1 / 40

PART 4: BEHAVIORAL PLASTICITY #20: LEARNING & MEMORY of a SIMPLE REFLEX in APLYSIA I

PART 4: BEHAVIORAL PLASTICITY #20: LEARNING & MEMORY of a SIMPLE REFLEX in APLYSIA I. model system: sea hare ( Aplysia californica ) behavior: the gill & siphon withdrawal reflex cell biology: learning & memory summary. PART 4: BEHAVIORAL PLASTICITY

norman-bowman
Télécharger la présentation

PART 4: BEHAVIORAL PLASTICITY #20: LEARNING & MEMORY of a SIMPLE REFLEX in APLYSIA I

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PART 4: BEHAVIORAL PLASTICITY #20: LEARNING & MEMORY of a SIMPLE REFLEX in APLYSIA I • model system: sea hare (Aplysia californica) • behavior: the gill & siphon withdrawal reflex • cell biology: learning & memory • summary

  2. PART 4: BEHAVIORAL PLASTICITY #20: LEARNING & MEMORY of a SIMPLE REFLEX in APLYSIA I • model system: sea hare (Aplysia californica) • behavior: the gill & siphon withdrawal reflex • cell biology: learning & memory • summary

  3. SEA HARE ( Aplysia californica) • slow moving gastropod mollusk • phylum: Mollusca • order: tectibranchia • subclass: Opisthobranchia • genus: Aplysia, about 35 species • A. californica: 15-30 cm, south Pacific waters • few (~ 20K) neurons, some very large & identifiable •  can associate neural function with behavior • circuitry, cell & molecular biology of learning

  4. SEA HARE ( Aplysia californica) • gill & siphon withdrawal reflex • top view of A. californica • tactile stimuli  gill & siphon withdrawn under mantle & covered with parapodium • reliable behavior • > 30 yrs of study • neural mechanisms of learning

  5. THE GILL & SIPHON WITHDRAWL REFLEX • we will focus on 2 main ideas in this chapter • non-associative vs associative learning • memory phases

  6. THE GILL & SIPHON WITHDRAWL REFLEX • in very general terms, what can animals learn? • a single stimulus • temporal relationships among stimuli • influence of own behavior on #2 • different types of learning: • non-associative learning  #1 only • associative learning • Pavlovian or classical  #1 & 2 • operant or instrumental  #1, 2 & 3

  7. THE GILL & SIPHON WITHDRAWL REFLEX • study using Aplysia restrained in aquarium • tactile stimulation to siphon  gill retraction • repeat at 90s interval  habituation • electric shock stimulation to tail (or neck) • gill retraction restored  dishabituation

  8. THE GILL & SIPHON WITHDRAWL REFLEX • study using Aplysia restrained in aquarium • tactile stimulation to siphon  gill retraction • repeat at 90s interval  habituation • electric shock stimulation to tail (or neck) • gill retraction restored  dishabituation • electric shock stimulation to tail in naive animals • gill retraction enhanced  sensitization • memory fairly short for all three types (min or hrs) • long-term forms can also be generated

  9. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: classical or Pavlovian • US = tail shock • UR = rigorous siphon withdrawal • CS = siphon stimulus

  10. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: classical or Pavlovian • US = tail shock • UR = rigorous siphon withdrawal • CS = siphon stimulus • training: US + CS • test: CR = rigorous siphon withdrawal

  11. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: classical or Pavlovian • test with CS alone after training with: • US only  sensitization control • US + CS unpaired = stimulus control • US + CS paired = classical conditioned • learn siphon stimulus predicts tail shock

  12. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: differential classical • US = tail shock • UR = rigorous siphon withdrawal • CS1+ = siphon (or mantle stimulation) paired • CS2– = mantle (or siphon stimulation) unpaired

  13. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: differential classical • US = tail shock • UR = rigorous siphon withdrawal • CS1+ = siphon (or mantle stimulation) paired • CS2– = mantle (or siphon stimulation) unpaired • training: US + CS1+ paired, US + CS2– unpaired • test: CR = rigorous siphon withdrawal

  14. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: differential classical • test with CS1 or CS2 alone after training with: • CS1+ = siphon (or mantle stimulation) paired • CS2– = mantle (or siphon stim.) unpaired • learn that CS+ predicts tail shock

  15. THE GILL & SIPHON WITHDRAWL REFLEX • associative learning: interstimulus interval • CS must precede US in training • 0.5 s in A. californica • no learning with backward conditioning

