Transcript PN - Institut für Biologie Neurobiologie

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
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
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
Substanzen, die den Jasminduft prägen
Mori and Yoshihara, 1995
Duftcharaktere
aber:
stark von der
Konzentration abhängig.
z.B.
Ionon (in Parfums enthalten:
niedrige Konzentration:
Veilchenduft
hohe Konzentration:
Holzduft
Roman Kaiser, 1993
- Odor character
- Odor concentration
- Temporal structure
-Dependence on wind
direction
- Mixture effects
- Hedonic
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
Das Riechepithel von Säugetieren
Duft
Duftmoleküle
Mukus
Zilien der
ORZ
Riechepithel
mit ORZ
Cilien
Mukus
Rezeptoraxone
Olfaktorische
Rezeptorzelle
(ORZ)
Soma der
ORZ
Zilie
der ORZ
Wahrnehmung von allgemeinen Düften
Olfaktorischer
Bulbus
Axone der
Mitralzellen
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
Two second messenger pathways are involved in the transduction processes
Hill, Wyse, Anderson Animal Physiology,
Sinauer, 2004
Olfactory sensillae in insects
Antenna of the bee
Scapus
Pedicellus
Flagellum
Pore plates
Sensillum placodium
Lacher, 1964
v. Frisch 1965, p. 509
Extracellular recordings from placode sensilla
Two different Placode sensilla (A,B)
Akers and Getz, Chem. Senses 1992
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
de Bruyne 2001
Olfactory sensillae in flies
de Bruyne 1999
ORNs can be grouped in classes
de Bruyne 1999
There are many different ORN
classes
Distribution of sensillum types on antenna
22 ORN classes in
9 types of sensilla
de Bruyne 2001
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
Coding general odors in the honey bee
Glomeruli
Antennal lobe
Antennal nerve: axons of olfactory receptor cells
Nelken Duft
Oktanol
Odors are coded at the level of the antennal lobe
(and the olfactory bulb) in a combinatorial pattern
of overlapping glomerular activities.
Aliphatic alcohols of different carbon chain length
Antagonistic components shape odor coding
Odor stimulation leads to both
excitatory and inhibitory activity
In different glomeruli
QuickTime™ and a
decompressor
are needed to see this picture.
1-Octanol
repetative
stimulation
Antennal lobe of the bee
Odor induced Ca signals
What do these effects implicate for the AL-network?
PTX
Ringer
homomeric
LI
(GABA-IR)
His
?
GABA
Silke Sachse,
Giovanni Galicia
Odor specific
patterns correlate
less in
PN measurements
-0.10
0.70
-0.12
0.53
0.93
0.31
Retina
Die inhibitorische Verschaltung im
olfakt. Bulbus/Antennallobus gleicht
der in der Retina: es gibt zwei Ebenen der
inhibitorischen lateralen Verschaltung
Rezeptoraxone
von anderen
Olfaktor. Bulbus
Glomeruli
zu anderen
Glomeruli
inhibitorische
Neurone
Projektionsneurone
aus Squire et al. Abb. 24.19
The calyces of the mb are organized according to sensory modalities
olfactory input
lip: olfactory
visual input
basal
ring:
mixed
collar:
visual
gustatory input
Schroeter and Menzel 03
Kirschner et al. 06
Wulfila Gronenburg
Ca2+ Imaging PNs and Kenyon cells
raw fluorescnece images
selective staining of
PNs and KCs
KC dendrites
KC somata
Mushroom
body
PN boutons
KC
PN
Antennal
lobe
sites of dye injection
(Fura 2 dextran)
PN
min DF/F max
glomeruli
odor induced KC signal
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
1-hexanol
limonen
linalool
2-octanol
max
DF/F
Kenyon cells
lio
min
PN boutons
lio
PN dendrites
Paul Szyszka et al. 2005
averages of 3 stimulations
Kenyon cells respond only transiently to odors
(sparse time code)
clawed Kenyon cell
PN
boutons
projection
neuron
mean KC
and PN responses
3s
1-hexanol
odor
+
DF/F
P. Szyska et al. 2005 .
Sparsening of the combinatorial population codes at
three levels of olfactory integration
Kenyon cells
lio
1-hexanol
A small proportion of the clawed
Kenyon cells respond (1%).
somata
neuropil
PN boutons
lio
-
DF/F
neuropil
+
PN dendrites
P. Szyska et al. 2005
max
min
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%
Organization
of the microglomerulus
Jürgen Rybak
KN
KN
DG
PN
inh
N
KN
microglomerulus
modulatory input,
VUMmx1
Dirk Müller
Olga Ganeshina
Model of odor processing in the MB lip
odor
Mushroom body
local
inhibition
+
Antennal
lobe
+
+
+ +
- +-+
- PN
integration
whithin
200 ms
delayed
inhibition
release from
inhibition
KC
• transformation of the complex
temporal PN response into a binary
Kenyon cell response
microcircuit
of the lip
Ganeshina, Menzel
J. comp. Neurol. 2001
KC
PN exc.
PN inh.
Paul Szyska et al. 2005
Morphological networks: Olfactory interneurons
Registration of 2 projection neurons und 1 local interneurons in the
standard atlas of the bee brain
Projection neurons
recording
site
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
Ctr
CS+
CS-
First 3 PCs: 83% variance.
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-strap
Procedure)