@article{3799,
abstract = {GABAergic interneurones are diverse in their morphological and functional properties. Perisomatic inhibitory cells show fast spiking during sustained current injection, whereas dendritic inhibitory cells fire action potentials with lower frequency. We examined functional and molecular properties of K(+) channels in interneurones with horizontal dendrites in stratum oriens-alveus (OA) of the hippocampal CA1 region, which mainly comprise somatostatin-positive dendritic inhibitory cells. Voltage-gated K(+) currents in nucleated patches isolated from OA interneurones consisted of three major components: a fast delayed rectifier K(+) current component that was highly sensitive to external 4-aminopyridine (4-AP) and tetraethylammonium (TEA) (half-maximal inhibitory concentrations < 0.1 mM for both blockers), a slow delayed rectifier K(+) current component that was sensitive to high concentrations of TEA, but insensitive to 4-AP, and a rapidly inactivating A-type K(+) current component that was blocked by high concentrations of 4-AP, but resistant to TEA. The relative contributions of these components to the macroscopic K(+) current were estimated as 57 +/- 5, 25 +/- 6, and 19 +/- 2 %, respectively. Dendrotoxin, a selective blocker of Kv1 channels had only minimal effects on K(+) currents in nucleated patches. Coapplication of the membrane-permeant cAMP analogue 8-(4-chlorophenylthio)-adenosine 3':5'-cyclic monophosphate (cpt-cAMP) and the phosphodiesterase blocker isobutyl-methylxanthine (IBMX) resulted in a selective inhibition of the fast delayed rectifier K(+) current component. This inhibition was absent in the presence of the protein kinase A (PKA) inhibitor H-89, implying the involvement of PKA-mediated phosphorylation. Single-cell reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed a high abundance of Kv3.2 mRNA in OA interneurones, whereas the expression level of Kv3.1 mRNA was markedly lower. Similarly, RT-PCR analysis showed a high abundance of Kv4.3 mRNA, whereas Kv4.2 mRNA was undetectable. This suggests that the fast delayed rectifier K(+) current and the A-type K(+) current component are mediated predominantly by homomeric Kv3.2 and Kv4.3 channels. Selective modulation of Kv3.2 channels in OA interneurones by cAMP is likely to be an important factor regulating the activity of dendritic inhibitory cells in principal neurone-interneurone microcircuits.},
author = {Lien, Cheng-Chang and Martina, Marco and Schultz, Jobst H and Ehmke, Heimo and Peter Jonas},
journal = {Journal of Physiology},
number = {Pt 2},
pages = {405 -- 419},
publisher = {Wiley-Blackwell},
title = {{Gating, modulation and subunit composition of voltage-gated K(+) channels in dendritic inhibitory interneurones of rat hippocampus}},
doi = { 10.1113/jphysiol.2001.013066},
volume = {538},
year = {2002},
}
@article{3800,
abstract = {Networks of GABAergic interneurons are of critical importance for the generation of gamma frequency oscillations in the brain. To examine the underlying synaptic mechanisms, we made paired recordings from "basket cells" (BCs) in different subfields of hippocampal slices, using transgenic mice that express enhanced green fluorescent protein (EGFP) under the control of the parvalbumin promoter. Unitary inhibitory postsynaptic currents (IPSCs) showed large amplitude and fast time course with mean amplitude-weighted decay time constants of 2.5, 1.2, and 1.8 ms in the dentate gyrus, and the cornu ammonis area 3 (CA3) and 1 (CA1), respectively (33-34 degrees C). The decay of unitary IPSCs at BC-BC synapses was significantly faster than that at BC-principal cell synapses, indicating target cell-specific differences in IPSC kinetics. In addition, electrical coupling was found in a subset of BC-BC pairs. To examine whether an interneuron network with fast inhibitory synapses can act as a gamma frequency oscillator, we developed an interneuron network model based on experimentally determined properties. In comparison to previous interneuron network models, our model was able to generate oscillatory activity with higher coherence over a broad range of frequencies (20-110 Hz). In this model, high coherence and flexibility in frequency control emerge from the combination of synaptic properties, network structure, and electrical coupling.},
author = {Bartos, Marlene and Vida, Imre and Frotscher, Michael and Meyer, Axel and Monyer, Hannah and Geiger, Jörg R and Peter Jonas},
journal = {PNAS},
number = {20},
pages = {13222 -- 13227},
publisher = {National Academy of Sciences},
title = {{Fast synaptic inhibition promotes synchronized gamma oscillations in hippocampal interneuron networks}},
doi = {10.1073/pnas.192233099},
volume = {99},
year = {2002},
}
@article{3801,
