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Auditory System (SIGNAL TRANSDUCTION: HAIR CELLS (Releases …
Auditory System
SIGNAL TRANSDUCTION:
HAIR CELLS
Cilia tips are joined by
tip links
Cilia movement
produces tension in link,
which opens ion channel
in the adjacent tip
Ca2+
and
K+
flow in and
produce a
depolarization
As more stereocilia are deflected, the cell becomes
more depolarized but
DOES NOT FIRE AN ACTION POTENTIAL
Releases
neurotransmitter through
passive spread of charge
this is
Calcium
mediated
Voltage-gated channels still
open
Neurotransmitter activates Auditory Nerve
:explode:
EAR
Outer ear
Channel to
tympanic
membrane
(“Ear Drum”)
Middle ear
Ossicles
Inner ear :explode:
Cochlea
: fluid-filled
Auditory nerve
NEURAL CODE OF
FREQUENCY
Frequency of sounds
are coded by
responses of hair cells
Place Code
:red_flag:
Spot along basilar membrane that
moves the most
The auditory system is
tonotopic
PLACE CODE: THICKNESS OF
COCHLEAR BASILAR MEMBRANE
:explode:
Pathway of Auditory System
Place Theory/code
Frequency matching :explode:
SOUND LOCALIZATION
BARN OWL
Sound localization determine :explode:
Interaural Time Difference (ITD)
:
Temporal disparity between
signals reaching two ears
(onset time and phase)
Interaural Level Difference (ILD)
:
Differences in amount of
attenuation and amplification of
signals between ears
AUDITORY CORTEX IN PRIMATE
Multiple tonotopically organized maps
Core
Belt
Parabelt
AUDITORY CORTEX :explode:
Lesions in humans and primates:
To core region: Impairments in sound detection
To belt or parabelt region: Impairment in sound pattern perception
(e.g., discrimination of tone sequences)
