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Synaptic Physiology of the Retina

PI: Norbert Babai

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Issue

The retina with its millions of neurons interconnected by billions of electrical and chemical synapses processes and analyses key aspects of visual information. The first synapse in visual signal processing is the photoreceptor ribbon synapse, a highly complex chemical synapse specialized for the fast and continuous release of glutamate onto postsynaptic bipolar and horizontal cells.

Focus

In my research, I try to decipher photoreceptor ribbon synaptic function. More specifically, I want to understand how the different components of the synaptic machinery, e.g. the synaptic ribbon, synaptic vesicles, voltage-sensitive Ca2+ channels, pre- and postsynaptic neurotransmitter receptors, synaptic regulatory proteins etc. contribute to the sophisticated performance of the synapse in the adult and the developing retina.

Methods

Preparations include retinal slices and whole mount retinae from adult and postnatal developing mice. In my experiments, I employ a variety of different electrophysiological and imaging techniques. Electrophysiological experiments involve whole cell patch clamp technique in current and voltage clamp mode and light and electric stimulation of the photoreceptors. Imaging experiments include Ca2+ imaging with single wavelength and ratiometric Ca2+ dyes, laser scanning confocal microscopy, two photon and electron microscopy.

Selected Publications

  • Babai N, Gierke K, Müller T, Regus-Leidig H, Brandstätter JH, Feigenspan A. (2018) Signal transmission at invaginating cone photoreceptor synaptic contacts following deletion of the presynaptic cytomatrix protein Bassoon in mouse retina. Acta Physiol (Oxf). e13241.
  • Löhner M, Babai N, Müller T, Gierke K, Atorf J, Joachimsthaler A, Peukert A, Martens H, Feigenspan A, Kremers J, Schoch S, Brandstätter JH, Regus-Leidig H. (2017) Analysis of RIM Expression and Function at Mouse Photoreceptor Ribbon Synapses. J Neurosci. 37(33):7848-7863.
  • Babai N, Sendelbeck A, Regus-Leidig H, Fuchs M, Mertins J, Reim K, Brose N, Feigenspan A, Brandstätter JH. (2016) Functional Roles of Complexin3 and Complexin4 at Mouse Photoreceptor Ribbon Synapses. J. Neurosci. 36(25):6651-67.
  • Kochubey O, Babai N, Schneggenburger R. (2016) A Synaptotagmin Isoform Switch during the Development of an Identified CNS Synapse. Neuron. 90(5):984-99.
  • Feigenspan A, Babai N. (2015) Functional properties of spontaneous excitatory currents and encoding of light/dark transitions in horizontal cells of the mouse retina. Eur J Neurosci. 42(9):2615-32.
  • Babai N, Kochubey O, Keller D, Schneggenburger R. (2014) An alien divalent ion reveals a major role for Ca²⁺ buffering in controlling slow transmitter release. J Neurosci. 34(38):12622-35.
  • Michalski N, Babai N, Renier N, Perkel DJ, Chédotal A, Schneggenburger R. (2013) Robo3-driven axon midline crossing conditions functional maturation of a large commissural synapse. Neuron. 78(5):855-68.
  • Snellman J, Mehta B, Babai N, Bartoletti TM, Akmentin W, Francis A, Matthews G, Thoreson WB, Zenisek D. (2011) Acute destruction of the synaptic ribbon reveals a role for the ribbon in vesicle priming. Nat Neurosci. 14(9):1135-41.
  • Babai N, Bartoletti TM, Thoreson WB. (2010) Calcium regulates vesicle replenishment at the cone ribbon synapse. J Neurosci. 30(47):15866-77.
  • Babai N, Morgans CW, Thoreson WB. (2010) Calcium-induced calcium release contributes to synaptic release from mouse rod photoreceptors. Neuroscience. 165(4):1447-56.
  • Babai N, Thoreson WB. (2009) Horizontal cell feedback regulates calcium currents and intracellular calcium levels in rod photoreceptors of salamander and mouse retina. J. Physiol. (Lond.), 587(Pt 10):2353-2364.

Publications in PubMed