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Neuronal Architecture of Behavior: From Cells to Circuits

Explore the intricate neural networks connecting behavior, synapses, and circuits. Learn about neuronal properties, synaptic transmission, and how nerve cells influence behavior. Discover the complexity and simplicity of neural pathways in different organisms.

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Neuronal Architecture of Behavior: From Cells to Circuits

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  1. #04: CELLS, SYNAPSES & CIRCUITS • behavior analysis • in a natural environment • in the laboratory • cells, synapses & circuits • basic properties of nerve cells • synaptic transmission • neuronal architecture & behavior • relating nerve cells to behavior • summary

  2. #04: CELLS, SYNAPSES & CIRCUITS • behavior analysis • in a natural environment • in the laboratory • cells, synapses & circuits • basic properties of nerve cells • synaptic transmission • neuronal architecture & behavior • relating nerve cells to behavior • summary

  3. #04: CELLS, SYNAPSES & CIRCUITS • behavior analysis • in a natural environment • in the laboratory • cells, synapses & circuits • basic properties of nerve cells • synaptic transmission • neuronal architecture & behavior • relating nerve cells to behavior • summary

  4. NEURONAL ARCHITECTURE OF BEHAVIOR • behavior  circuits of interacting neurons, 3 types: SENSORY INPUT CENTRAL PROCESSING MOTOR OUTPUT BEHAVIOR

  5. NEURONAL ARCHITECTURE OF BEHAVIOR • behavior  circuits of interacting neurons, 3 types: • sensory neurons... signal input • specialized receptor cells • convert features of environment neural signals • interneurons... central processing • motor neurons... motor output (behavior) • drive muscle activity @ neuromuscular junction • generate excitatory junctional potentials(EJPs)

  6. NEURONAL ARCHITECTURE OF BEHAVIOR • electrical recordings: • electrode type • position ~ cells • extracellular V,  • intracellular mV,  • advantages & disadvantages p.24, fig.1.10

  7. NEURONAL ARCHITECTURE OF BEHAVIOR • extracellular electrode • motor neurons • “unit” activity (>1) • ~ current flow in extracellular space p.24, fig.1.10

  8. NEURONAL ARCHITECTURE OF BEHAVIOR • intracellular electrode • single motor neuron p.24, fig.1.10

  9. NEURONAL ARCHITECTURE OF BEHAVIOR • extracellular electrode • records propagation of action potentials along axons p.24, fig.1.10

  10. NEURONAL ARCHITECTURE OF BEHAVIOR • intracellular electrode • muscle fiber • EJPs  signals... • motor neuron  • others p.24, fig.1.10

  11. NEURONAL ARCHITECTURE OF BEHAVIOR • extracellular electrode • electromyogram (EMG) • whole muscle activity p.24, fig.1.10

  12. NEURONAL ARCHITECTURE OF BEHAVIOR • behavior  circuits... simple ones (in mammals) • e.g., human knee jerk reflex... • tap knee below patella •  stretches receptors in quads (muscle spindles) • activates sensory neurons (Ia) • synapse  motor neurons () •  contraction of quads p.25, fig.1.11

  13. NEURONAL ARCHITECTURE OF BEHAVIOR • behavior  circuits... simple ones (in mammals) • e.g., human knee jerk reflex... • simple ? • sensory-motor ? • monosynaptic ? • no, other neurons involved p.25, fig.1.11

  14. NEURONAL ARCHITECTURE OF BEHAVIOR • circuit complexity • e.g., primate visual cortex • boxes = assemblies of • 103 s of neurons • 106 s of synapses • 2 main pathways • V1  PG... object location • V1  TE... visual form p.25, fig.1.11

  15. NEURONAL ARCHITECTURE OF BEHAVIOR • circuit complexity • e.g., primate visual cortex • Q: how to study cellular properties of neurons among such complexity ? • A: chose: • accessible behavior • in model organism providing special advantages p.25, fig.1.11

