Sensory Physiology 309Susan was experiencing tinnitus (a ringing in the ears)
and rotational vertigo (feeling that the room was spin-
ning), and the specialist attributed these symptoms to
her having otosclerosis. In this condition, bone overgrows
the footplate of the stapes and the oval window. The sta-
pes is thereby immobilized, so that Susan has conduc-
tive deafness. A hearing aid would help this by allowing
the transmission of sound waves through bone to the
inner ear. However, surgical intervention, likely involving
the replacement of the stapes with a prosthesis, would
help. Susan also has myopia and needs stronger glasses
with a more concave lens. Alternatively, she could get her
cornea reshaped by LASIK surgery.
See the additional chapter 10 Clinical Investigations on
Meniere’s Disease and Transient Monocular Blindess in the
Connect site for this text| CHECKPOINT Clinical Investigation SUMMARY
18a. Describe the way in which ganglion cells typically
respond to light on the retina. Why may a small spot
of light be a more effective stimulus than general
illumination of the retina?
18b. How can the arrangement of the receptive fields of
ganglion cells enhance visual acuity?
18c. Describe the stimulus requirements of simple cortical
neurons.