Questions presented here came from previous exams,
and may test material not presented in this year's lectures.


  1. The difference between sensation and perception is whether information about a stimulus reaches the central nervous system.  Answer

  2. The cochlea extracts frequency and intensity information from acoustic stimuli, but interactions among neurons in the central nervous system are necessary to localize sounds.  Answer

  3. Neurons faithfully carry information about each sensory modality along specific parallel pathways, with none of the information being altered by other regions of the central nervous system.  Answer

  4. Light results in the opening of sodium channels in the membrane of photoreceptor cells, resulting in a depolarization of the rod (or cone). Answer

  5. Taste receptors use several mechanisms, including direct ion channel activation and receptors coupled to second messenger systems, to detect the presence of different tastant molecules.  Answer

  6. Lateral inhibition is a mechanism whereby the nervous system narrows an area of sensation relative to the area of receptor activation.  Answer


  1. Information about stimulus intensity is coded by:   Answer

    1. increasing the number of fibers responding to the stimulus

    2. the amount of the receptive field of stimulated

    3. the magnitude of the receptor potential

    4. all of the above.

  2. Which of the following statements is FALSE:   Answer

    1. during transduction of auditory stimuli, ion channels located at the tips of the stereocilia are mechanically opened, resulting in depolarization of the inner hair cell

    2. the tonotopic representation of frequency is passed from the lateral geniculate nucleus to the primary auditory cortex

    3. the main function of the middle ear is to match the impedance of air to the impedance of the fluid in the cochlea

    4. basilar membrane vibration is frequency dependent:  high frequency sounds produce larger deflections in the base of the cochlea, and low frequency sounds in the apex.


9.        Explain the paradox inherent in the encoding of stimulus location and intensity, and provide a brief description of one mechanism used by the central nervous system to resolve this problem.  Answer

10.      Outline the steps in the transduction process that occurs in rod cells, and indicate how this process contributes to the sensitivity of the visual system.     Answer