Auditory transduction Figure by MIT OCW After figure

Auditory transduction Figure by MIT OCW. After figure 11. 13 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Hair cell receptor potentials l Hair cell diameter 500 nm l Subnanometer displacements can be detected Figure by MIT OCW. After figure 11. 14 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Cross-linked K+ channels • Opening of potassium channels causes depolarization (anomalous) • Voltage gated calcium channels cause release of neurotransmitter. Images removed due to copyright reasons. Please see figure 11. 15 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Inner hair cells dominate cochlear output Figure by MIT OCW. After figure 11. 16 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Amplification by outer hair cells • Mechanical amplification • Modulated by cholinergic efferents to the cochlea from the brainstem • Otoacoustic emissions and tinnitus. Images removed due to copyright reasons. Please see figure 11. 17 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Auditory pathways Images removed due to copyright reasons. • All ascending auditory pathways converge on the inferior colliculus.

Stimulus intensity Figure by MIT OCW. After figure 11. 20 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Tonotopic maps Images removed due to copyright reasons. Please see figure 11. 21 in Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Phase locking Figure by MIT OCW. After figure 11. 22 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Summary: frequency encoding • Low frequencies – Phase locking • Intermediate frequencies – Phase locking – Tonotopy • High frequencies – tonotopy

Cochlear implants • External microphone and speech signal processor • Radio link to implant • Stimulating electrodes in cochlea. • Bypass hair cells to restore hearing.

Prey capture by the barn owl Image removed. Please see http: //biology. caltech. edu/Members/Konishi

Interaural time delay l Not useful when the wavelength of sound is smaller than the ears (high frequencies) Images removed due to copyright reasons. Please see figure 11. 23 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Interaural intensity difference • The head casts a sound shadow • Not true at low frequencies due to diffraction. Images removed due to copyright reasons. Please see figure 11. 24 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Summary : sound localization • In the horizontal plane • Duplex theoty – 20 -2, 000 Hz • Interaural time delay – 2, 000 -20, 000 Hz • Interaural intensity difference

Encoding of time delay • Superior olive has binaural neurons • Inputs from left and right ventral cochlear nuclei • Selective for interaural time delay Figure by MIT OCW. After figure 11. 25 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Axonal delay lines • Coincidence detection • Phase locking is necessary, so only low frequencies are relevant Please see figure 11. 26 in: Images removed due to copyright reasons. Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Encoding of intensity Figure by MIT OCW. After figure 11. 27 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Vertical localization • Impairment if the pinna is bypassed with a tube in the auditory canal • Reflections off the pinna are important Figure by MIT OCW. After figure 11. 28 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Primary auditory cortex Figure by MIT OCW. After figure 11. 29 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Figure by MIT OCW. After figure 11. 30 in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.

Vestibular labyrinth Measuring angular velocity Anatomy of the VOR Images removed due to copyright reasons. Please see figures 11. 31, 11. 34, and 11. 37 respectively in: Bear, Mark F. , Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2 nd ed. Baltimore, Md. : Lippincott Williams & Wilkins, 2001. ISBN: 0683305964.