Intrinsic and synaptic inhibition for odor coding in the...
Transcript of Intrinsic and synaptic inhibition for odor coding in the...
![Page 1: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/1.jpg)
Intrinsic and synaptic inhibition for
odor coding in the early olfactory
system
Maxim Bazhenov
University of California, Riverside
![Page 2: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/2.jpg)
Source: http://labs.seas.wustl.edu/bme/raman/research.html
A “typical” overview of the insect olfactory system
![Page 3: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/3.jpg)
Outlines
• Synaptic inhibition in the AL and
MB for odor coding
• ORN adaptation for background-
invariant odor recognition
![Page 4: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/4.jpg)
Outlines
• Synaptic inhibition in the AL and
MB for odor coding
• ORN adaptation for background-
invariant odor recognition
![Page 5: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/5.jpg)
Odor triggers oscillatory responses in the AL
Locust Moth
Ito et al., 2008
Fly
Tanaka and Stopfer 2009
Bazhenov, et al., Neuron, 2000
![Page 6: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/6.jpg)
Stopfer et al, 1997
Odor triggered AL oscillations depend on inhibition
![Page 7: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/7.jpg)
Feedback inhibition by LN provides a mechanism of PNs
phase-locking
LFP
PN
LN
GA
BAInput
nA
Ch
PN
LN
(inhibition)
![Page 8: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/8.jpg)
In the AL network model feedback inhibition by local LNs is
responsible for odor triggered oscillations
Bazhenov, et al., Neuron, 2000
![Page 9: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/9.jpg)
Feedback inhibition is a very common mechanisms of
synchronization in neural circuits.
Time when
inhibition is turned
on
Timofeev, Bazhenov, Seigneur, Sejnowski, Jasper’s basic mechanisms of
the epilepsies, 2012
For example, in the neocortex, feedback inhibition by
interneurons synchronizes principal neurons
![Page 10: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/10.jpg)
Sleep spindle oscillations
Timofeev and Bazhenov, 2005
Inhibitory
cells
![Page 11: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/11.jpg)
Spindle sequences in RE-TC network
Bazhenov et al, J Neurophys, 2000;
Bonjean at al., J Neurosci 2011, 2012
![Page 12: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/12.jpg)
Beta-gamma oscillation
The waking state of
the mammalian brain
is characterized by
the predominance of
frequencies in the
beta (15-30 Hz) and
gamma (30-80 Hz)
ranges. During slow-
wave sleep the fast
rhythms follow the
onset of depth-
negative EEG wave.
![Page 13: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/13.jpg)
Mechanisms of persistent gamma
Bazhenov & Rulkov, 2006 Time (msec)
LFP
PY
PY
IN
Inhibitory
cells
![Page 14: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/14.jpg)
Network dynamics can be quite complex
![Page 15: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/15.jpg)
In many systems feedback inhibition can
synchronize spike timing of postsynaptic cells.
What is happening in the locust AL seems to be more
complex: Different PNs become synchronized at
specific times during odor stimulation – transient
PN synchronization
![Page 16: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/16.jpg)
Transient synchronization of olfactory neurons
LFP
4 P
Ns fro
m t
he n
etw
ork 20
odor
trials
Time (in LFP cycles)
Time (cycle number)
Synchronized Non
synchronized
time
![Page 17: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/17.jpg)
In the locust AL different PNs
become synchronized at different
times during odor stimulation –
transient PN synchronization
![Page 18: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/18.jpg)
PNs are synchronized when they receive strong enough
inhibition from their LNs. The strength of inhibition may
changes over time.
Different PNs receive input
from different subsets of LNs
![Page 19: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/19.jpg)
LN-mediated inhibition to specific PN changes over time mediating transient PN synchronization
Time (cycle number)
LFP
No active LNs
1 active LN
3 active LNs
For a given PN different number
of presynaptic LNs is active at
different times of odor stimulation
GABAergic input mediated by local interneurons (LNs) mediates PN
synchronization and the transient nature of PN synchronization is
linked to variations in inhibitory drive from LNs over the duration of a
response.
![Page 20: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/20.jpg)
Simple network with 2 inhibitory neurons
Spike adaptation is responsible for
active states alternation
Assisi, Stopfer, Bazhenov Neuron,
2010
Spike adaptation No spike adaptation
![Page 21: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/21.jpg)
Dimensionality reduction
tdA
i
dt= c × f
i- A
i,
fi= F
0I
i
ext -s Ai( ),
tdA
j
dt= - A
j,
fj= 0, j = 1,.., N , j ¹ i
To describe dynamics
of the inhibitory
network, we can
define low-
dimensional
phenomenological
system for a network
of globally pulse-
coupled oscillators
Komarov and Bazhenov, in
preparation
g K (t) » A(t) = Tisi
-1(t) òt-T
isi(t )/2
t+Tisi
(t )/2
g K ( ¢t )d ¢t
![Page 22: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/22.jpg)
Phase space of 2 neuron model
Weak adaptation Strong
adaptation
![Page 23: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/23.jpg)
Definition
Graph coloring, specifically, vertex coloring of a graph
is the assignment of colors to the nodes of a graph
such that no two nodes that share an edge are
assigned the same color.