abstract = {To examine possible interactions between fast depression and modulation of inhibitory synaptic transmission in the hippocampus, we recorded from pairs of synaptically connected basket cells (BCs) and granule cells (GCs) in the dentate gyrus of rat brain slices at 34 degrees C. Multiple-pulse depression (MPD) was examined in trains of 5 or 10 inhibitory postsynaptic currents (IPSCs) evoked at frequencies of 10-100 Hz under several conditions that inhibit transmitter release: block of voltage-dependent Ca2+ channels by Cd2+ (10 microM), activation of gamma-amino-butyric acid type B receptors (GABA(B)Rs) by baclofen (10 microM) and activation of muscarinic acetylcholine receptors (mAchRs) by carbachol (2 microM). All manipulations led to a substantial inhibition of synaptic transmission, reducing the amplitude of the first IPSC in the train (IPSC1) by 72%, 61% and 29%, respectively. However, MPD was largely preserved under these conditions (0.34 in control versus 0.31, 0.50 and 0.47 in the respective conditions at 50 Hz). Similarly, a theta burst stimulation (TBS) protocol reduced IPSC1 by 54%, but left MPD unchanged (0.40 in control and 0.39 during TBS). Analysis of both fractions of transmission failures and coefficients of variation (CV) of IPSC peak amplitudes suggested that MPD had a presynaptic expression site, independent of release probability. In conclusion, different types of presynaptic modulation of inhibitory synaptic transmission converge on a reduction of synaptic strength, while short-term dynamics are largely unchanged.},
author = {Hefft, Stefan and Kraushaar, Udo and Geiger, Jörg R and Peter Jonas},
journal = {Journal of Physiology},
number = {Pt 1},
pages = {201 -- 8},
publisher = {Wiley-Blackwell},
title = {{Presynaptic short-term depression is maintained during regulation of transmitter release at a GABAergic synapse in rat hippocampus}},
doi = {10.1113/jphysiol.2001.013455},
volume = {539},
year = {2002},
}
@article{3802,
abstract = {The presynaptic Ca2+ signal is a key determinant of transmitter release at chemical synapses. In cortical synaptic terminals, however, little is known about the kinetic properties of the presynaptic Ca2+ channels. To investigate the timing and magnitude of the presynaptic Ca2+ inflow, we performed whole-cell patch-clamp recordings from mossy fiber boutons (MFBs) in rat hippocampus. MFBs showed large high-voltage-activated Ca(2+) currents, with a maximal amplitude of approximately 100 pA at a membrane potential of 0 mV. Both activation and deactivation were fast, with time constants in the submillisecond range at a temperature of approximately 23 degrees C. An MFB action potential (AP) applied as a voltage-clamp command evoked a transient Ca2+ current with an average amplitude of approximately 170 pA and a half-duration of 580 microsec. A prepulse to +40 mV had only minimal effects on the AP-evoked Ca2+ current, indicating that presynaptic APs open the voltage-gated Ca2+ channels very effectively. On the basis of the experimental data, we developed a kinetic model with four closed states and one open state, linked by voltage-dependent rate constants. Simulations of the Ca2+ current could reproduce the experimental data, including the large amplitude and rapid time course of the current evoked by MFB APs. Furthermore, the simulations indicate that the shape of the presynaptic AP and the gating kinetics of the Ca2+ channels are tuned to produce a maximal Ca2+ influx during a minimal period of time. The precise timing and high efficacy of Ca2+ channel activation at this cortical glutamatergic synapse may be important for synchronous transmitter release and temporal information processing.},
author = {Bischofberger, Josef and Geiger, Jörg R and Peter Jonas},
journal = {Journal of Neuroscience},
number = {24},
pages = {10593 -- 10602},
publisher = {Society for Neuroscience},
title = {{Timing and efficacy of Ca(2+) channel activation in hippocampal mossy fiber boutons}},
volume = {22},
year = {2002},
}
@article{3803,
abstract = {Mossy fiber (MF) synapses are key stations for flow of information through the hippocampal formation. A major component of the output of the MF system is directed towards inhibitory interneurons. Recent studies have revealed that the functional properties of MF-interneuron synapses differ substantially from those of MF-CA3 pyramidal neuron synapses. Mossy-fiber-interneuron synapses in the stratum lucidum represent a continuum of functional subtypes, in which the subunit composition of postsynaptic AMPA receptors and NMDA receptors appears to be regulated in a coordinated manner.},
author = {Bischofberger, Josef and Peter Jonas},
journal = {Trends in Neurosciences},
number = {12},
pages = {600 -- 603},
publisher = {Elsevier},
title = {{TwoB or not twoB: differential transmission at glutamatergic mossy fiber-interneuron synapses in the hippocampus}},
doi = {10.1016/S0166-2236(02)02259-2},
volume = {25},
year = {2002},
}
@inproceedings{2340,
abstract = {
Recent experimental breakthroughs in the treatment of dilute Bose gases have renewed interest in their quantum mechanical description, respectively in approximations to it. The ground state properties of dilute Bose gases confined in external potentials and interacting via repulsive short range forces are usually described by means of the Gross-Pitaevskii energy functional. In joint work with Elliott H. Lieb and Jakob Yngvason its status as an approximation for the quantum mechanical many-body ground state problem has recently been rigorously clarified. We present a summary of this work, for both the two-and three-dimensional case.
