Neuro Exam 1.10

  1. Coding
    initial algebraic temporal and spatial summation which is used to determine excitatory or inhibitory activities of 2nd order sensory neuron
  2. Where are 1st order sensory neurons found?
    in PNS
  3. The 1st order sensory neurons enter what to synapse w/ 2nd order?
    enter CNS
  4. Where does the 1st order sensory neuron synapse with the 2nd order?
    Spinal cord or brainstem
  5. What occurs at the 2nd order sensory neuron?
    • coding
    • -initial temporal and spatial algebraic summation must take place
    • -cell body decides whether or not to fire on 3rd
  6. Where are 2nd order sensory neurons found?
    throughout the NS
  7. What do 2nd order sensory neurons form?
    ascending sensory pathways (generally go to thalamus)
  8. Where are 3rd order sensory neurons found?
    in CNS
  9. Where do 3rd order sensory neurons end up?
    at cortex in post central gyrus
  10. What is the post central gyrus?
    primary sensory cortex, responsible for perceiving sensation
  11. What are the different types of synapses?
    • axosomatic
    • axodendritic
    • axoaxonic
    • dendrodendritic
  12. Are axosomatic synapses excitatory or inhibitory?
  13. Are axodendritic synapses excitatory or inhibitory?
  14. Are axoaxonic synapses excitatory or inhibitory?
  15. Are dendrodendritic synapses excitatory or inhibitory?
  16. What two ways is coding expressed?
    • rate
    • pattern
  17. What is rate of coding?
    • frequency--expressed in Hz
    • rate=impulse/sec
  18. What is pattern of coding?
    variation in rate
  19. With inhibitory synapses, rate is:
    interrupted and it varies the pattern
  20. Inhibition:
    brain's most fundamental capability
  21. Charles Sherrington described the brain's ability to choose b/w
    competing alternatives --to select one and suppress the others-- as the
    integrative action of the nervous system.
    Regarded this decision making as the brain's most fundamental capability
  22. Inhibition v. excitation:
    brain decides to be excited or not excited
  23. What would happen if inhibition did not work?
    • could not have any mm contraction
    • could not make sense out of special sensory input (visual or auditory), the brain would be blurry --also applies to emotions
  24. Is inhibition the same concept as not using all of your brain?
    no, it takes energy to inhibit neurons
  25. Dis-inhibition:
    mechanisms which prevent inhibition
  26. Dis-inhibition is important under certain conditions to:
    eliminate inhibition to increase activity of another function
  27. What are some examples of the value of dis-inhibition?
    • maximize movement
    • increase awareness of special sense
  28. What is the end result of dis-inhibition?
    increase activity
  29. What type of disease is an example of dis-inhibition?
    Parkinson's disease
  30. What is Parkinson's disease?
    • basal ganglia inhibits activity (has been dis-inhibited pathologically b/c of shortage of dopamine)
    • Causes involuntary tremors
  31. What are the mechanisms for inhibition?
    • negative feedback loop
    • presynaptic inhibition
    • feedback inhibition
    • feed-forward inhibition
    • descending supraspinal inhibitory mechanisms
  32. Where are negative feedback loops common?
    spinal cord
  33. What type of cells do negative feedback loops use?
    Renshaw cells
  34. What are Renshaw cells?
    • inhibitory neuron
    • interneurons
  35. Why do negative feedback loops use Renshaw cells?
    for a means by which the neuron can influence its own activity (dampens or decreases activity--shut itself down)
  36. Where are Renshaw cells located?
    b/w collateral branch of lower motor neuron and a dendrite and cell body region of same LMN and other LMNs
  37. The lower motor neuron releases ACh onto:
    Renshaw cell (an excitatory NT)
  38. Assuming an AP occurs, Renshaw cells release:
    glycine (major inhibiotry NT) at the synapse (axodendritic)