  16. NEURONAL ARCHITECTURE OF BEHAVIOR • advantages & disadvantages • interesting... it is ALL interesting (not only ~ humans) • maintenance, availability & access to sufficient #s • model system... biology & tools available • behavior • anatomy / physiology • cell biology • pharmacology • genetics / genomics / proteomics

  17. NEURONAL ARCHITECTURE OF BEHAVIOR • advantages & disadvantages • e.g., C. elegans (nematode) • cheap, maintenance, sample sizes, simple • behavior, simple anatomy, small simple & well- • characterized nervous system, development & cell • biology, genetic & pharmacological tools good • boring behavior, few properties of neuronal • assemblies or structures, small neurons • (electrophysiology difficult but accessible)

  18. NEURONAL ARCHITECTURE OF BEHAVIOR • advantages & disadvantages • e.g., H. sapiens (humans) • interesting behavior, need to knowing how we • function (medical), sequenced genome,  ~ easy • research funding arguments • prohibitively complex in every respect, moral • issues for invasive & experimental study, • expensive, inconvenient & uncooperative subjects

  19. #04: CELLS, SYNAPSES & CIRCUITS • behavior analysis • in a natural environment • in the laboratory • cells, synapses & circuits • basic properties of nerve cells • synaptic transmission • neuronal architecture & behavior • relating nerve cells to behavior • summary

  20. RELATING NERVE CELLS TO BEHAVIOR • investigating how neurons  behavior • e.g., crayfish response to tail tactile stimulus • record lateral giant interneuron (LGI) • correlation (A): always stimulusbehavior ?...  p.27, fig.1.12

  21. RELATING NERVE CELLS TO BEHAVIOR • investigating how neurons  behavior • e.g., crayfish response to tail tactile stimulus • record lateral giant interneuron (LGI) • correlation (A): always stimulusbehavior ?...  • sufficient (B): trigger LGI alone  response ?...  p.27, fig.1.12

  22. RELATING NERVE CELLS TO BEHAVIOR • investigating how neurons  behavior • e.g., crayfish response to tail tactile stimulus • record lateral giant interneuron (LGI) • correlation (A): always stimulusbehavior ?...  • sufficient (B): trigger LGI alone  response ?...  • necessary (C): shut off LGI  no response ?...  p.27, fig.1.12

  23. RELATING NERVE CELLS TO BEHAVIOR • investigating how neurons  behavior • e.g., crayfish response to tail tactile stimulus • record lateral giant interneuron (LGI) • correlation (A): always stimulusbehavior ?...  • sufficient (B): trigger LGI alone  response ?...  • necessary (C): shut off LGI  no response ?...  • should always attempt to ask these 3 questions, but • we rarely find this type of simplicity in nature

  24. RELATING NERVE CELLS TO BEHAVIOR • investigating how synapses  behavior • e.g., Drosophila escape response (mutants, pharmacological agents) • inject current across brain

  25. RELATING NERVE CELLS TO BEHAVIOR • investigating how synapses  behavior • e.g., Drosophila escape response (mutants, pharmacological agents) • inject current across brain • measure speed of transmission in down-stream motor neurons • chemical synapses: slow

  26. RELATING NERVE CELLS TO BEHAVIOR • investigating how synapses  behavior • e.g., Drosophila escape response (mutants, pharmacological agents) • inject current across brain • measure speed of transmission in down-stream motor neurons • chemical synapses: slow • electrical synapses: fast (middle leg) escape behavior

  27. RELATING NERVE CELLS TO BEHAVIOR • investigating how restricted neural networks  behavior • e.g., lobster ingestion • food  esophagus  3 chamber stomach: • cardiac sac • gastric mill • pylorus

  28. } rhythmic RELATING NERVE CELLS TO BEHAVIOR • investigating how restricted neural networks  behavior • e.g., lobster ingestion • food  esophagus  3 chamber stomach: • cardiac sac • pylorus (A) • gastric mill (C) p.28, fig.1.13