},
author = {Robert Seiringer},
editor = {Demuth, Michael and Schultze, Bert-Wolfgang},
pages = {307 -- 314},
publisher = {Birkhäuser},
title = {{Bosons in a trap: Asymptotic exactness of the Gross-Pitaevskii ground state energy formula}},
doi = {10.1007/978-3-0348-8231-6},
volume = {126},
year = {2001},
}
@article{2341,
abstract = {We study the ground state properties of an atom with nuclear charge Z and N bosonic "electrons" in the presence of a homogeneous magnetic field B. We investigate the mean field limit N→∞ with N / Z fixed, and identify three different asymptotic regions, according to B≪Z2,B∼Z2,andB≫Z2 . In Region 1 standard Hartree theory is applicable. Region 3 is described by a one-dimensional functional, which is identical to the so-called Hyper-Strong functional introduced by Lieb, Solovej and Yngvason for atoms with fermionic electrons in the region B≫Z3 ; i.e., for very strong magnetic fields the ground state properties of atoms are independent of statistics. For Region 2 we introduce a general magnetic Hartree functional, which is studied in detail. It is shown that in the special case of an atom it can be restricted to the subspace of zero angular momentum parallel to the magnetic field, which simplifies the theory considerably. The functional reproduces the energy and the one-particle reduced density matrix for the full N-particle ground state to leading order in N, and it implies the description of the other regions as limiting cases.},
author = {Baumgartner, Bernhard and Robert Seiringer},
journal = {Annales Henri Poincare},
number = {1},
pages = {41 -- 76},
publisher = {Birkhäuser},
title = {{Atoms with bosonic "electrons" in strong magnetic fields}},
doi = {10.1007/PL00001032},
volume = {2},
year = {2001},
}
@article{2345,
abstract = {We give upper bounds for the number of spin-1/2 particles that can be bound to a nucleus of charge Z in the presence of a magnetic field B, including the spin-field coupling. We use Lieb's strategy, which is known to yield Nc < 2Z + 1 for magnetic fields that go to zero at infinity, ignoring the spin-field interaction. For particles with fermionic statistics in a homogeneous magnetic field our upper bound has an additional term of the order of Z × min {(B/Z3)2/5, 1 + | 1n(B/Z3)|2}.},
author = {Robert Seiringer},
journal = {Journal of Physics A: Mathematical and General},
number = {9},
pages = {1943 -- 1948},
publisher = {IOP Publishing Ltd.},
title = {{On the maximal ionization of atoms in strong magnetic fields}},
doi = {10.1088/0305-4470/34/9/311},
volume = {34},
year = {2001},
}
@article{2346,
abstract = {By means of a generalization of the Fefferman - de la Llave decomposition we derive a general lower bound on the interaction energy of one-dimensional quantum systems. We apply this result to a specific class of lowest Landau band wave functions.},
author = {Hainzl, Christian and Robert Seiringer},
journal = {Letters in Mathematical Physics},
number = {2},
pages = {133 -- 142},
publisher = {Springer},
title = {{Bounds on one-dimensional exchange energies with application to lowest Landau band quantum mechanics}},
doi = {10.1023/A:1010951905548},
volume = {55},
year = {2001},
}
@article{2347,
abstract = {We consider the ground state properties of an inhomogeneous two-dimensional Bose gas with a repulsive, short range pair interaction and an external confining potential. In the limit when the particle number N is large but ρ̄a2 is small, where ρ̄ is the average particle density and a the scattering length, the ground state energy and density are rigorously shown to be given to leading order by a Gross-Pitaevskii (GP) energy functional with a coupling constant g ∼ 1/| 1n(ρ̄a2)|. In contrast to the 3D case the coupling constant depends on N through the mean density. The GP energy per particle depends only on Ng. In 2D this parameter is typically so large that the gradient term in the GP energy functional is negligible and the simpler description by a Thomas-Fermi type functional is adequate.},
author = {Lieb, Élliott H and Robert Seiringer and Yngvason, Jakob},
journal = {Communications in Mathematical Physics},
number = {1},
pages = {17 -- 31},
publisher = {Springer},
title = {{A rigorous derivation of the Gross-Pitaevskii energy functional for a two-dimensional Bose gas}},
doi = {10.1007/s002200100533},
volume = {224},
year = {2001},
}