TY - JOUR
AB - We use the lac operon in Escherichia coli as a prototype system to illustrate the current state, applicability, and limitations of modeling the dynamics of cellular networks. We integrate three different levels of description (molecular, cellular, and that of cell population) into a single model, which seems to capture many experimental aspects of the system.
AU - Vilar,Jose M
AU - Calin Guet
AU - Leibler, Stanislas
ID - 3752
IS - 3
JF - Journal of Cell Biology
TI - Modeling network dynamics: the lac operon, a case study
VL - 161
ER -
TY - JOUR
AU - Bauer, Wolfgang
AU - Kleine-Berkenbusch, Marco
AU - Bollenbach, Tobias
ID - 3797
IS - 4
JF - Revista Mexicana De Fisica
TI - Breaking atomic nuclei into little pieces: evidence for a phase transition
VL - 49
ER -
TY - JOUR
AB - Kv3 channels are thought to be essential for the fast-spiking (FS) phenotype in GABAergic interneurons, but how these channels confer the ability to generate action potentials (APs) at high frequency is unknown. To address this question, we developed a fast dynamic-clamp system (approximately 50 kHz) that allowed us to add a Kv3 model conductance to CA1 oriens alveus (OA) interneurons in hippocampal slices. Selective pharmacological block of Kv3 channels by 0.3 mm 4-aminopyridine or 1 mm tetraethylammonium ions led to a marked broadening of APs during trains of short stimuli and a reduction in AP frequency during 1 sec stimuli. The addition of artificial Kv3 conductance restored the original AP pattern. Subtraction of Kv3 conductance by dynamic clamp mimicked the effects of the blockers. Application of artificial Kv3 conductance also led to FS in OA interneurons after complete K+ channel block and even induced FS in hippocampal pyramidal neurons in the absence of blockers. Adding artificial Kv3 conductance with altered deactivation kinetics revealed a nonmonotonic relationship between mean AP frequency and deactivation rate, with a maximum slightly above the original value. Insertion of artificial Kv3 conductance with either lowered activation threshold or inactivation also led to a reduction in the mean AP frequency. However, the mechanisms were distinct. Shifting the activation threshold induced adaptation, whereas adding inactivation caused frequency-dependent AP broadening. In conclusion, Kv3 channels are necessary for the FS phenotype of OA interneurons, and several of their gating properties appear to be optimized for high-frequency repetitive activity.
AU - Lien, Cheng-Chang
AU - Peter Jonas
ID - 3804
IS - 6
JF - Journal of Neuroscience
TI - Kv3 potassium conductance is necessary and kinetically optimized for high-frequency action potential generation in hippocampal interneurons
VL - 23
ER -
TY - JOUR
AB - To probe exocytosis at a cortical glutamatergic synapse, we made capacitance measurements in whole-cell recorded hippocampal mossy fiber terminals. Evaluation of different methods by using a morphology-based equivalent electrical model revealed that quantitative capacitance measurements are possible in this presynaptic structure. Voltage pulses leading to presynaptic Ca2+ inflow evoked large capacitance signals that showed saturation with increasing pulse duration. The mean peak capacitance increase was 100 fF, corresponding to a pool of approximately 1,400 releasable vesicles. Thus hippocampal mossy fiber synapses have a vesicular "maxipool." Large pool size and rapid vesicle recycling may underlie the uniquely large extent of activity-dependent plasticity in this synapse.
AU - Hallermann, Stefan
AU - Pawlu, Christian
AU - Peter Jonas
AU - Heckmann, Manfred
ID - 3806
IS - 15
JF - PNAS
TI - A large pool of releasable vesicles in a cortical glutamatergic synapse
VL - 100
ER -
TY - CONF
AB - Many verification, planning, and control problems can be modeled as games played on state-transition graphs by one or two players whose conflicting goals are to form a path in the graph. The focus here is on simple stochastic parity games, that is, two-player games with turn-based probabilistic transitions and omega-regular objectives formalized as parity (Rabin chain) winning conditions. An efficient translation from simple stochastic parity games to nonstochastic parity games is given. As many algorithms are known for solving the latter, the translation yields efficient algorithms for computing the states of a simple stochastic parity game from which a player can win with probability 1. An important special case of simple stochastic parity games are the Markov decision processes with Buchi objectives. For this special case a first provably subquadratic algorithm is given for computing the states from which the single player has a strategy to achieve a Buchi objective with probability 1. For game graphs with m edges the algorithm works in time O(mrootm). Interestingly, a similar technique sheds light on the question of the computational complexity of solving simple Buchi games and yields the first provably subquadratic algorithm, with a running time of O(n(2)/log n) for game graphs with n vertices and O(n) edges.
AU - Krishnendu Chatterjee
AU - JurdziĆski, Marcin
AU - Thomas Henzinger
ID - 3897
TI - Simple stochastic parity games
VL - 2803
ER -