Superior olive anatomy-2013 - UConn HealthMNTB principle cells driven by globular bushy cells...

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