribution of the receptors dramatically changed. From P0 to around P10, mGluR1α was localized in identified, transient Cajal-Retzius cells of neocortex and hippocampus, until these cells disappear. In addition, a population of interneurons localized the receptor from the second/third postnatal week. In contrast, mGluR5 was localized mainly in pyramidal cells and in some interneurons, with a neuropilar staining throughout the cerebral cortex. At the electron microscopic level, the immunoreactivity for both group I mGluR subtypes was expressed postsynaptically. Using immunogold methods, mGluR1α and mGluR5 immunoreactivities were found throughout postnatal development at the edge of postsynaptic specialization of asymmetrical synapses. These results show that the two group I mGluRs have a differential expression pattern in neocortex and hippocampus that may suggest roles for the receptors in the early processing of cortical information and in the control of cortical developmental events.},
  author       = {López Bendito, Guillermina and Shigemoto, Ryuichi and Fairén, Alfonso and Luján, Rafael},
  issn         = {1047-3211},
  journal      = {Cerebral Cortex},
  number       = {6},
  pages        = {625 -- 638},
  publisher    = {Oxford University Press},
  title        = {{Differential distribution of group I metabotropic glutamate receptors during rat cortical development}},
  doi          = {10.1093/cercor/12.6.625},
  volume       = {12},
  year         = {2002},
}

@article{2619,
  abstract     = {The release of glutamate and GABA is modulated by presynaptic metabotropic glutamate receptors (mGluRs). We used immunocytochemical methods to define the location of the group III receptor mGluR7a in glutamatergic and GABAergic terminals innervating GABAergic interneurons and pyramidal cells. Immunoreactivity for mGluR7a was localized in the presynaptic active zone of both identified GABAergic and presumed glutamatergic terminals. Terminals innervating dendritic spines showed a variable level of receptor immunoreactivity, ranging from immunonegative to strongly immunopositive. The frequency of strongly mGluR7a positive terminals innervating the soma and dendrites of mGluR1α/somatostatin-expressing interneurons was very high relative to other neurons. On dendrites that received mGluR7a-enriched glutamatergic innervation, at least 80% of GABAergic terminals were immunopositive for mGluR7a. On such dendrites virtually all (95%) vasoactive intestinal polypeptide (VIP) positive (GABAergic) terminals were enriched in mGluR7a. The targets of VIP/mGluR7a-expressing terminals were mainly (88%) mGluR1α-expressing interneurons, which were mostly somatostatin immunopositive. Parvalbumin positive terminals were immunonegative for mGluR7a. Some parvalbumin immunoreactive dendrites received strongly mGluR7a positive terminals. The subcellular location, as well as the cell type and synapse-specific distribution of mGluR7a in isocortical neuronal circuits, is homologous to its distribution in the hippocampus. The specific location of mGluR7a in the presynaptic active zone of both glutamatergic and GABAergic synapses may be related to the proximity of calcium channels and the vesicle fusion machinery. The enrichment of mGluR7a in the main GABAergic, as well as in the glutamatergic, innervation of mGluR1α/somatostatin-expressing interneurons suggests that their activation is under unique regulation by extracellular glutamate.},
  author       = {Dalezios, Yannis and Luján, Rafael and Shigemoto, Ryuichi and Roberts, John and Somogyi, Péter},
  issn         = {1047-3211},
  journal      = {Cerebral Cortex},
  number       = {9},
  pages        = {961 -- 974},
  publisher    = {Oxford University Press},
  title        = {{Enrichment of mGluR7a in the Presynaptic active zones of GABAergic and Non-GABAergic terminals on interneurons in the rat somatosensory cortex}},
  doi          = {10.1093/cercor/12.9.961},
  volume       = {12},
  year         = {2002},
}

@article{3533,
  abstract     = {Information in neuronal networks is thought to be represented by the rate of discharge and the temporal relationship between the discharging neurons. The discharge frequency of neurons is affected by their afferents and intrinsic properties, and shows great individual variability. The temporal coordination of neurons is greatly facilitated by network oscillations. In the hippocampus, population synchrony fluctuates during theta and gamma oscillations (10-100 ms scale) and can increase almost 10-fold during sharp wave bursts. Despite these large changes in excitability in the sub-second scale, longer-term (minute-scale) firing rates of individual neurons are relatively constant in an unchanging environment. As a result, mean hippocampal output remains stable over time. To understand the mechanisms responsible for this homeostasis, we address the following issues: (i) Can firing rates of single cells be modified? (ii) Once modified, what mechanism(s) can maintain the changes? We show that firing rates of hippocampal pyramidal cells can be altered in a novel environment and by Hebbian pairing of physiological input patterns with postsynaptic burst discharge. We also illustrate a competition between single spikes and the occurrence of spike bursts. Since spike-inducing (suprathreshold) inputs decrease the ability of strong ('teaching') inputs to induce a burst discharge, we propose that the single spike versus burst competition presents a homeostatic regulatory mechanism to maintain synaptic strength and, consequently, firing rate in pyramidal cells.},
  author       = {Buzsáki, György and Csicsvari, Jozsef L and Dragoi, George and Harris, Kenneth and Henze, D. and Hirase, Hajima},
  issn         = {1047-3211},
  journal      = {Cerebral Cortex},
  number       = {9},
  pages        = {893 -- 899},
  publisher    = {Oxford University Press},
  title        = {{Homeostatic maintenance of neuronal excitability by burst discharges in vivo}},
  doi          = {10.1093/cercor/12.9.893},
  volume       = {12},
  year         = {2002},
}