Lecture 12 olfaction the insect antennal lobe
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Lecture 12: olfaction: the insect antennal lobe. References: H C Mulvad, thesis ( http://www.nordita.dk/~mulvad/Thesis ), Ch 2 G Laurent, Trends Neurosci 19 489-496 (1996) M Bazhenov et al, Neuron 30 553-567 and 569-581 (2001) Dayan & Abbott, Sect 7.5. Olfaction (smell).

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Lecture 12 olfaction the insect antennal lobe
Lecture 12: olfaction: the insect antennal lobe

References:

H C Mulvad, thesis (http://www.nordita.dk/~mulvad/Thesis), Ch 2

G Laurent, Trends Neurosci 19 489-496 (1996)

M Bazhenov et al, Neuron30 553-567 and 569-581 (2001)

Dayan & Abbott, Sect 7.5



Olfaction smell1
Olfaction (smell)

The oldest sense (even bacteria do it)


Olfaction smell2
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)


Olfaction smell3
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:


Olfaction smell4
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies


Olfaction smell5
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex


Olfaction smell6
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex

~100000 receptor cells, several hundred types

(distinguished by receptor proteins)


Olfaction smell7
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex

~100000 receptor cells, several hundred types

(distinguished by receptor proteins)

any cell responsive to a range of odorants:


Olfaction smell8
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex

~100000 receptor cells, several hundred types

(distinguished by receptor proteins)

any cell responsive to a range of odorants:

=> an odor produces a characteristic pattern of activity

across the receptor cell population


Olfaction smell9
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex

~100000 receptor cells, several hundred types

(distinguished by receptor proteins)

any cell responsive to a range of odorants:

=> an odor produces a characteristic pattern of activity

across the receptor cell population

Receptor physiology:

Receptor proteins (1 kind/cell): metabotropic, G-protein coupled,

lead to opening of Na channels


Olfaction smell10
Olfaction (smell)

The oldest sense (even bacteria do it)

Highly conserved in evolution (mammals and insects similar)

Basic anatomy:

Insects: receptor cells -> antennal lobe -> mushroom bodies

Mammals: receptor cells -> olfactory bulb -> olfactory cortex

~100000 receptor cells, several hundred types

(distinguished by receptor proteins)

any cell responsive to a range of odorants:

=> an odor produces a characteristic pattern of activity

across the receptor cell population

Receptor physiology:

Receptor proteins (1 kind/cell): metabotropic, G-protein coupled,

lead to opening of Na channels, similar to phototransduction

in retina


Antennal lobe
Antennal lobe

~1000-10000 neurons

in locust: 1130: 830 excitatory, 300 inhibitory

in honeybee: 800 excitatory, 4000 inhibitory


Antennal lobe1
Antennal lobe

~1000-10000 neurons

in locust: 1130: 830 excitatory, 300 inhibitory

in honeybee: 800 excitatory, 4000 inhibitory

Organized into glomeruli (bunches of synapes)

(~1000 in locust, 160 in bee)


Antennal lobe2
Antennal lobe

~1000-10000 neurons

in locust: 1130: 830 excitatory, 300 inhibitory

in honeybee: 800 excitatory, 4000 inhibitory

Organized into glomeruli (bunches of synapes)

(~1000 in locust, 160 in bee)


Antennal lobe3
Antennal lobe

~1000-10000 neurons

in locust: 1130: 830 excitatory, 300 inhibitory

in honeybee: 800 excitatory, 4000 inhibitory

Organized into glomeruli (bunches of synapes)

(~1000 in locust, 160 in bee)

Connections between AL

neurons: dendrodentritic


Excitatory cells pn
Excitatory cells (PN)

PN = projection neuron: axon takes its spikes out of the antennal

lobe, to the mushroom bodies (+ other higher areas)


Excitatory cells pn1
Excitatory cells (PN)

PN = projection neuron: axon takes its spikes out of the antennal

lobe, to the mushroom bodies (+ other higher areas)

transmitter: ACh


Excitatory cells pn2
Excitatory cells (PN)

