Hörner, Michael, Prof. Dr.
Professor of Cellular Neurobiology
- Research Assistant, MPI for Ethology, Seewiesen, 1985/1986
- Dr. rer. nat., University of Göttingen, 1989
- Postdoctoral Fellow, Medical University of Kiel, Dept. Physiology, 1989 - 1990
- Assistant Professor, Institute for Zoology and Anthropology, Göttingen, 1990 - 1997
- Research Fellow Marine Biological Labs, Woods Hole, USA, 1992/1997
- Research Fellow, Arizona Research Labs, Tucson, USA, 1993/1996
- Feodor-Lynen/Humboldt Fellow, Harvard Medical School, Boston, USA, 1994 - 1995
- Habilitation (Zoology), 1997
- Associate Professor, Institute for Zoology and Anthropology, Göttingen, 1997 - 2002
- Guest Professor, University of Science & Technology, Hongkong, 2002 - 2004
- Apl. Professor, Institute for Zoology, Anthropology and Developmental Biology, Göttingen, since 2004 and Scientific Coordinator International MSc/PhD/MD-PhD Program Neurosciences
Major Research Interests
Molecular Mechanisms of Synaptic and Non-Synaptic Modulation.
Biogenic amines such as serotonin, dopamine, histamine or octopamine (OA), the pendant of norepinephrine in invertebrates, are widely distributed within the animal kingdom. These evolutionary conserved neuroactive substances are involved in the control of vital functions in both vertebrates and invertebrates. Biogenic amines often initiate long-lasting neuro-modulatory effects in their targets, which is due to diffusion following non-synaptic release activating G-protein coupled to intracellular pathways. My work is focussed on the investigation of cellular and molecular mechanisms underlying the modulation of neuronal signaling in identified networks in invertebrate model systems. Using electrophysiological, pharmacological and immunocytochemical techniques in combination with behavioral measurements, I am investigating mechanisms of aminergic modulation in identified neurons of defined networks in insects and crustacea. To address both mechanistic and functional questions, a parallel approach has been developed, which allows to investigate single identified neurons both in-vivo with intact synaptic connections and in-vitro in primary "identified" cell culture, where neurons are separated from connections to other neurons. The functional meaning of aminergic modulation on the cellular level in behaviorally-relevant circuits is assessed by quantitative behavioral measurements. The investigations show that OA enhances the responsiveness of a neuronal network in insects ("giant fiber pathway") which triggers a fast escape reaction. The reaction to sensory stimuli in the postsynaptic giant interneurons, which are monosynaptically coupled to sensory neurons via excitatory cholinergic synapses, is significantly enhanced by OA application. Characteristic changes of the action potentials in-vivo ("spike broadening") and patch-clamp recordings in-vitro suggest, that OA selectively affects slow K+-conductances in postsynaptic giant interneurons.
Selected Recent Publications
- Kloppenburg P, Hörner M (1998) Voltage-activated currents in identified giant interneurons isolated from adult crickets, Gryllus bimaculatus. J Exp Biol 201(17): 2529-2541
- Heinrich R, Cromarty S I, Hörner M, Edwards D H, Kravitz E A (1999) Autoinhibition of serotonin cells: An intrinsic regulatory mechanism sensitive to the pattern of usage of the cells. Proc Natl Acad Sci USA 96: 2473-2478
- Ferber M, Hörner M, Cepok S, Gnatzy W (2001) Digger wasp versus cricket: Mechanisms underlying the total paralysis caused by the predators venom. J Neurobiol 47: 207-2222
- Hörner, M, Heinrich, R, Cromarty, S I, Kravitz, E A (2002) Synaptic connectivity of amine-containing neurosecretory cells of lobsters: inputs to 5HT- and OCT- containing neurons. in: The Crustacean Nervous System. (ed. K. Wiese) Springer Verlag, Berlin, Heidelberg, New York, pp156-172
- Rose, T, Gras, H, Hörner, M (2006) Activity-dependent suppression of spontaneous spike generation in the Retzius neurons of the leech, Hirudo medicinalis L... Invertebrate Neuroscience 6: 169-176 (DOI 10.1007/s10158-006-0030-2)