Anatomy

1. What are the major subdivisions of the human brain? What are the general functions of each of these areas and the structures they contain?

2. What is the difference between the somatic and autonomic nervous systems? What are each of them used for? For the autonomic nervous system, what are the two major subdividisions, and how do they interact. Where are autonomic ganglia located?

3. Can there be afferent tracts in the CNS?

4. How do tracts, nerves, and commissures, and connectives differ?

6. Where is the main site of synaptic integration in the spinal cord, in invertebrate ganglia?

7. Large parts of the telencephalon can be removed and a person can still live. However, destruction of parts of the rhombencephalon or mesencephalon cause severe impairments or death. Why might that be so?

8. What is difference between the autonomic motor system and somatic motor system in terms of what each controls and how they control it ?
 

Sensory Systems

9. What makes a sensory neuron a sensory neuron?  Explain how they differ from motor neurons by describing differences in the kinds, and distribution of channels.

*10. Explain why mechanoreceptors are responsive to mechanical stimuli and not to light, and why photoreceptors are responsive to light and not mechanical stimuli.

*11. Define sensory transduction and give two examples.

*12. Compare the receptor potential to a synaptic potential.

*13. Explain labeled-line coding and give an example of what information is encoded by this method.

*14. Explain overrepresentation and give two examples.

*15. Give an example of parallel processing in one sensory modality in the CNS that allows for simultaneous feature extraction of at least 2 features of one stimulus.

16. What is reafference and how is it related to efferent innervation of sensory structures?  How could reafference be employed to generate rhythmic motor patterns/behavior?

*17. Describe a specific example of sensory reception.  Include a description of the physiological mechanisms and anatomy of filtering, transduction, amplification, coding of quality & coding of quantity, and transmission.

18. Describe 2 potential mechanisms for sensory adaptation.

19. What is the difference between convergence and divergence? What are the advantages of each? Can they occur in the same neural network? How?

20. Explain the concept of the "threshold tuning curve" and how it relates to receptor sensitivity. Note that a tuning curve consists of plotting amplitude of stimulus at threshold versus stimulus quality (e.g. sound frequency, temperature, electric voltage, light wavelength).

21. Explain what a receptor potential is. How does this differ from the resting membrane receptor potential?

22. How can you get transduction of the external environment from a stimuli without a depolarization event occuring? What system uses this type of mechanism?

23. How and why and where do environmental signals get amplified?

24. What types of receptor proteins are found in different modality receptor cells?

25. How does a primary sensory neuron differ from a secondary sensory neuron?

26. How does filtering SIMPLIFY the sensory input to a sensory receptor cell ?

27. When would you expect neurons in the CNS that receive inputs from sensory cells to use temporal or spatial summation and why ?

*28. What is meant by the "receptive field" of a sensory neuron? How could stimulus properties such as frequency and intensity be encoded by sensory neurons and differentiated by sensory systems?

29. What is the difference between population coding and spike pattern coding for encoding stimulus quality ? In a synchronized network of neurons would you expect to see spike pattern encoding or population encoding used ?

30. What is reafference and how does this come into play while attenuating to a specific stimulus?

31. What determines the modality of a receptor cell?  What determines the sensitivity of a receptor cell?

32. Define transduction and compare it to neurotransmission.  Which evolved first?  How could the second have evolved from the first?

*33. Define "receptive field" and explain how it relates to topographic organization.

*34. Describe the difference between labeled-line and population/across-fiber coding for stimulus quality. Receptors involved in which method are likely to be more narrowly-tuned?
 

Somatosensation

35. Explain why touch receptors located deep in the skin are not good at fine touch discrimination.  In other words, why are fine touch receptors located shallow in the skin?

36. Explain how adaptation is related to vibration sensation.

*37. Explain why dissociated sensory loss occurs when the spinal cord is hemisected.

38. Since modality of sensation is encoded by labeled lines, and the somatosensory cortex is somatotopically organized, explain what you would find if you were recording from the somatosensory cortex and stimulating the skin with stimuli of different modalities.

39. Outline where 2nd order and 3rd order neurons of the different sensory tracts reside.

40. Why would one benefit from having mechanoreceptors with a high threshold?  Isn't having a low threshold always desirable?

*41. Differentiate between fast and slow pain.  How does it propagate and what is its function?

42. Describe 4 types of receptors that are affected by temperature.

43. What might be the advantage of coupling a mechanoreceptor to an ion channel as opposed to modifying a signal transduction cascade. What about the reverse situation, the advantage of a mechanoreceptor using a signal transduction cascade.
 

Electric and Magnetic

44. How does the electrosensory system of electrogenic fish differ from that of non-electrogenic fish?  Why?

45. Explain the purpose of the jamming avoidance response.

*46. Describe three mechanisms for magentic transduction.
 

Vision

47. An exercise fanatic overdoes it at the gym one night after forgetting to eat all day. He shocks his fellow fitness freaks when he faints in the middle of the weight room. Moments before he goes unconscious he is completely unable to see. Why is his vision so acutely affected by his physiological condition? Why do we "black out" right before we faint?

48. Why could the eyes be called accessory structures? How does the anatomy of the eye aid the photoreceptors?

49. Describe how temporal summation and delay lines can be employed to detect motion of a stimulus in space? (e.g. moving visual stimuli or moving touch stimuli).  A drawing might be useful.

