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SUPERIOR OLIVE
Douglas OliverUniversity of Connecticut Health Center
CORTEX
MGB
IC
DCN
VCN
SOC
COCHLEA
Auditory Cortex
Auditory Pathways
DLL
VLL
DLL
VLL
GLUTGABAGLY
InferiorColliculus
Medial Geniculate Body
IC
Auditory Pathways
Organization of Superior Olivary Complex
Subdivisions and Cytoarchitecture Neuron types Inputs Outputs Synapses Basic Circuit
Tsuchitani, 1978, Fig. 10
MSO
LSO
MNTB
MSO
LSO
MNTB
(somata & dendrites) (axons & endings)
D
M
Cytoarchitecture of Superior Olivary Complex
Comparative anatomy of SOC
Tetsufumi Ito &Shig Kuwada
Brod
alFig 9‐8
MSO: medial superior olive; LSO: lateral superior oliveNTB: nucleus of trapezoid body; IC: inferior colliculus
Binaural Basic Circuits
MSO Principle Cells
glutamate
Fusiform Bipolar Disc‐shaped Each dendrite innervated by a different side
MSO‐In situ hybridization
VGLUT1 VGLUT2 VIAAT NISSL
MSO
MNTB
LSOSPO
RPO
LSO MSO
MNTB
G
BB
B
L
L
H
H
EI - ILD EE - ITD
MSO Inputs and Synapses
E=Excitation (glutamate) ‐‐‐ I=Inhibition (glycine)
H=high frequencyL=low frequency
LNTBTO LSO
Unlike retinal targets, the cochlear nuclei contain maps of frequency, not location.
T
T + ITD
So how does the auditory system know ‘where’ a sound is coming from?
By comparing the interaural time differences (ITD) between the ears
How is this accomplished?...
ITD CODING
A
B
C
D
E
abcd eOutputPlace Code
Left InputTime Code
Right InputTime Code
A
B
C
D
E
abcd eOutputPlace Code
Left InputTime Code
Right InputTime Code
MSO "peak" unit LSO "trough" unit
ExcitationInhibition
A C
D E
B
ITD ITD
LSO
E
E E
I
Figure 14.2
MSO
MSO creates a response to interaural time differences
Binaural Responses in MSO
MSO Summary Cytoarchitecture – Laminar stack Neuron types ‐ glutamate Inputs – Spherical bushy AVCN Outputs – Inferior colliculus Synapses – Excitatory glutamate
Basic Circuit –Coincidence detector for ITD
Brod
alFig 9‐8
MSO: medial superior olive; LSO: lateral superior oliveNTB: nucleus of trapezoid body; IC: inferior colliculus
Binaural Basic Circuits
LSO‐In situ hybridization
VGLUT1 VGLUT2 VIAAT NISSL
MSO
MNTB
LSOSPO
RPO
Calyx of Held
CalyxVGLUT1
LSO MSO
MNTB
G
BB
B
L
L
H
H
EI - ILD EE - ITD
LSO Inputs and Synapses
E=Excitation (glutamate) ‐‐‐ I=Inhibition (glycine)
H=high frequencyL=low frequency
A
B
C
D
E
abcd eOutputPlace Code
Left InputTime Code
Right InputTime Code
A
B
C
D
E
abcd eOutputPlace Code
Left InputTime Code
Right InputTime Code
MSO "peak" unit LSO "trough" unit
ExcitationInhibition
A C
D E
B
ITD ITD
MSO
E
E E
I
Figure 14.2
LSO
Binaural Responses in Superior Olive
ITDs work only for the low frequency components of sound
What about higher frequencies?
The sound shadow cast by the head produces interaural level differences
How is this comparison made?...
Louder Softer
ILD CODING
LSO vs MNTB Response to ILD
LSO Creates ILD Responses
EI inputs to LSO When sound is louder in ipsilateral ear, LSO neurons fire action potentials
When sound is louder in the contralateral ear, LSO neurons are inhibited
LSO MSO
MNTB
G
BB
B
L
L
H
H
EI - ILD EE - ITD
EI
Brod
alFig 9‐8
MSO: medial superior olive; LSO: lateral superior oliveNTB: nucleus of trapezoid body; IC: inferior colliculus
Output of SOC to IC
glutamate
glycine
LSO Summary Cytoarchitecture – S‐shaped laminae Neuron types – glutamate or glycine Inputs – Spherical bushy AVCN ipsilateral MNTB principle cells driven by globular bushy cells
contralateral Outputs – Bilateral inferior colliculus Synapses – Excitatory glutamate from ipsilateral Inhibitory glycine from MNTB
Basic Circuit – Coincidence detector for ILD and ITD
Periolivary‐In situ hybridization
VGLUT1 VGLUT2 VIAAT NISSL
MSO
MNTB
LSOSPO
RPO
Periolivary Nuclei
CONTRLATERALVCN
IPSILATERALVCN
VMPO
VLPO
SPO
DPO
Basic Circuit of SPON
Other Inputs: Descending System
Periolivary Nuclei Summary
Neurons use GABA, glycine, or acetylcholine Inputs from cochlear nucleus, one side only Monaural Output to IC: SPON Cochlear nucleus: VNTB & VLPO Cochlea ‐medial OCB: VMPO & other Cochlea ‐lateral OCB: VLPO & other
