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MEDS 371
Auditory system II:
hindbrain
Dr. Duck O. Kim
cat brain dissected showing auditory system
cerebellum
auditory
cortex
inferior
colliculus
medial
geniculate
cochlear
nucleus
Oliver
auditory nerve
h
tonotopic
organization
of CN
cat CN
dorsal
DCN
anterior
h
AVCN
CN: cochlear nucleus
DCN: dorsal CN
PVCN
AVCN: anterovent. CN
h
PVCN: posterovent. CN
Arnesen & Osen, 1978
type I (95%)
1. spherical bushy cell; AVCN
2. stellate cell; VCN
3. globular bushy cell; AVCN
4. octopus cell; PVCN
5. fusiform cell; DCN
Kiang, 1975
cells in the cochlear nucleus
PST histogram
F
O
PST histogram
GB
spiral ganglion
neuron
type I (95%)
S
SB
Kiang, 1975
end bulbs of Held at bushy cells of the AVCN
Ryugo, 1999, Fig-10
intrinsic properties
EPSPs
cochlear nucleus
neurons
intracellular recording
in brain-slice
preparation
Oertel et al., 1988
The "where-processing" of sound:
Neural representation of auditory space
requires de novo computation
unlike the retinotopic map.
Kim, Bishop, Kuwada, 2010
head-related impulse responses & transfer functions of rabbit
Sound localization cues
* interaural time difference (ITD)
5 μsec; ~ 1 deg azimuth.
* interaural level difference (ILD)
* spectral cues
* direct/reverberant energy ratio; distance
virtual auditory space
cortex
the ascending
auditory pathways
of the cat
thalamus
midbrain
binaural &
monaural
pathways
CN & SOC
pons
Brodal, 1981
Brodal Fig 9-8
mso: medial sup. olive; lso: lateral sup. olive
ntb: nuc. trazepoid body; ic: inf. coll.
cat superior olivary complex
LSO
LSO
MSO
MSO
MNTB
MNTB
D
M
(somata & dendrites)
(axons & endings)
Tsuchitani, 1978, Fig. 10
ILD processing in LSO
Purves Fig 13-14A
Purves Fig 13-14B
ILD processing in LSO
model for ITD coding employing
neural delay lines & coincidence detectors
MSO neurons act as
coincidence detectors.
maximum firing when
left (acoustic delay + neural delay) =
right (acoustic delay + neural delay)
Jeffress, 1948; Kuwada
best ITD 1 = 0 ms; sound in front
best ITD 2 = 50 ms
best ITD 3 = 100 ms
...
best ITD 7 = 700 ms;
sound on opposite side
Kim, Bishop, Kuwada, 2010
head-related impulse responses & transfer functions of rabbit
Inferior colliculus neurons show azimuth tuning.
10 dB
30 dB
50 dB
Kuwada, Bishop, Alex, Condit, Kim, 2011, J. Neurophys.
auditory &
somatosen.
inputs
Purves Box 20B
Sup. coll. contains visual and auditory space maps.
cortex
the descending
auditory pathways
of the cat
thalamus
midbrain
CN & SOC
pons
Brodal, 1981
olivocochlear neurons
LOC:
lateral
olivocochlear
MOC:
medial
olivocochlear
Warr et al., 2002
inner hair cell
outer hair cell
afferent
afferent
nerve
ending
afferent
afferent
nerve
ending
*
*
efferent
nerve
ending
efferent
nerve
fibers
Smith, 1975
afferent
nerve
fibers