50. Which LGN receives visual information from the left eye?

51. The cells making up the visual cortex are said to follow an hierarchical organization. What are the types of cells making up this hierarchy and what are their functions?

*52 Where in the brain does the parallel processing of visual input occur? Why does it make sense for parallel processing to occur at this locus in the visual relay? How do think selectively disabling the parvocellular layers of this processing region would affect an individual's vision?

*53. Photoreceptors must work in both bright light and dim light to allow us to see over a wide range of light levels. Based on what you learned in lecture about photorecptor signal transduction, what are some ways you can think of through which this change in sensitivity to light might be accomplished

54. What is a receptive field, and how does it differ between the cellular subtypes found in the retina. (ie, for photoreceptor cells, bipolar, ganglion cell)

*55. Map the projections of fibers (neural) from the retina to the thalamus to the cortex. (just the basics to understand anatomy of the system) Include the major cell types of the retina all the way to the final end point in the cortex).

*56. Describe the receptive field of an ON-center/OFF-surround ganglion cell in the retina.  Explain why this ganglion cell has such a receptive field (i.e. describe the responses & synaptic mechanisms employed by the cells presynaptic to this ganglion cell).  A diagram might be useful.  Explain how this differs from an OFF-center/ON-surround receptive field.

57. Suppose in the LGN you need a cell that detects the following field: +. Show how you would design a simple cell that detects this patern as well as a complex cell that could detect it. (Yes, I know that simple cells are tuned only to a bar of light, but imagine we theoretically could tune them to the pattern above).

58. Explain how you get center on surround off fields for bipolar cells.

59. Our eye has three different types of cones: red, green, blue. Explain how this fits in with the concept of range fractionation.

60. Explain what changes you might expect in a rod photoreceptor that would account for photobleaching. Why do we need photobleaching in the first place?

*61. Explain how lateral inhibition is used to enhance contrast for visual images.

62. Packing the rods with a lot of membrane bound photoreceptor proteins allows them to respond to low levels of light, but what disadvantage might this have under different conditions?

63. Draw the neural circuit of how rods communicate with the brain.  Show convergence and receptors, bipolar cells, horizontal cells, and ganglion cells.

64. Draw the neural circuit of how cones communicate with the brain.  Show receptors, bipolar cells, horizontal cells, and ganglion cells.  Note which synapses are excitatory and which are inhibitory.  Have you drawn and on-center system or off-center?  How could you change one to the other by changing one protein type?

*65. Describe the process of light transduction.

*66. Explain how convergence in a sensory system affects sensitivity and resolution of stimulus location.

67. Explain the difference between the synaptic input to a P and an M ganglion cell.  What is the functional consequence of this difference?

68. Describe parallel processing and relate this to labeled-line coding.

69. Draw a neural circuit of 3 ganglion cells, 3 LGN neurons, and 1 simple cortical cell showing why the receptive field of simple cortical cells is a bar of certain angle.

*70. Explain how higher order neurons exhibit emergent properties not present in the lower neurons that send input to them.

*71. What do secondary and higher cortical areas do for visual processing?
 

Audition

72. What is the difference between topographical mapping of sensory space (ie. retinotopic, tonotopic etc) and a "centrally synthesized" mapping? What kind of mapping is the auditory system believed to have?

73. Does the auditory system of the barn owl have serial or parallel type processing with regard to a response to a single stimuli (ie, the quality of the stimulus)?

74. What is meant by a coincident detector, and how does it relate to auditory processing?

75. Explain how spike timing might be used to encode interaural time differences.

*76. Follow the vibrations associated with sound from the air to the cochlea.  What do high frequency vibrations affect different receptors than low frequency vibrations?

77. Why does your voice sound louder to others than to you?

*78. What accessory structure is primarily involved in providing frequency selectivity in the auditory system?

*79. What is a place code?  What is being coded?  How is that code transmitted to the brain?

*80. How is sound transduced?  What cells do this?

*81. Differentiate between the role of the place code and the rate code in the auditory system.

82. Outer hair cells respond to sounds, but do not send afferents to the brain to report the presence of sound.  What is their role in hearing?

83. What is tonotopy, and what does it imply about labeled-lines in the auditory pathways?

84. What is a function of higher order auditory cortex?

*85. How is a sound source localized in the horizontal plane?  How and why does the method vary for different frequencies?

86. What is the role of the medial, and the lateral superior olivary nuclei in localizing sound sources?

87. How is sound localized in the vertical plane?  What are spectral differences?

88. How does one resolve the ambiguity between a sound coming from 45° behind you versus 45° in front of you?
 

Chemical

89. Why do hot peppers feel "hot" even when cold?

90. What is unique about the origin of olfactory receptors compared to other sensory neurons?

*91. Why do you suppose hearing primary afferents are myelinated and olfactory primary afferents are not?

*92. How are different smells transduced & coded in the olfactory system?

93. Explain how population coding can resolve the ambiguous affects of different tastants and different intensities (concentrations) on action potential rate.

94. How is salty, sweet, bitter and sour transduced?

*95. Why do olfactory receptors have cilia?

modified 10-10-01