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Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function Antennal lobe: coding odors at the level of the primary olfactory neuropil.

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Präsentation zum Thema: "Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function Antennal lobe: coding odors at the level of the primary olfactory neuropil."—  Präsentation transkript:

1 Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function Antennal lobe: coding odors at the level of the primary olfactory neuropil

2 Natural odors are composed of many molecular components Which all have their own characteristic smell. The mixture of all the components usually smell very different from that of any compenent. The smell of any component or mixture can depend very much on the concentration. Roman Kaiser, Vom Duft der Orchideen, 1993 Gaschromatigraph of odor natural mixtures

3 Roman Kaiser, Vom Duft der Orchideen, 1993 Natürliche Düfte sind Gemische, deren Zusammensetzung sich ändern kann Duft der Orchidee Angraecum sesquipedale in der ersten und der zweiten Nacht des Blühens

4 Mori and Yoshihara, 1995 Substanzen, die den Jasminduft prägen

5 Roman Kaiser, 1993 aber: stark von der Konzentration abhängig. z.B. Ionon (in Parfums enthalten: niedrige Konzentration: Veilchenduft hohe Konzentration: Holzduft Duftcharaktere

6 - Odor character - Odor concentration - Temporal structure -Dependence on wind direction - Mixture effects - Hedonic

7 There are two olfactory systems in all animals Belluscio et al. 1999 -The pheromone system -The general odor system However. these two systems are often not fully separated in function For example in mammals: Pheromone system: vomero-nasal organ (VNO) Axons of the olfactory neruons projects to the accessory olfactory bulb (AOB) For general odors: main olfactory epithelium Axons of the olfactory neurons project to the Olfactory bulb

8 Rezeptoraxone Riechepithel mit ORZ Duft Mukus Zilien der ORZ Olfaktorischer Bulbus Axone der Mitralzellen Das Riechepithel von Säugetieren Olfaktorische Rezeptorzelle (ORZ) Soma der ORZ Zilie der ORZ Mukus Wahrnehmung von allgemeinen Düften Cilien Duftmoleküle

9 Duftrezeptoren in der Säugetiernase 7 Membran schleifen Odor receptor molecules are G-protein coupled receptors bei Säugern gibt es mehr als 1000 Gene für Duftrezeptoren bei Drosophila ca 50

10 Hill, Wyse, Anderson Animal Physiology, Sinauer, 2004 Two second messenger pathways are involved in the transduction processes


12 Olfactory sensillae in insects

13 v. Frisch 1965, p. 509 Antenna of the bee Scapus Pedicellus Flagellum Pore plates Sensillum placodium Lacher, 1964


15 Two different Placode sensilla (A,B) Akers and Getz, Chem. Senses 1992 Extracellular recordings from placode sensilla

16 E. Vareschi, Z. vergly. Physiol. 75, 143-173, 1971 Response spectra of different classes of olfactory receptor cells on the bee antenna

17 The Nose of a fly de Bruyne 2001

18 de Bruyne 1999 Olfactory sensillae in flies

19 ORNs can be grouped in classes de Bruyne 1999

20 There are many different ORN classes de Bruyne 2001 22 ORN classes in 9 types of sensilla Distribution of sensillum types on antenna

21 Or 22a The expression pattern of olfactory Receptor genes in Drosophila shows: -different receptor molecules are expressed in different receptor neurons -axones of recept neurons project to the same glomerulus Vosshall et al. 1999 Verschiedene Rezeptoren auf der Antenne Antennal Lobus

22 Coding general odors in the honey bee Antennal lobe Antennal nerve: axons of olfactory receptor cells Glomeruli

23 Nelken Duft

24 Oktanol


26 Odors are coded at the level of the antennal lobe (and the olfactory bulb) in a combinatorial pattern of overlapping glomerular activities.

