Transcript Box 9.1 The Basics of Sound (Part 1)

Evolution of the Vestibular and
Auditory End Organs
External and Internal Structures of the Human Ear
External and Internal Structures of the Human Ear (Part 1)
External and Internal Structures of the Human Ear (Part 2)
External and Internal Structures of the Human Ear (Part 3)
External and Internal Structures of the Human Ear (Part 4)
External and Internal Structures of the Human Ear (Part 5)
Auditory Nerve Fibers and Synapses in the Organ of Corti
Dancing Outer Hair Cell - Video
How Stereocilia Sense Auditory Stimulation
Pitch Information Is Encoded in Two
Complementary Ways
The ability to detect a change in frequency is measured as the
minimal discriminable frequency difference between two
tones.
The detectable difference is about 2 Hz for sounds up to 2000
Hz; above these frequencies, larger differences are required.
Two theories of pitch discrimination:
Place coding theory—pitch is encoded in receptor location on
the basilar membrane.
Temporal coding theory—firing rate of auditory neurons
encodes the frequency of the auditory stimulus.
Basilar Membrane Movement for Sounds of
Different Frequencies
Auditory neurons have tonotopic organization.
Slow Motion GUITAR Strings Video
Examples of Tuning Curves of Auditory Neurons
Auditory Pathways of the Human Brain
Tonotopic Mapping in the Cat Inferior Colliculus
Tonotopic Organization of Auditory Cortical Regions in
Three Species of Mammals
Long-Term Retention of a Trained Shift in Tuning of
an Auditory Receptive Field
Congenital amusia (tone deafness)
• Impaired music perception affecting approximately 4% of
individuals
• A deficit in processing musical pitch but not musical time
• Genetically transmitted
• Compare families with amusic individuals to control families
• About one third of first-degree relatives In amusic families
share the impairment compared to only a few percent for the
control families
• Genes do not directly control cognitive functions such as music
perception
• Genes responsible for congenital amusia influence brain
development.
Figure 9.18 Structures of the Vestibular System
Nerve Fibers from the Vestibular Portion of the
Vestibulocochlear Nerve (VIII) Synapse in the Brainstem
• Nerve fibers from vestibular receptors synapse in
• the vestibular nuclei in the brainstem
• some fibers go directly to the cerebellum.
• The vestibulo-ocular reflex (VOR) allows you
to gaze at a fixed point while the head moves.
The Vestibulo-Ocular Reflex