Graph coloring provides an efficient tool to describe
dynamics of the inhibitory network
![Page 24: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/24.jpg)
Increasing number of colors preserves the network
dynamics
Assisi and Bazhenov, Front Neuroeng, 2012
Connectivity matrix
Red
Green
![Page 25: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/25.jpg)
Transient activity in the network with non-unique coloring
Assisi, et al., Neuron, 2010
When multiple
colorings are
possible a group
of neurons
(highlighted) may
switch allegiance
from one
synchronous
ensemble (blue) to
another (red).
![Page 26: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/26.jpg)
Coloring–based dynamics in “random” neural
networks
Assisi, et al., Neuron, 2010
![Page 27: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/27.jpg)
Difference in the input to individual LNs leads to different
oscillatory patterns
I0
I0+DeltaI0+Delta/2
Komarov and
Bazhenov, in
preparation
![Page 28: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/28.jpg)
Ranking of the inputs to the circuits predicts order of firing
within a sequence
I0
I0+Delta1 I0+Delta2
![Page 29: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/29.jpg)
For a given odor concentration different ORNs would show
different response intensity
Intermittent
concentration
Low
concentrationHigh
concentration
Intermittent
concentration
Low
concentration
High
concentration
Input to PNsORN activation curve
Order of PN spiking for
intermittent concentration
![Page 30: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/30.jpg)
Active LNs synchronize postsynaptic PN at specific times
providing a mechanisms of transient PN synchronization
500 ms
10
Neu
ron
s0
.04
10
Neu
ron
s
LN
PN
LN
PN
During active phase
of presynaptic LNs, a
group of postsynaptic
PNs is synchronized
![Page 31: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/31.jpg)
• Feedback inhibition mediated by local interneurons (LNs) provides a mechanism for PN synchronization. Transient nature of PN synchronization is linked to variations in inhibitory drive from LNs over the duration of a response.
• Lateral inhibitory connections between LNs in the AL are responsible for complexity of LN responses during odor stimulation.
• Inhibitory networks with spike-frequency adaptation are able to discriminate different external stimuli configurations.
Conclusions
![Page 32: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/32.jpg)
PNs and KCs odor responses in vivo
Perez-Orive et al., Science 2002
16 o
dors
AL: Individual PNs MB: Individual KCs
![Page 33: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/33.jpg)
Lateral Horn Interneurons
+
We previously proposed that feed-forward inhibition from LH to
MB mediates sparseness of KCs responses
Perez-Orive, J. et al. Science 2002
Assisi, et al, Nature Neurosci, 2007
![Page 34: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/34.jpg)
LH neurons receive PN input and their activity
depends on odor concentration
Prediction: As odor concentration increases it
advances the timing of the peak of the LHI-mediated
inhibitory input thus effectively reducing the
integration window of the KCs.
Model
Assisi, at al, Nature Neurosci,
2007
![Page 35: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/35.jpg)
Adaptive inhibition limits MB response at high concentrations
In vivo
<- In vivo increase of odor
concentration leads to decrease of
KCs spiking
Model
In the model adaptive ->feedforward inhibition
reduces KCs spiking at
high concentrations
![Page 36: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/36.jpg)
Fixed size integration window does not support sparseness
The LHI phase advances as a function of increasing concentration thus
controlling the sparseness of KC activity.
![Page 37: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/37.jpg)
KCs operate as coincidence detectors for high odor
concentrations
KC
KC spikes
PN1
PN2
PNn
![Page 38: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/38.jpg)
KC
KC spikes
PN1
PN2
PNn
KCs operate as temporal integrators for low odor
concentrations
![Page 39: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/39.jpg)
Source of GABAergic inhibition to the MB calyx
Intracellular fill of GGN
shows that GABAergic
tract between LH and
MB calyx is a branch of
GGN
Gupta and Stopfer, J Neurosci, 2012
![Page 40: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/40.jpg)
GGN provides feedback inhibition to KCs that controls sparseness
of the odor representation
![Page 41: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/41.jpg)
FB inhibition can maintain low KC spike count across
concentrations
Kee at al, PLoS Comp Bio, submitted
![Page 42: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/42.jpg)
FB and FF inhibition create different phase relationships
between spiking in populations of PNs, KCs, LHNs and GGN
Kee at al, PLoS Comp Bio, submitted
![Page 43: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/43.jpg)
Conclusions
• Inhibition in the MB plays important role in
maintaining sparseness of KCs responses
• While data suggest FB nature of MB inhibition,
both FB and FF can preserve the sparseness of
KCs responses
• Only FB model provides experimentally observed
phase relationship between spiking in different
cell populations
![Page 44: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/44.jpg)
Outlines
• Synaptic inhibition in the AL for
odor coding
• ORN adaptation for background-
invariant odor recognition
![Page 45: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/45.jpg)
Natural occurrence of odors commonly involves
overlap
The natural occurrence of odors may include
simultaneous presentation of many odors.
