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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, 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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  1. 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

  2. Olfaction (smell)

  3. Olfaction (smell) The oldest sense (even bacteria do it)

  4. Olfaction (smell) The oldest sense (even bacteria do it) Highly conserved in evolution (mammals and insects similar)

  5. Olfaction (smell) The oldest sense (even bacteria do it) Highly conserved in evolution (mammals and insects similar) Basic anatomy:

  6. 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

  7. 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

  8. 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)

  9. 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:

  10. 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

  11. 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

  12. 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

  13. Antennal lobe ~1000-10000 neurons in locust: 1130: 830 excitatory, 300 inhibitory in honeybee: 800 excitatory, 4000 inhibitory

  14. 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)

  15. 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)

  16. 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

  17. Excitatory cells (PN) PN = projection neuron: axon takes its spikes out of the antennal lobe, to the mushroom bodies (+ other higher areas)

  18. Excitatory cells (PN) PN = projection neuron: axon takes its spikes out of the antennal lobe, to the mushroom bodies (+ other higher areas) transmitter: ACh

  19. Excitatory cells (PN) PN = projection neuron: axon takes its spikes out of the antennal lobe, to the mushroom bodies (+ other higher areas) transmitter: ACh

  20. 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)

  21. Inhibitory cells (LN) LN = local neuron: projects only within the antennal lobe

  22. Inhibitory cells (LN) LN = local neuron: projects only within the antennal lobe no Na spikes, only Ca “spikelets”

  23. Inhibitory cells (LN) LN = local neuron: projects only within the antennal lobe no Na spikes, only Ca “spikelets” transmitter: GABA

  24. Inhibitory cells (LN) LN = local neuron: projects only within the antennal lobe no Na spikes, only Ca “spikelets” transmitter: GABA

  25. 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

  26. Antennal lobe responses:temporally modulated oscillatory activity patterns

  27. Antennal lobe responses:temporally modulated oscillatory activity patterns ~20 hz oscillations:

  28. Antennal lobe responses:temporally modulated oscillatory activity patterns ~20 hz oscillations: (No oscillations in input from receptor cells)

  29. Oscillations and transient synchronization membrane potentials

  30. Oscillations and transient synchronization membrane potentials Local field potential In mushroom body: Measures average AL activity (cell in mushroom body)

  31. 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

  32. Model (Bazhenov et al) • 90 PNs, 30 LNs

  33. Model (Bazhenov et al) • 90 PNs, 30 LNs • Single-compartment, conductance-based neurons

  34. Model (Bazhenov et al) • 90 PNs, 30 LNs • Single-compartment, conductance-based neurons • (post)synaptic kinetics

  35. Model (Bazhenov et al) • 90 PNs, 30 LNs • Single-compartment, conductance-based neurons • (post)synaptic kinetics • Fast excitation, fast and slow inhibition

  36. 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

  37. 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

  38. Bazhenov network

  39. Excitatory neurons

  40. Excitatory neurons Active currents:

  41. Excitatory neurons Active currents: Na

  42. Excitatory neurons Active currents: Na K

  43. Excitatory neurons Active currents: Na K A-current

  44. Excitatory neurons Active currents: Na K A-current Synaptic input

  45. Excitatory neurons Active currents: Na K A-current Synaptic input Fast (ionotropic) synaptic currents (nACh and GABAA): ( [O] is open fraction)

  46. 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:

  47. 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:

  48. Slow inhibition Kinetics like GABAB

  49. Slow inhibition Kinetics like GABAB G-protein concentration:

  50. Slow inhibition Kinetics like GABAB G-protein concentration: Activated receptor concentration

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