Cellular and Network Mechanisms in the Kindling Model of Epilepsy: The Role of GABAergic Inhibition and the Emergence of Strange Attractors

1990 ◽  
pp. 115-139 ◽  
Author(s):  
Fernando H. Lopes Da Silva ◽  
Willem Kamphuis ◽  
Jan M. A. M. Van Neerven ◽  
Jan Pieter M. Pijn
Keyword(s):  
Strange Attractors ◽  
Gabaergic Inhibition ◽  
Kindling Model

Strange Attractors and Chaos in Nonlinear Mechanics

1983 ◽  
Vol 50 (4b) ◽  
pp. 1021-1032 ◽  
Author(s):  
P. J. Holmes ◽  
F. C. Moon
Keyword(s):  
Mathematical Models ◽  
Initial Conditions ◽  
Piecewise Linear ◽  
Nonlinear Differential Equations ◽  
Homoclinic Orbits ◽  
Strange Attractors ◽  
Electrical Systems ◽  
Nonlinear Mechanical ◽  
Sensitive Dependence

We review several examples of nonlinear mechanical and electrical systems and related mathematical models that display chaotic dynamics or strange attractors. Some simple mathematical models — iterated piecewise linear mappings — are introduced to explain and illustrate the concepts of sensitive dependence on initial conditions and chaos. In particular, we describe the role of homoclinic orbits and the horseshoe map in the generation of chaos, and indicate how the existence of such features can be detected in specific nonlinear differential equations.

Role of GABAergic Inhibition in the Coding of Interaural Time Differences of Low-Frequency Sounds in the Inferior Colliculus

2005 ◽  
Vol 93 (6) ◽  
pp. 3390-3400 ◽  
Author(s):  
W. R. D’Angelo ◽  
S. J. Sterbing ◽  
E.-M. Ostapoff ◽  
S. Kuwada
Keyword(s):  
Inferior Colliculus ◽  
Signal To Noise Ratio ◽  
Interaural Time Difference ◽  
Low Frequency ◽  
Gabaergic Inhibition ◽  
Interaural Time Differences ◽  
Gaba Antagonists ◽  
Inhibitory Transmitter ◽  
Almost All

A major cue for the localization of sound in space is the interaural time difference (ITD). We examined the role of inhibition in the shaping of ITD responses in the inferior colliculus (IC) by iontophoretically ejecting γ-aminobutyric acid (GABA) antagonists and GABA itself using a multibarrel pipette. The GABA antagonists block inhibition, whereas the applied GABA provides a constant level of inhibition. The effects on ITD responses were evaluated before, during and after the application of the drugs. If GABA-mediated inhibition is involved in shaping ITD tuning in IC neurons, then applying additional amounts of this inhibitory transmitter should alter ITD tuning. Indeed, for almost all neurons tested, applying GABA reduced the firing rate and consequently sharpened ITD tuning. Conversely, blocking GABA-mediated inhibition increased the activity of IC neurons, often reduced the signal-to-noise ratio and often broadened ITD tuning. Blocking GABA could also alter the shape of the ITD function and shift its peak suggesting that the role of inhibition is multifaceted. These effects indicate that GABAergic inhibition at the level of the IC is important for ITD coding.

STRANGE ATTRACTORS, KINEMATIC TRAJECTORIES AND SYNCHRONIZATION

2008 ◽  
Vol 18 (12) ◽  
pp. 3703-3718 ◽  
Author(s):  
LUIGI FORTUNA ◽  
MATTIA FRASCA ◽  
CRISTOFORO CAMERANO
Keyword(s):  
Control Systems ◽  
Cooperative Behavior ◽  
Chaotic Synchronization ◽  
Emergent Behavior ◽  
Strange Attractors ◽  
Mechanical Control ◽  
Inspection Robots

In this communication the emergent behavior of clusters of robots with chaotic kinematics attractors is shown. Even if the aim of the research started from the study of the cooperative behavior of inspection robots, the reported results (including also the role of chaotic synchronization in the generation of the kinematics trajectory), show new aesthetic features of the motion in mechanical control systems.

scholarly journals BDNF-induced TrkB activation down-regulates the K+–Cl− cotransporter KCC2 and impairs neuronal Cl− extrusion

2002 ◽  
Vol 159 (5) ◽  
pp. 747-752 ◽  
Author(s):  
Claudio Rivera ◽  
Hong Li ◽  
Judith Thomas-Crusells ◽  
Hannele Lahtinen ◽  
Tero Viitanen ◽  
...  
Keyword(s):  
Hippocampal Slice ◽  
Neuronal Excitability ◽  
Epileptic Activity ◽  
Signaling Cascades ◽  
Gabaergic Inhibition ◽  
Long Term Effects ◽  
Mouse Hippocampus

Pathophysiological activity and various kinds of traumatic insults are known to have deleterious long-term effects on neuronal Cl− regulation, which can lead to a suppression of fast postsynaptic GABAergic responses. Brain-derived neurotrophic factor (BDNF) increases neuronal excitability through a conjunction of mechanisms that include regulation of the efficacy of GABAergic transmission. Here, we show that exposure of rat hippocampal slice cultures and acute slices to exogenous BDNF or neurotrophin-4 produces a TrkB-mediated fall in the neuron-specific K+–Cl− cotransporter KCC2 mRNA and protein, as well as a consequent impairment in neuronal Cl− extrusion capacity. After kindling-induced seizures in vivo, the expression of KCC2 is down-regulated in the mouse hippocampus with a spatiotemporal profile complementary to the up-regulation of TrkB and BDNF. The present data demonstrate a novel mechanism whereby BDNF/TrkB signaling suppresses chloride-dependent fast GABAergic inhibition, which most likely contributes to the well-known role of TrkB-activated signaling cascades in the induction and establishment of epileptic activity.

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