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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. Natural odors are composed of many molecular components Which all have their own

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slide1

Olfaction 1

Odor as a stimulus

Olfactory receptors: Structure and function

Antennal lobe: coding odors at

the level of the primary olfactory neuropil

slide2

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

slide3

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

slide5

aber:

stark von der

Konzentration abhängig.

z.B.

Ionon (in Parfums enthalten:

niedrige Konzentration:

Veilchenduft

hohe Konzentration:

Holzduft

Roman Kaiser, 1993

Duftcharaktere

slide6

- Odor character

  • - Odor concentration
  • - Temporal structure
  • Dependence on wind
  • direction
  • Mixture effects
  • Hedonic
slide7

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

slide8

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

slide9

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

slide10

Two second messenger pathways are involved in the transduction processes

Hill, Wyse, Anderson Animal Physiology,

Sinauer, 2004

slide13

Antenna of the bee

Scapus

Pedicellus

Flagellum

Pore plates

Sensillum placodium

Lacher, 1964

v. Frisch 1965, p. 509

slide15

Extracellular recordings from placode sensilla

Two different Placode sensilla (A,B)

Akers and Getz, Chem. Senses 1992

slide16

Response spectra of different

classes of olfactory receptor

cells on the bee antenna

E. Vareschi,

Z. vergly. Physiol. 75, 143-173, 1971

the nose of a fly
The Nose of a fly

de Bruyne 2001

there are many different orn classes
There are many different ORN classes

Distribution of sensillum types on antenna

22 ORN classes in

9 types of sensilla

de Bruyne 2001

slide21

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

slide22

Coding general odors in the honey bee

Glomeruli

Antennal lobe

Antennal nerve: axons of olfactory receptor cells

slide26

Odors are coded at the level of the antennal lobe

(and the olfactory bulb) in a combinatorial pattern

of overlapping glomerular activities.

slide28

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

slide29

PTX

Ringer

?

GABA

What do these effects implicate for the AL-network?

homomeric

LI

(GABA-IR)

His

Silke Sachse,

Giovanni Galicia

slide30

-0.10

0.70

-0.12

0.53

0.93

0.31

Odor specific

patterns correlate

less in

PN measurements

slide31

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

slide32

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

ca 2 imaging pns and kenyon cells

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

slide34

Odors evoke patterns of activity increase and decrease

at the input to the mushroom body

Nobu Yamagada, unpubl. 07

odor specific combinatorial codes at three levels
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

kenyon cells respond only transiently to odors sparse time code
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 .

sparsening of the combinatorial population codes at three levels of olfactory integration
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

slide38

KN

DG

inh

N

PN

PN

KN

KN

modulatory input,

VUMmx1

microglomerulus

Organization

of the micro-

glomerulus

Jürgen Rybak

Olga Ganeshina

Dirk Müller

slide39

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

slide41

Morphological networks: Olfactory interneurons

Registration of 2 projection neurons und 1 local interneurons in the

standard atlas of the bee brain

slide42

Projection neurons

recording

site

FUA: few unit activity

110 “units”, 18% single units, 82% 2-3 units

slide43

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.

slide44

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

slide45

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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