  39. What does the release of glycine by the Renshaw cells cause?
    resultant hyperpolarization, causing an inhibition (IPSP) on the NT
  40. What does the hyperpolarizaiton, causing an inhibition on the NT make?
    makes the cell fire less, therefore the skeletal muscle would contract less
  41. The negative feedback loops allow neuron to:
    keep itself under control (neuron self-regulation)
  42. What do presynaptic inhibitions involve?
    axoaxonic synapse
  43. Presynaptic Inhibition:
    • excitatory NT released from presynaptic axon to postsynaptic axon
    • graded potential occurs (due to EPSP lose vesicles; EPSP doesn't produce AP--graded)
    • AP does arrive, release NT but less than normal due to pre-release, therefore, less of an EPSP which has inhibitory effect; RMP lower amplitude due to prior depol
    • Since partially depoled, there is less Ca to enter postsynaptic membrane and flux inward
    • W/ less Ca, there is less NT released (tendency for it not to fire b/c not released enough NT(
    • axons excitatory but result of less NT, it is inhibitory
  44. Do all neurons have presynaptic inhibition?
    no, most do not
  45. Feedback Inhibition is also called:
    lateral or recurrent inhibition
  46. Feedback inhibition utilizes:
    inhibitory intra-neurons (Renshaw cells)
  47. In feedback inhibition, the most rapidly firing 2nd order sensory neuron depresses the activity of:
    • adjacent, less-active 2nd order sensory neurons
    • a contrast b/w active and less-active neurons is enhanced
    • results in enhancement of discrimintation of stimuli
  48. Feedback Inhibition alters signal to noise ratio as neurons become larger
    • 25Hz:20Hz is less than 25Hz:10Hz
    • 25:20 is not good, too much noise
  49. Feedback inhibition is particularly important where?
    inner ear
  50. Feed-forward inhibition is also called?
    reciprocal inhibition
  51. Feed-forward inhibition:
    one or more than one neuron inhibits another neuron or another group of neurons
  52. Where do feed-forward inhibitions occur?
    in brain or spinal cord
  53. In feed-forward inhibition, there are a limited number of:
    competing responses that are expressed while others are inhibited
  54. In a feed-forward inhibition, the extensors must shut down if it is wanting to use:
  55. Monosynaptic reflex:
    feed-forward inhibition
  56. What is an example of a monosynaptic reflex?
    • knee jerk
    • Renshaw cells send inhibitory message to knee flexors
    • LMN sends an excitatory message to knee extensors
  57. Descending supraspinal inhibitory mechanisms occur where?
    above the spinal cord, in the brain stem/brain and then descends to spinal cord
  58. What is another name for the descending supraspinal inhibitory mechanism?
    distal inhibition
  59. What does the descending supraspinal inhibitory mechanism involve?
    more than one relay neuron
  60. Descending supraspinal inhibitory mechanism:
    • naturally occurring pathway that deals w/ pain must be activated
    • activated via thought process that sends neurons to influence activity
    • activation releases inhibitory NT (endorphins) to reduce noxious (painful) stimulation
  61. What are examples of descending supraspinal inhibitory mechanism?
    • when you burn your hand in the kitchen, but you're not supposed to be there in the first place
    • you tell yourself it doesn't hurt as bad as it really does so that you don't yell and scream as much
  62. Does the descending supraspinal inhibitory mechanism wear off over time?
  63. Neural processing:
    mechanism by which CNS channels/focuses and sorts info
  64. Convergence:
    • many neurons synapse (converge) on a single neuron
    • --thousands of neurons can influence a single neuron (most input is indirect --but there is still influence)
  65. Convergence results in:
    focused input
  66. Convergence does what to information?
    focuses information
  67. Divergence:
    • means by which info from one neuron is spread to others
    • exponential
  68. Divergence does what to information?
    enhances spread of info
  69. Serial:
    • neurons are arranged sequentially
    • ascending (sensory) and descending (motor) pathways
  70. Parallel:
    • info is conveyed in parallel sequences
    • more than one pathway; two serial pathways that run parallel
    • involved w/ rehabilitation (damage one pathway, other pathways take up the slack--neuroplasticity)
Card Set
Neuro Exam 1.10
review of neuro lecture 10 for exam 1