01 nerve singnal processing


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01 nerve singnal processing

  1. 1. Objectives 1. Introduction and organization of Nervous system 2. Nerve signal processing 3. Sensory processing : Physical, chemical, EM 4. Motor control mechanism voluntary and involuntary 5. Consciousness, sleep, emotion reproduction 6. Cognitive function: Language, Memory… 7. Development of NS and Genetics 8. Cognitive Neurophilosophy 9. Recent development
  2. 2. Nerve Cell
  3. 3. Ion distribution across cell membrane A. Effect of concentration difference B. Electrical potential difference affecting negative ions C. Pressure difference
  4. 4. Ion movement across cell
  5. 5. Giant Nerve Cells of Squid
  6. 6. Resting membrane Potential
  7. 7. Patch-clamp setup A pipette containing acetylcholine (ACh) is used to record transmitter-gated channels in skeletal muscle. (Adapted from Alberts et al. 1989.)
  8. 8. Action Potential
  9. 9. Propagation of AP
  10. 10. Saltatory conduction
  11. 11. The Refractory Period
  12. 12. Synapse
  13. 13. Electrical synapse
  14. 14. Chemical Synapse
  15. 15. Neurotransmitter release
  16. 16. Post synaptic receptor
  17. 17. Depolarization & Repolarization of Post Synaptic Neuron
  18. 18. Excitatory and Inhibitory Post Synaptic Potential
  19. 19. Excitatory and inhibitory currents have competitive effects in a single nerve cell. (Adapted from Eckert et al., 1988.)
  20. 20. Second Messenger
  21. 21. Stretch Reflex
  22. 22. Inhibition
  23. 23. Reverberatory (Oscillatory) Circuit as a Cause of Signal Prolongation.
  24. 24. Neurotransmitters 1. The substance must be present within the presynaptic neuron 2. The substance must be released in response to presynaptic depolarization, and the release must be Ca2+-dependent. 3. Specific receptors for the substance must be present on the postsynaptic cell
  25. 25. Major classes of NT
  26. 26. Neruopeptide
  27. 27. Acetyl Choline
  28. 28. Cholinergic Receptors in Normal Brain
  29. 29. Alzheimer's disease
  30. 30. Serotonin System •originate in the median raphe of the brain stem •project to many brain and spinal cord areas, especially to the dorsal horns of the spinal cord and to the hypothalamus •acts as an inhibitor of pain pathways in the cord, and an inhibitor action in the higher regions of the nervous system •believed to help control the mood of the person, perhaps even to cause sleep.
  31. 31. Dopamine System •secreted by neurons that originate in the substantia nigra. •The termination of these neurons is mainly in the striatal region of the basal ganglia. •The effect of dopamine is usually inhibition •Parkinsonism is due to degeneration of substantia nigra with reduced dopamine •Schizophrenia there is increased dopamine
  32. 32. Norepinephric System •secreted by the terminals of many neurons whose cell bodies are located in the brain stem and hypothalamus •help control overall activity and mood of the mind, such as increasing the level of wakefulness •In most of these areas, norepinephrine probably activates excitatory receptors, but in a few areas, it activates inhibitory receptors instead •Norepinephrine is also secreted by most postganglionic neurons of the sympathetic nervous system, where it excites some organs but inhibits others
  33. 33. Glutamate System •the prominent glutamatergic pathways are: the cortico- cortical pathways; •the pathways between the thalamus and the cortex; and the extrapyramidal pathway o •other glutamate projections exist between the cortex, substantia nigra, subthalmic nucleus and pallidum. •Glutamate is an excitatory neurotransmitter
  34. 34. GABA System •Widespread in the brain and spinal cord •Inhibitory by increasing permeability to Cl
  35. 35. Nerve Conduction Study
  36. 36. Transcranial Magnetic Stimulation
  37. 37. SSEP
  38. 38. Auditory Evoked Response BAEP
  39. 39. VEP
  40. 40. Selected Reading