  16. THE GILL & SIPHON WITHDRAWL REFLEX • long-term memory • short-term memory:  minutes / hours • long-term memory:  days / weeks • distributed (spaced) vs massed training is the key SPACED MEMORY MASSED TIME

  17. THE GILL & SIPHON WITHDRAWL REFLEX • long-term memory in habituation • train: 4 days (T1-4) • test: 1 day (R1), 1 wk (R2), 3 wks (R3)

  18. THE GILL & SIPHON WITHDRAWL REFLEX • long-term memory in habituation • train: 4 days (T1-4) • test: 1 day (R1), 1 wk (R2), 3 wks (R3)

  19. THE GILL & SIPHON WITHDRAWL REFLEX • long-term memory in sensitization • train: 4 days (T1-4) • test: 1 day (R1), 1 wk (R2), 3 wks (R3)

  20. THE GILL & SIPHON WITHDRAWL REFLEX • long-term memory in associative learning • data not shown

  21. CELL BIOLOGY OF LEARNING & MEMORY • functional architecture of withdrawal reflexes • ganglia & connectives • bilaterally symmetrical prs • abdominal ganglion important for reflex: • 1° sensory neurons • interneurons • motor neurons

  22. CELL BIOLOGY OF LEARNING & MEMORY • functional architecture of withdrawal reflexes • neural circuit of reflex • ~ 20 sensory neurons  motor neurons • interneurons • excite • inhibit

  23. CELL BIOLOGY OF LEARNING & MEMORY • functional architecture of withdrawal reflexes • neural circuit of reflex • ~ 20 sensory neurons  motor neurons • interneurons • excite • inhibit • focus on synapses

  24. CELL BIOLOGY OF LEARNING & MEMORY • big +s for using Aplysia: • direct monitor of synaptic transmission... • of identified neurons... • in numerous different preparations... • to measure behavior

  25. CELL BIOLOGY OF LEARNING & MEMORY • intact preparation • expose abdominal ganglion • gill & siphon withdrawal triggered & measured • simultaneous intracellular recordings

  26. CELL BIOLOGY OF LEARNING & MEMORY • semi-intact preparation • separate organs with neurons • reliable recording

  27. CELL BIOLOGY OF LEARNING & MEMORY • isolated abdominal gangion • direct access to all neural elements • mimic tactile stimulation with neural stimulation

  28. CELL BIOLOGY OF LEARNING & MEMORY • cell culture • most reduced • examine properties of single synapses between sensory and motor neurons • reconstruct monosynaptic component of reflex

  29. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – the synapse • synaptic facilitation • semi-intact preparation • electrically stimulate tail •  sensory to motor EPSP • presynaptic mechanism •  Ca++ into neuron •  transmitter release • spike broadening

  30. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – the synapse • synaptic facilitation • semi-intact preparation • serotonin application •  sensory to motor EPSP • serotonin blocker • prevents  sensory to motor EPSP (not shown)

  31. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – biophysics • serotonin  sensory to motor EPSP • whole cell current: voltage clamp • single ion channel patch clamp • serotonin  outward K-current by... • prolonged closure of 2 S-current channels: • “serotonin-sensitive K current” (S current) • delayed K current • prevents repolarization of membrane • leads to spike broadening

  32. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – molecular

  33. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – molecular • synaptic facilitation • semi-intact preparation • inject cAMP 2nd messenger •  sensory to motor EPSP

  34. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of sensitization – molecular • inject PKA catalytic subunit same result • phosphorylates (closes) K-channels • sensitization model incomplete…

  35. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of classical conditioning • presynaptic factors • similarities with sensitization • reflex facilitation of siphon withdrawal • induced by tail shock • facilitation amplified by temporal CS-US pairing • same (amplified) mechanism or not?

  36. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of classical conditioning • presynaptic factors • similarities with sensitization • reflex facilitation of siphon withdrawal • induced by tail shock • facilitation amplified by temporal CS-US pairing • same (amplified) mechanism or not? • test with differential conditioning paradigm

  37. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of classical conditioning • presynaptic factors • semi-intact preparation • CS1 = siphon (SN) • CS2 = mantle (SN) • US = tail shock

  38. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of classical conditioning • presynaptic factors • enhanced facilitation in paired training •  = paired vs unpaired •  = paired vs US alone • temporal pairing effect • activity-dependent presynaptic facilitation

  39. CELL BIOLOGY OF LEARNING & MEMORY • mechanistic analysis of classical conditioning • presynaptic factors • differential synaptic facilitation results similar to behavioral experiments

  40. BREAK

More Related