March 29, 1994 - March 29, 2027

  • Date:23MondaySeptember 2019

    Tonic GABAA receptor mediated conductance at cellular and network levels

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    Time
    14:00 - 15:00
    Location
    Nella and Leon Benoziyo Building for Brain Research
    Lecturer
    Prof. Alexey Semyanov
    Head, Dept of Molecular Neurobiology, Institute of BioOrganic Chemistry, Moscow
    Organizer
    Department of Brain Sciences
    Contact
    DetailsShow full text description of Benoziyo Brain Research Building Room 113 Host: Prof. M...»
    Benoziyo Brain Research Building Room 113

    Host: Prof. Menahem Segal menahem.segal@weizmann.ac.il tel: 2553

    For assistance with accessibility issues, please contact naomi.moses@weizmann.ac.il
    AbstractShow full text abstract about GABAA receptors mediate two forms of signaling in the brain:...»
    GABAA receptors mediate two forms of signaling in the brain: phasic and tonic. Phasic signaling (e.g., IPSCs) is mediated by synaptic GABAA receptors, while tonic signaling (e.g., tonic current or tonic conductance) is mediated by extrasynaptic GABAA receptors. Tonic current is expressed in a cell-type specific manner and is mediated by heterogeneous and plastic GABAA receptors. These receptors are activated by ambient GABA that originates from vesicular and non-vesicular sources and is regulated by different GABA transporter systems.
    Tonic GABAA conductance is commonly referred as tonic inhibition. We found that ambient GABA can actually excite adult hippocampal interneurons. In these cells, the GABAA reversal potential is depolarizing, making baseline tonic GABAA conductance excitatory. Increasing the tonic conductance enhances shunting-mediated inhibition, which eventually overpowers the excitation. Because hippocampal interneurons are the key to setting the network rhythms this mechanism allows bidirectional control of network synchronization by tonic GABAA receptor-mediated signaling.
    We also show that tonic GABAA conductance decreases the membrane time constant (τm) and improves the temporal fidelity of EPSP-spike coupling. Long-term potentiation (LTP) induced by different stimulation patterns is differently affected by tonic GABAA conductance.
    Our findings thus point to an important role of extrasynaptic signaling mediated by GABAA receptors in brain computations.
    Lecture