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Cell communication III: the nerve system

Cell communication III: the nerve system. 3-28-2016. Nature 510: 38; 2014. Resting membrane potential is maintained by Na-K ATPase and ATP hydrolysis. Two characteristics of action potential of neuron. All or none; Unidirectional!.

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Cell communication III: the nerve system

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  1. Cell communication III: the nerve system 3-28-2016

  2. Nature 510: 38; 2014.

  3. Resting membrane potential is maintained by Na-K ATPase and ATP hydrolysis

  4. Two characteristics of action potential of neuron All or none; Unidirectional!

  5. The refractory period after opening of voltage gated ion channel makes unidirectional propagation of action potential

  6. Conduction of the Action Potential • All-or-None Law • the principle that once an action potential is triggered in an axon, it is propagated, without decrement, to the end of the fiber • Rate Law • the principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires

  7. Schwann cell is responsible for myelination of peripheral neuron Why different cell type for myelination in CNS and PNS?

  8. Transmission of this message, hopping from node to node, is called saltatory conduction, from the Latin saltare,“to dance.” • Saltatory Conduction • Conduction of action potentials by myelinated axons: the action potential appears to jump from one node of Ranvier to the next.

  9. Most of neurotransmitter receptor are ligand gated ion channel

  10.  EPSP: excitatory postsynaptic potential 

  11. How to terminate the postsynaptic signaling? • The neurotransmitter is degraded by the enzyme in postsynaptic terminal. • Acetylcholinesterase inhibitors in Alzheimer’s disease • The neurotransmitter is dissociated from the receptor and reuptake by presynaptic transporter. • Prozac is the blocker of presynaptic serotonin transporter

  12. The cortex has ~109 neurons. Each Neuron has up to 104 synapses

  13. Spine

  14. Central Hypothesis of learning – Synaptic plasticity • Synaptic plasticity • Changes in synaptic structure and biochemistry • Long-term potentiation (LTP) • Change in the strength of synaptic connections • Results from repeated activation

  15. Aplysia • 20,000 neurons in the CNS • The gill-withdrawal reflex, can be modified by • five different forms of learning: • habituation, • dishabituation, • sensitization, • classical conditioning, • operant conditioning.

  16. Why?

  17. Sensitization Pathway Release more serotonin at presynaptic terminal

  18. Long-term sensitization of the gill-withdrawal reflex of Aplysia leads to two major changes in the sensory neurons of the reflex (learning and memory) Persistent activation of protein kinase A Structural changes in the form of the growth of new synaptic connections.

  19. Long-term memory in Aplysia modulates the total number of varicosities of single identified sensory neurons PNAS85, pp. 2373-2377, 1988

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