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Monosynaptic reflex

Monosynaptic reflex. Amy MacDermott, Department of Physiology and Cellular Biophysics and the Center for Neurobiology and Behavior phone 305-3889 email abm1@columbia.edu. Physiology G6001 Nerve and Synapse.

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Monosynaptic reflex

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  1. Monosynaptic reflex

  2. Amy MacDermott, Department of Physiology and Cellular Biophysics and the Center for Neurobiology and Behavior phone 305-3889 email abm1@columbia.edu Physiology G6001 Nerve and Synapse Classical elements of synaptic transmission: Neuromuscular junction Transmitter release Synaptic currents Synaptic potentials Nerve-nerve synapses Synaptic integration Summation Facilitation

  3. Schematic of the NMJ

  4. The Neuromuscular Junction

  5. Physiology G6001 Nerve and Synapse Classical elements of synaptic transmission: Neuromuscular junction Transmitter release Synaptic currents Synaptic potentials Nerve-nerve synapses Synaptic integration Summation Facilitation

  6. Exocytosis and transmitter release at the nerve terminal

  7. Protein machinery for vesicle release Rizo and Sudhof Nature Reviews Neuroscience3; 641-653 (2002);

  8. Key elements of transmitter release

  9. Recording from the neuromuscular junction (NMJ).Spontaneous release of a vesicle of Ach causes a miniature endplate potential or MEPPEvoked release following stimulation of the motor neuron causes an endplate potential or EPP

  10. Presynaptic calcium channels at the neuromuscular junction (NMJ)

  11. Pre and postsynaptic changes in membrane potential during transmitter release

  12. Recording from the neuromuscular junction (NMJ).Spontaneous release of a vesicle of Ach causes a miniature endplate potential or MEPPEvoked release following stimulation of the motor neuron causes an endplate potential or EPP

  13. The quantal nature of transmitter release.Decrease the amplitude of evoked release by recording in low Ca2+ bath.

  14. Physiology G6001 Nerve and Synapse Classical elements of synaptic transmission: Neuromuscular junction Transmitter release Synaptic currents Synaptic potentials Nerve-nerve synapses Synaptic integration Summation Facilitation

  15. NMJ – an inward current drives the change in membrane potential

  16. Membrane potential and driving force– brief reviewVm= (RT/F) ln [K]o/[K]i Vm= (RT/F) ln Na]o/[Na]i

  17. Reversal potential____________IEPSP = gEPSP x (Vm-EEPSP)

  18. Membrane time constant – a review

  19. Synaptic potential is not actively propagated

  20. ACh binds to the nicotinic ACh receptor, causing it to gate open. The channel is permeable to both Na+ and K+.The end-plate potential causes voltage gated Na+ channels to open and an action potential to fire.

  21. An EPP in normal muscle is super-threshold for firing action potential

  22. Physiology G6001 Nerve and Synapse Classical elements of synaptic transmission: Neuromuscular junction Transmitter release Synaptic currents Synaptic potentials Nerve-nerve synapses Synaptic integration Summation Facilitation

  23. Heuser and Reese – two synapses in the cerebellum

  24. a b - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + g + + + + + + + + + + + + + + + + + Classes of neurotransmitter receptors - OUT + + + + - - - - - - - - - - - - IN IONOTROPIC METABOTROPIC

  25. GLU GLU, KA GLU, NMDA b g Excitatory synaptic transmission is mediate by glutamate receptors (Ca2+?) Na+, Ca2+ Na+, GLU, KA OUT a IN * K+ K+ metabotropic Glu receptors NMDA receptors (NMDARs) AMPA receptors Kainate receptors

  26. Current-voltage relationship for synaptic currents mediated by AMPA and NMDA receptors

  27. Inhibitory synaptic transmission is mediated by GABA and glycine receptors

  28. Physiology G6001 Nerve and Synapse Classical elements of synaptic transmission: Neuromuscular junction Transmitter release Synaptic currents Synaptic potentials Nerve-nerve synapses Synaptic integration Summation Facilitation

  29. Membrane time constant – a review

  30. What determines the time course of the synaptic potential?

  31. Temporal summation depends on the passive membrane properties of the neuron or muscle Tau or t = C x R

  32. Summation is postsynaptic while facilitation is usually presynaptic

  33. Summation of EPSP and IPSP

  34. The trigger zone

  35. The synaptic potential is not actively propagated. The rate of decay with distance is exponential: DV(x) = DV0 e-x/l and l ~ (rm/ra)

  36. Different synaptic configurations including axo-somatic, axodendritic and axo-axonic

  37. Implications of synapse location Length constant l ~ Rm/Ra

  38. Temporal and spatial summation: importance of time constant t and length constant l

  39. Three forms of modulation of synaptic transmission mediated by metabotropic receptors

  40. Berne and Levy – chapter 4orKandel, Schwartz, and Jessell – chapters 11 and 12or Kandel, Schwartz, and Jessell – chapters 10-15

  41. Recording from the neuromuscular junction (NMJ).Spontaneous release of a vesicle of Ach causes a miniature endplate potential or MEPPEvoked release following stimulation of the motor neuron causes an endplate potential or EPP

  42. The reversal potential is determined by the concentrations of ions flowing through the synaptic channel.

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