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

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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 smell

Olfaction (smell)


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 patterns

Antennal lobe responses:temporally modulated oscillatory activity patterns


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

membrane potentials


Oscillations and transient synchronization1

Oscillations and transient synchronization

membrane potentials

Local field potential

In mushroom body:

Measures average

AL activity

(cell in mushroom body)


Oscillations and transient synchronization2

Oscillations and transient synchronization

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)

  • 90 PNs, 30 LNs


Model bazhenov et al1

Model (Bazhenov et al)

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons


Model bazhenov et al2

Model (Bazhenov et al)

  • 90 PNs, 30 LNs

  • Single-compartment, conductance-based neurons

  • (post)synaptic kinetics


Model bazhenov et al3

Model (Bazhenov et al)

  • 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)

  • 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)

  • 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


Excitatory neurons

Excitatory neurons


Excitatory neurons1

Excitatory neurons

Active currents:


Excitatory neurons2

Excitatory neurons

Active currents:

Na


Excitatory neurons3

Excitatory neurons

Active currents:

Na K


Excitatory neurons4

Excitatory neurons

Active currents:

Na K A-current


Excitatory neurons5

Excitatory neurons

Active currents:

Na K A-current

Synaptic input


Excitatory neurons6

Excitatory neurons

Active currents:

Na K A-current

Synaptic input

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

( [O] is open fraction)


Excitatory neurons7

Excitatory neurons

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

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

Kinetics like GABAB


Slow inhibition1

Slow inhibition

Kinetics like GABAB

G-protein concentration:


Slow inhibition2

Slow inhibition

Kinetics like GABAB

G-protein concentration:

Activated receptor concentration


Slow inhibition3

Slow inhibition

Kinetics like GABAB

G-protein concentration:

Activated receptor concentration

Fast and slow

Components:


Inhibitory neurons

Inhibitory neurons


Inhibitory neurons1

Inhibitory neurons

Active currents:


Inhibitory neurons2

Inhibitory neurons

Active currents:

Ca


Inhibitory neurons3

Inhibitory neurons

Active currents:

Ca

( -> Ca spikes)


Inhibitory neurons4

Inhibitory neurons

Active currents:

Ca K

( -> Ca spikes)


Inhibitory neurons5

Inhibitory neurons

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)


Inhibitory neurons6

Inhibitory neurons

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)

( -> spike rate adaptation)


Inhibitory neurons7

Inhibitory neurons

Active currents:

Ca K Ca-dependent K current

( -> Ca spikes)

( -> spike rate adaptation)

Dynamics of nK(Ca):


Inhibitory neurons8

Inhibitory neurons

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)


6 pns 2 lns

6 PNs + 2 LNs


6 pns 2 lns1

6 PNs + 2 LNs

(fast) inhibition

between LNs


6 pns 2 lns2

6 PNs + 2 LNs

(fast) inhibition

between LNs


6 pns 2 lns3

6 PNs + 2 LNs

(fast) inhibition

between LNs

LNs take turns:


Full network 90 30

Full network (90+30)


Responses of 4 pns to 1 stimulus

Responses of 4 PNs to 1 stimulus


Responses of 4 pns to 1 stimulus1

Responses of 4 PNs to 1 stimulus

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

Inhibitory input


Another stimulus

Another stimulus:

Input to same set of PNs but different LNs


Another stimulus1

Another stimulus:

Input to same set of PNs but different LNs


Another stimulus2

Another stimulus:

Input to same set of PNs but different LNs

Same overall firing rate pattern, but different temporal fine structure


3 rd stimulus

3rd stimulus:

Input to 90%-different set of neurons:


3 rd stimulus1

3rd stimulus:

Input to 90%-different set of neurons:


3 rd stimulus2

3rd 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

LNs now spike ~ regularly


Blocking ln ln inhibition1

Blocking LN-LN inhibition

LNs now spike ~ regularly

Less difference between responses to stimuli 1 and 2


Reducing i k ca

Reducing IK(Ca)

(reducing LN spike-rate adaptation)


Reducing i k ca1

Reducing IK(Ca)

(reducing LN spike-rate adaptation)


Reducing i k ca2

Reducing IK(Ca)

(reducing LN spike-rate adaptation)

Less precise timing, weaker temporal modulation, reduced discriminability


Role of slow ln pn inhibition

Role of slow LN-PN inhibition


Role of slow ln pn inhibition1

Role of slow LN-PN inhibition

Slow rate modulations

abolished


Role of slow ln pn inhibition2

Role of slow LN-PN inhibition

  • Slow rate modulations

  • abolished

  • reduced

    discriminability


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