  29. RELATING NERVE CELLS TO BEHAVIOR • investigating how restricted neural networks  behavior • e.g., lobster ingestion • stomatogastric ganglia (STG)  rhythm • all 30 neurons known • circuits mapped (B,D) • functions in isolated preparations (A,C) p.28, fig.1.13

  30. RELATING NERVE CELLS TO BEHAVIOR • neural control  behavior in complex organism • e.g., selective attention in monkeys (stimulus choice) • unit recordings in cortex • cellular response to peripheral light (A) p.30, fig.1.14

  31. RELATING NERVE CELLS TO BEHAVIOR • neural control  behavior in complex organism • e.g., selective attention in monkeys (stimulus choice) • unit recordings in cortex • cellular response to peripheral light (A) • response > if animal pays attention (B) p.30, fig.1.14

  32. RELATING NERVE CELLS TO BEHAVIOR • neural control  behavior in complex organism • e.g., selective attention in monkeys (stimulus choice) • unit recordings in cortex • cellular response to peripheral light (A) • response > if animal pays attention (B) • response >> if animal  ~ behavior (C) p.30, fig.1.14

  33. RELATING NERVE CELLS TO BEHAVIOR • neural control  behavior in complex organism • e.g., selective attention in monkeys (stimulus choice) •  visual system response due to • ~ stimulus • other neural systems ~attention (& ~ activity ?) • gain some understanding of mechanism, even at this simple level of analysis

  34. #04: CELLS, SYNAPSES & CIRCUITS • behavior analysis • in a natural environment • in the laboratory • cells, synapses & circuits • basic properties of nerve cells • synaptic transmission • neuronal architecture & behavior • relating nerve cells to behavior • summary

  35. SUMMARY: INTRODUCTION & TERMS • behavior... examples discussed: • field studies  ethology • ethograms • FAP, SS, IRM, releasers, interlocking releasers • laboratory studies  associative learning • classical / Pavlovian conditioning, US, CS, UR, CR • operant/instrumental conditioning

  36. SUMMARY: INTRODUCTION & TERMS • nervous system • neurons • channels, resting potentials, action potentials • synapses • chemical, electrical, EPSPs, IPSPs • plasticity, synaptic depression & potentiation, presynaptic inhibition & facilitation • circuits • sensory neurons, interneurons, motor neurons • recording neural activity

  37. SUMMARY: INTRODUCTION & TERMS • relating nerve cells to behavior • neurons  behavior • crayfish tail flip response • synapses  behavior • Drosophila escape response • restricted circuits  behavior • lobster digestion • whole organism  behavior • monkey selective attention

  38. SUMMARY: WE HAVE NOT DISCUSSED… • nervous system development and plasticity… • neurogenesis, apoptosis and necrosis • growth • cell adhesion and axon pathfinding • formation, maintenance and plasticity of synapses • organogenesis • general brain and nervous system anatomy… • humans • other vertebrates • invertebrates

  39. SUMMARY: WE HAVE NOT DISCUSSED… • brains are not merely composed of neurons… glia… • oligodendrocytes* and astrocytes (CNS) • Schwann cells (PNS)* • form myelin sheath (vertebrates) • neuron cell structure… general categories… • microfilaments, neurofilaments and microtubules • axon transport • structure and functional details at synapses • ion channel anatomy

  40. SUMMARY: WE HAVE NOT DISCUSSED… • details about signals transmission… • action potentials • frequency coding • signal propagation • myelin function • “types” of signalling • silent, beating, bursting • effects of sustained neural stimulation • changing neuron properties

  41. SUMMARY: WE HAVE NOT DISCUSSED… • measuring currents and channels… electrophysiology… • criteria for ion channel activities • conductance, selectivity, gating, pharmacology • activation, inactivation • whole cell voltage clamp • patch (voltage) clamp • ion channel molecular biology and manipulation • maintenance of ion concentration gradients

  42. SUMMARY: WE HAVE NOT DISCUSSED… • intercellular communication… • gap junctions and neurosecretion • neurotransmitter release • transmitters and hormones • receptors and transduction mechanisms • neuromoduation

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