27 Aliphatic alcohols of different carbon chain length

28 1-Octanol repetative stimulation Odor stimulation leads to both excitatory and inhibitory activity In different glomeruli Antennal lobe of the bee Odor induced Ca signals Antagonistic components shape odor coding

29 What do these effects implicate for the AL-network? Ringer PTX ? GABA His (GABA-IR) homomeric LI Silke Sachse, Giovanni Galicia

30 -0.10 -0.12 0.70 0.53 0.31 0.93 Odor specific patterns correlate less in PN measurements

31 Glomeruli von anderen zu anderen Glomeruli inhibitorische Neurone Projektionsneurone Rezeptoraxone aus Squire et al. Abb. 24.19 Die inhibitorische Verschaltung im olfakt. Bulbus/Antennallobus gleicht der in der Retina: es gibt zwei Ebenen der inhibitorischen lateralen Verschaltung Retina Olfaktor. Bulbus

32 lip: olfactory collar: visual basal ring: mixed The calyces of the mb are organized according to sensory modalities Kirschner et al. 06Wulfila Gronenburg olfactory input visual input gustatory input Schroeter and Menzel 03

33 Ca 2+ Imaging PNs and Kenyon cells PN glomeruli PN boutons KC dendrites KC somata PN KC Antennal lobe Mushroom body sites of dye injection (Fura 2 dextran) selective staining of PNs and KCs min F/F max raw fluorescnece imagesodor induced KC signal

34 Odors evoke patterns of activity increase and decrease at the input to the mushroom body Nobu Yamagada, unpubl. 07

35 Odor specific combinatorial codes at three levels 1-hexanol limonen linalool 2-octanol max min F/F averages of 3 stimulations lio Kenyon cells PN boutons PN dendrites Paul Szyszka et al. 2005

36 odor 3 s PN boutons P. Szyska et al. 2005. F/F + 1-hexanol Kenyon cells respond only transiently to odors (sparse time code) mean KC and PN responses clawed Kenyon cell projection neuron

37 Sparsening of the combinatorial population codes at three levels of olfactory integration max min 1-hexanol lio Kenyon cells PN boutons PN dendrites neuropil somata P. Szyska et al. 2005 A small proportion of the clawed Kenyon cells respond (1%). Boutons of projection neurons show excitatory and inhibitory responses. The postsynaptic sides of glomeruli (projection neurons) show excitatory and inhibitory responses. A large proportion respond: 25% F/F + -

38 inh N PN KN DG microglomerulus PN Organization of the micro- glomerulus Dirk Müller Olga Ganeshina modulatory input, VUMmx1 Jürgen Rybak

39 PN delayed inhibition release from inhibition odor Model of odor processing in the MB lip transformation of the complex temporal PN response into a binary Kenyon cell response integration whithin 200 ms local inhibition KC PN exc. PN inh. KC - - - - - - - + + + ++ + + Antennal lobe Mushroom body Paul Szyska et al. 2005 microcircuit of the lip Ganeshina, Menzel J. comp. Neurol. 2001 -


41 Registration of 2 projection neurons und 1 local interneurons in the standard atlas of the bee brain Morphological networks: Olfactory interneurons

42 Projection neurons recording site FUA: few unit activity 110 units, 18% single units, 82% 2-3 units

43 Rate response changes in the course of conditioning About equal numbers of FUAs increased and decreased rate responses (+/- stanfard deviation) More for CS+ than for CS- and Ctr. Out of 110 FUAs: 13 switched responses (mostly for CS+); 3 were recruited t o CS+, 2 did not respond to CS+ any more after conditioning.

44 PCA of rate responses and hierarchical cluster analysis (ensemble activity) starting from a 110 dimensional space First 3 PCs: 83% variance. CS+ CS- Ctr No difference if only the behavioral learners are analyzed

45 LFP changes in the course of conditioning (average of the 3 trials per animal, normalized to unit area) error bars +/- 95% (boot-strap Procedure)

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