Novel (foreground) odors may need to be identified even
in the presence of a persistent background odor.Saha at al, NN 2013
![Page 46: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/46.jpg)
Experimental set up
Background Only (Back;
BG)
Foreground Only (Fore;
FG)
FG over BG (Overlap):
Here the foreground
odor presentation
happens 2 sec after
background odor
presentation.
![Page 47: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/47.jpg)
Locust olfactory system successfully detects FG
odor in presence of BG odor
Classification
2oct-
hex
chex-
2hep
bza
ld-iaa
Saha at al, NN 2013
![Page 48: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/48.jpg)
ORNs, PNs and KCs
responses show distinct
phases: (a) On transient,
(b) Steady state, (c) Off
transient
Topically during steady
state ORNs adapt below
peak of response
![Page 49: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/49.jpg)
ORN responses during FG over BG odor
presentation
Second presentation of
the same odor leads to
largely silent ORN
response
![Page 50: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/50.jpg)
We designed kinetic model of the ORNs
I is the inactive state, O is the open state, C is the closed state.
We use mass action kinetics and an individual-based
stochastic model to simulate these transitions for each
receptor independently.
![Page 51: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/51.jpg)
Inactivation model replicates experimentally measured ORN
activity
![Page 52: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/52.jpg)
Averaging classification over time for two odors are
presented simultaneously
The model was exposed to two different odors with 3s delay between BG
and FG odor presentations
ORN mean
activity
PN population activity
Weak
Adaptation
Strong
Adaptation
![Page 53: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/53.jpg)
ORN adaptation allows FG odor to start with initial conditions
close to Baseline point
![Page 54: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/54.jpg)
Strong adaptation leads to silencing of PN responses in the
overlap between similar BG and FG odors
ORN PN activity
Different Odors Similar Odors
We
ak A
da
pta
tio
nS
tro
ng
Ad
ap
tatio
n
![Page 55: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/55.jpg)
ORN adaptation causes differential effects on classification of FG
odor presented on top of BG odor depending on the odors
similarity.
Classification
Strong Adaptation
Weak Adaptation
SimilarDifferent
Cla
ssific
ation s
uccess o
f th
e F
G o
dor
Strong
adaptation
Weak
adaptation
Similar
Different
Different
![Page 56: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/56.jpg)
Presentation of a 2d odor (FG) similar to the 1st one (BG)
leads to reduced response both in vivo and in the model
![Page 57: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/57.jpg)
Why odor overlap leads to decrease of classification
success?
PNs responding to both odors in the overlap of two similar
odors get silenced and thus the PN trajectory gets miss
oriented from foreground odor.
This effect is initiated in the ORNs by (a) adaptation
mechanism and (b) is then amplified in the AL by local
inhibition.
![Page 58: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/58.jpg)
“Illusion” - Presentation of A+B mixture (BG) followed by B+C
mixture (FG) may perceived as presentation of C alone
A
B
C
![Page 59: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/59.jpg)
![Page 60: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/60.jpg)
Conclusions
ORN adaptation can significantly
increase classification of different
odorants, by aligning overlap with
foreground trajectories.
In the case of similar odorants
adaptation has a negative effect on
classification and may lead to “illusions”
![Page 61: Intrinsic and synaptic inhibition for odor coding in the ...online.itp.ucsb.edu/online/smell15/bazhenov/pdf/Bazhenov_Smell15_… · Locust olfactory system successfully detects FG](https://reader036.fdocuments.us/reader036/viewer/2022071011/5fca0567b414e721fe5dcbb7/html5/thumbnails/61.jpg)
Lab members:
• Seth Haney
• Jen-Yung Chen
• Gregory Filatov
• Steven Skorheim
• Giri Krishnan
• Tiffany Glenn-Hall
• Mohammad Niknazar
• Oscar Gonzalez
• Paola Malerba
• Matt Choinski
• Yina Wei
• Pavel Sanda
• Timothy Myers
• Lyle Muller
• Maxim Komarov
Support:
• National Institute of Health
• Office of Naval Research (MURI)
• University of California Multicampus
Research Programs and Initiatives
Collaborators (olfaction):
• Mark Stopfer (NIH)
• Brian Smith (ASU)
• Ramon Huerta (UCSD)
• Barani Raman (U. Wash)