PN = projection neuron: axon takes its spikes out of the antennal

lobe, to the mushroom bodies (+ other higher areas)

transmitter: ACh


Excitatory cells pn3
Excitatory cells (PN)

PN = projection neuron: axon takes its spikes out of the antennal

lobe, to the mushroom bodies (+ other higher areas)

transmitter: ACh

Dendrites have postsynaptic terminals

in 1 or more glomeruli

(10-20 in locust)


Inhibitory cells ln
Inhibitory cells (LN)

LN = local neuron: projects only within the antennal lobe


Inhibitory cells ln1
Inhibitory cells (LN)

LN = local neuron: projects only within the antennal lobe

no Na spikes, only Ca “spikelets”


Inhibitory cells ln2
Inhibitory cells (LN)

LN = local neuron: projects only within the antennal lobe

no Na spikes, only Ca “spikelets”

transmitter: GABA


Inhibitory cells ln3
Inhibitory cells (LN)

LN = local neuron: projects only within the antennal lobe

no Na spikes, only Ca “spikelets”

transmitter: GABA


Inhibitory cells ln4
Inhibitory cells (LN)

LN = local neuron: projects only within the antennal lobe

no Na spikes, only Ca “spikelets”

transmitter: GABA

Dendrites with postsynaptic terminals in several or all glomeruli



Antennal lobe responses temporally modulated oscillatory activity patterns1
Antennal lobe responses:temporally modulated oscillatory activity patterns

~20 hz oscillations:


Antennal lobe responses temporally modulated oscillatory activity patterns2
Antennal lobe responses:temporally modulated oscillatory activity patterns

~20 hz oscillations:

(No oscillations in input from receptor cells)


Oscillations and transient synchronization
Oscillations and transient synchronization activity patterns

membrane potentials


Oscillations and transient synchronization1
Oscillations and transient synchronization activity patterns

membrane potentials

Local field potential

In mushroom body:

Measures average

AL activity

(cell in mushroom body)


Oscillations and transient synchronization2
Oscillations and transient synchronization activity patterns

membrane potentials

Local field potential

In mushroom body:

Measures average

AL activity

(cell in mushroom body)

PN firing transiently

synchronized to

LFP


Model bazhenov et al
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs


Model bazhenov et al1
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons


Model bazhenov et al2
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons

  • (post)synaptic kinetics


Model bazhenov et al3
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons

  • (post)synaptic kinetics

  • Fast excitation, fast and slow inhibition


Model bazhenov et al4
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons

  • (post)synaptic kinetics

  • Fast excitation, fast and slow inhibition

  • 50% connectivity, random


Model bazhenov et al5
Model (Bazhenov et al) activity patterns

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons

  • (post)synaptic kinetics

  • Fast excitation, fast and slow inhibition

  • 50% connectivity, random

  • Stimuli: 1-s current pulse inputs to randomly-chosen 33% of neurons


Bazhenov network
Bazhenov network activity patterns


Excitatory neurons
Excitatory neurons activity patterns


Excitatory neurons1
Excitatory neurons activity patterns

Active currents:


Excitatory neurons2
Excitatory neurons activity patterns

Active currents:

Na


Excitatory neurons3
Excitatory neurons activity patterns

Active currents:

Na K


Excitatory neurons4
Excitatory neurons activity patterns

Active currents:

Na K A-current


Excitatory neurons5
Excitatory neurons activity patterns

Active currents:

Na K A-current

Synaptic input


Excitatory neurons6
Excitatory neurons activity patterns

Active currents:

Na K A-current

Synaptic input

Fast (ionotropic) synaptic currents (nACh and GABAA):

( [O] is open fraction)


Excitatory neurons7
Excitatory neurons activity patterns

Active currents:

Na K A-current

Synaptic input

Fast (ionotropic) synaptic currents (nACh and GABAA):

( [O] is open fraction)

[T] is transmitter concentration:


Excitatory neurons8
Excitatory neurons activity patterns

Active currents:

Na K A-current

Synaptic input

Fast (ionotropic) synaptic currents (nACh and GABAA):

( [O] is open fraction)

exc

inh

[T] is transmitter concentration:


Slow inhibition
Slow inhibition activity patterns

Kinetics like GABAB


Slow inhibition1
Slow inhibition activity patterns

Kinetics like GABAB

G-protein concentration:


Slow inhibition2
Slow inhibition activity patterns

Kinetics like GABAB

G-protein concentration:

Activated receptor concentration


Slow inhibition3
Slow inhibition activity patterns

Kinetics like GABAB

G-protein concentration:

Activated receptor concentration

Fast and slow

Components:


Inhibitory neurons
Inhibitory neurons activity patterns


Inhibitory neurons1
Inhibitory neurons activity patterns

Active currents:


Inhibitory neurons2
Inhibitory neurons activity patterns

Active currents:

Ca


Inhibitory neurons3
Inhibitory neurons activity patterns

Active currents:

Ca

( -> Ca spikes)


Inhibitory neurons4
Inhibitory neurons activity patterns

Active currents:

Ca K

( -> Ca spikes)


Inhibitory neurons5
Inhibitory neurons activity patterns

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)


Inhibitory neurons6
Inhibitory neurons activity patterns

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)

( -> spike rate adaptation)


Inhibitory neurons7
Inhibitory neurons activity patterns

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)

( -> spike rate adaptation)

Dynamics of nK(Ca):


Inhibitory neurons8
Inhibitory neurons activity patterns

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)

( -> spike rate adaptation)

Dynamics of nK(Ca):

Ca dynamics:


2 neurons 1 pn 1ln
2 neurons (1 PN, 1LN) activity patterns


6 pns 2 lns
6 PNs + 2 LNs activity patterns


6 pns 2 lns1
6 PNs + 2 LNs activity patterns

(fast) inhibition

between LNs


6 pns 2 lns2
6 PNs + 2 LNs activity patterns

(fast) inhibition

between LNs


6 pns 2 lns3
6 PNs + 2 LNs activity patterns

(fast) inhibition

between LNs

LNs take turns:


Full network 90 30
Full network (90+30) activity patterns



Responses of 4 pns to 1 stimulus1
Responses of 4 PNs to 1 stimulus activity patterns

Reliable (trial-to-trial reproducible) firing timing when there is large

Inhibitory input


Another stimulus
Another stimulus: activity patterns

Input to same set of PNs but different LNs


Another stimulus1
Another stimulus: activity patterns

Input to same set of PNs but different LNs


Another stimulus2
Another stimulus: activity patterns

Input to same set of PNs but different LNs

Same overall firing rate pattern, but different temporal fine structure


3 rd stimulus
3 activity patternsrd stimulus:

Input to 90%-different set of neurons:


3 rd stimulus1
3 activity patternsrd stimulus:

Input to 90%-different set of neurons:


3 rd stimulus2
3 activity patternsrd stimulus:

Input to 90%-different set of neurons:

Different firing pattern across neurons (but same network-average rate)


Blocking ln ln inhibition
Blocking LN-LN inhibition activity patterns

LNs now spike ~ regularly


Blocking ln ln inhibition1
Blocking LN-LN inhibition activity patterns

LNs now spike ~ regularly

Less difference between responses to stimuli 1 and 2


Reducing i k ca
Reducing I activity patternsK(Ca)

(reducing LN spike-rate adaptation)


Reducing i k ca1
Reducing I activity patternsK(Ca)

(reducing LN spike-rate adaptation)


Reducing i k ca2
Reducing I activity patternsK(Ca)

(reducing LN spike-rate adaptation)

Less precise timing, weaker temporal modulation, reduced discriminability



Role of slow ln pn inhibition1
Role of slow LN-PN inhibition activity patterns

Slow rate modulations

abolished


Role of slow ln pn inhibition2
Role of slow LN-PN inhibition activity patterns

  • Slow rate modulations

  • abolished

  • reduced

    discriminability


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