Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function Antennal lobe: coding...
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Transcript of Olfaction 1 Odor as a stimulus Olfactory receptors: Structure and function Antennal lobe: coding...
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 componentsWhich all have their own characteristic smell.The mixture of all the componentsusually smell very different fromthat of any compenent.
The smell of any component ormixture can depend very much on the concentration.
Roman Kaiser, Vom Duft der Orchideen, 1993
Gaschromatigraph of odor natural mixtures
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
Mori and Yoshihara, 1995
Substanzen, die den Jasminduft prägen
Roman Kaiser, 1993
aber:stark von der Konzentration abhängig.
z.B.Ionon (in Parfums enthalten:niedrige Konzentration: Veilchendufthohe Konzentration: Holzduft
Duftcharaktere
- Odor character- Odor concentration- Temporal structure-Dependence on wind direction- Mixture effects- Hedonic
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 fullyseparated in function
For example in mammals:Pheromone system: vomero-nasal organ (VNO)Axons of the olfactory neruons projectsto the accessory olfactory bulb (AOB)
For general odors: main olfactory epitheliumAxons of the olfactory neurons project to theOlfactory bulb
Rezeptoraxone
Riechepithelmit ORZ
Duft
Mukus
Zilien derORZ
OlfaktorischerBulbus
Axone der Mitralzellen
Das Riechepithel von Säugetieren
OlfaktorischeRezeptorzelle(ORZ)
Soma derORZ
Zilie der ORZ
Mukus
Wahrnehmung von allgemeinen Düften
Cilien
Duftmoleküle
Duftrezeptoren in der Säugetiernase
7 Membran schleifen
Odor receptor molecules are G-protein coupled receptors
bei Säugern gibt es mehr als 1000 Genefür Duftrezeptorenbei Drosophilaca 50
Hill, Wyse, Anderson Animal Physiology, Sinauer, 2004
Two second messenger pathways are involved in the transduction processes
Olfactory sensillae in insects
v. Frisch 1965, p. 509
Antenna of the beeScapus
Pedicellus
Flagellum
Pore platesSensillum placodium
Lacher, 1964
Two different Placode sensilla (A,B)
Akers and Getz, Chem. Senses 1992
Extracellular recordings from placode sensilla
E. Vareschi, Z. vergly. Physiol. 75, 143-173, 1971
Response spectra of differentclasses of olfactory receptorcells on the bee antenna
The Nose of a fly
de Bruyne 2001
de Bruyne 1999
Olfactory sensillae in flies
ORNs can be grouped in classes
de Bruyne 1999
There are many different ORN classes
de Bruyne 2001
22 ORN classes in 9 types of sensilla
Distribution of sensillum types on antenna
Or 22a
The expression pattern of olfactoryReceptor 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
AntennalLobus
Coding general odors in the honey bee
Antennal lobe
Antennal nerve: axons of olfactory receptor cells
Glomeruli
Nelken Duft
Oktanol
Odors are coded at the level of the antennal lobe (and the olfactory bulb) in a combinatorial patternof overlapping glomerular activities.
Aliphatic alcohols of different carbon chain length
1-Octanolrepetativestimulation
QuickTime™ and a decompressor
are needed to see this picture.
Odor stimulation leads to bothexcitatory and inhibitory activityIn different glomeruli
Antennal lobe of the beeOdor induced Ca signals
Antagonistic components shape odor coding
What do these effects implicate for the AL-network?
Ringer
PTX
?
GABA
His
(GABA-IR)
homomericLI
Silke Sachse, Giovanni Galicia
-0.10
-0.12
0.70
0.53
0.31
0.93
Odor specific patterns correlate less inPN measurements
Glomeruli
von anderen
zu anderenGlomeruli
inhibitorischeNeurone
Projektionsneurone
Rezeptoraxone
aus Squire et al. Abb. 24.19
Die inhibitorische Verschaltung imolfakt. Bulbus/Antennallobus gleichtder in der Retina: es gibt zwei Ebenen derinhibitorischen lateralen Verschaltung
Retina
Olfaktor. Bulbus
lip: olfactory
collar:visual
basalring:mixed
The calyces of the mb are organized according to sensory modalities
Kirschner et al. 06 Wulfila Gronenburg
olfactory inputvisual input
gustatory input
Schroeter and Menzel 03
Ca2+ Imaging PNs and Kenyon cells
PN glomeruli
PN boutons
KC dendrites
KC somata
PN
KC
Antennallobe
Mushroom body
sites of dye injection(Fura 2 dextran)
selective staining ofPNs and KCs
min F/F max
raw fluorescnece images odor induced KC signal
Odors evoke patterns of activity increase and decreaseat the input to the mushroom body
Nobu Yamagada, unpubl. 07
Odor specific combinatorial codes at three levels
1-hexanol limonen linalool 2-octanolmax
min
F/F
averages of 3 stimulations
lio
lioKenyon cells
PN boutons
PN dendrites
Paul Szyszka et al. 2005
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
projectionneuron
Sparsening of the combinatorial population codes at three levels of olfactory integration
max
min
1-hexanol
lio
lioKenyon cells
PN boutons
PN dendrites
neuropil
neuropilsomata
P. Szyska et al. 2005
A small proportion of the clawedKenyon cells respond (1%).
Boutons of projection neuronsshow excitatory and inhibitoryresponses.
The postsynaptic sides of glomeruli(projection neurons) show excitatory and inhibitory responses. A large proportion respond: 25%
F/F
+
-
inhN
PN
KN
KN
KN
DG
microglomerulus
PN
Organizationof the micro-glomerulus
Dirk Müller
Olga Ganeshinamodulatory input,VUMmx1
Jürgen Rybak
PN
delayedinhibition
release frominhibition
odor
Model of odor processing in the MB lip
• transformation of the complex temporal PN response into a binary Kenyon cell response
integrationwhithin 200 ms
localinhibition
KCPN exc.PN inh.
KC
-- ---
- -+
++ + +
+
+Antennallobe
Mushroom body
Paul Szyska et al. 2005
microcircuit of the lip
Ganeshina, MenzelJ. comp. Neurol. 2001
-
Registration of 2 projection neurons und 1 local interneurons in the standard atlas of the bee brain
Morphological networks: Olfactory interneurons
Projection neurons
recordingsite
FUA: few unit activity 110 “units”, 18% single units, 82% 2-3 units
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.
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
LFP changes in the course of conditioning(average of the 3 trials per animal, normalized to unit area)
error bars+/- 95%(boot-strapProcedure)