Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function

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. Gaschromatigraph of odor natural mixtures Roman Kaiser, Vom Duft der Orchideen, 1993

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

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

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

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

7. There are two olfactory systems in all animals • The pheromone system • The general odor system 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 However. these two systems are often not fully separated in function Belluscio et al. 1999

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

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

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

12. Olfactory sensillae in insects

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

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

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

17. The Nose of a fly de Bruyne 2001

18. Olfactory sensillae in flies de Bruyne 1999

19. ORNs can be grouped in classes de Bruyne 1999

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

21. 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 Or 22a Antennal Lobus Vosshall et al. 1999 Verschiedene Rezeptoren auf der Antenne

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

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

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

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

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

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

33. min DF/F max raw fluorescnece images odor induced KC signal KC dendrites KC somata Ca2+Imaging PNs and Kenyon cells selective staining of PNs and KCs Mushroom body PN boutons KC PN Antennal lobe sites of dye injection (Fura 2 dextran) PN glomeruli

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 lio lio 1-hexanol limonen linalool 2-octanol Kenyon cells max min DF/F PN boutons PN dendrites averages of 3 stimulations Paul Szyszka et al. 2005

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

37. Sparsening of the combinatorial population codes at three levels of olfactory integration 1-hexanol Kenyon cells DF/F neuropil somata PN boutons neuropil PN dendrites + lio lio max min 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% - P. Szyska et al. 2005

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

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

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

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 Ctr CS+ CS- First 3 PCs: 83% variance. 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)