1 Processing in The Cochlear Nucleus Alan R. Palmer Medical Research Council Institute of Hearing Research University Park Nottingham NG7 2RD, UK IC Inferior Colliculus MGB Medial Geniculate Body Cortex Cortex The Auditory Nervous System Excitatory GABAergic Glycinergic DNLL Nuclei of the Lateral Lemniscus Lateral Lemniscus Lateral Superior Olive MSO MNTB Medial Nucleus of the Trapezoid Body Cochlea DCN PVCN AVCN Cochlear Nucleus Superior Olive Medial Superior Olive Cochlear Nucleus The cochlear nucleus is the site of termination of fibres of the auditory nerve Cochlea Auditory Nerve
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Processing in The Cochlear Nucleus
Alan R. Palmer
Medical Research Council Institute of Hearing ResearchUniversity Park
Nottingham NG7 2RD, UK
IC Inferior Colliculus
MGB Medial Geniculate Body
Cortex Cortex
The Auditory Nervous System
ExcitatoryGABAergicGlycinergic
DNLL Nuclei of the Lateral Lemniscus
Lateral Lemniscus
Lateral Superior OliveMSO
MNTBMedial Nucleus of the Trapezoid Body
Cochlea
DCN
PVCN
AVCN
Cochlear Nucleus
Superior Olive
Medial Superior Olive
Cochlear Nucleus
The cochlear nucleus is the site of termination of fibres of the auditory nerve
Cochlea
Auditory Nerve
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Frequency
Tonotopicity
Basilar membrane
Auditory nerve Fibre
Inner hair cell
To the brain
Each auditory-nervefibre responds only to
a narrow range of frequencies
Action potential
frequencies
Tuning curve
Evans 1975
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Palmer and Evans 1975
There are many overlapping single-fibre tuning curves in the auditory nerve
Audiogram
Palmer and Evans 1975
Lorente - 1933
Tonotopic Organisation
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AnteriorBaseCochlea
Basilar Membrane
Hair Cells
Tonotopic Organisation
Characteristic Frequency
PosteriorCochlear Nucleus
Auditory NerveApex
Spiral Ganglion
Tonotopic projection of auditory-nerve fibers into the cochlear nucleus
Ryugo and Parks, 2003
The cochlear nucleus: the first auditory nucleus in the CNS
via TB to reticular pontine formationand deep SC (perhaps via collaterals tocontralateral VNLL)
IAS to IC?
to PPO
to VNLL
from DLPO
PRI PRI-N CHOP-S ON-C
to CN & IC via TB
to DMPO, PPOMNTB, LNTBvia TB
to MSO to VNLL
COCHLEAR NUCLEUSARP (after Meddis, Shackleton and Hewitt)
Physiological Classification of Cochlear Nucleus Neurones
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120
80
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LATERAL INHIBITION IN THE DORSAL COCHLEAR NUCLEUSev
el (~
dB S
PL)
70
60
50
40
Tone
Le
Inhibitory side band
Palmer 1977
InhibitionExcitation
Excitation
Stabler 1991
Inhibition
Excitation
Excitation ExcitationInhibition
Inhibition Inhibition Inhibition
Stabler 1991
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Sound Level
Auditory Nerve minimum thresholds
Kiang 1964
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Saturated rate
Galambos and Davis 1943
Spontaneous rate
ThresholdDynamic range
At each frequency, At each frequency, auditory nerve fibres auditory nerve fibres
differ in their differ in their spontaneous ratespontaneous rate
High SR
Low threshold Guinea pig
spontaneous rate, spontaneous rate, input/output functioninput/output functionand dynamic range and dynamic range --
these covary.these covary.High thresholdLow SR
Winter and Palmer
Cat
Sachs and Abbas 1974
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Cochlear nucleus responses
Stabler 1991
Young
TimingPeri Stimulus Time Histogramsg
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When a novel stimulus occurs within a frequency channelthe discharge rate is immediately increased and then falls
(adapts) over a few tens of milliseconds
Kiang et al. 1965
Winter and Palmer
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er b
in Pri
Pauser
Fusiform
AnteriorPosterior
Dorsal
Ventral
DCN
Lesion
Lesion
AVCN
PVCN
AN
1632486480
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Spik
es p
Time in ms
Chop-T
OnIOnC OnL
Chop-S
Pri-N
Auditory Nerve
Octopus
Spherical bushy
Globular bushy
Fusiform
Stellate
Stellate
016
0 50 100
0 48 96
144192240
0 50 100 0 46 92
138184230
0 50 100 0 36 72108144180
0 50 100
0 40 80120160200
0 50 100
0 30 60 90
0 50 100
0 24 48 72 96120
0 50 100
0 28 56 84112140
0 50 100
Temporal Responses of the Principal Neurones of the Cochlear Nucleus to pure tones
Types of neurones in the cochlear nucleus
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Osen 1969
To medial superior olive: information about soundlocalisation using timing (and possibly time coding of speech)
To inferior colliculus: information about pinna sound transformations
To lateral superior olive: information about
PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS
Either commisural or to inferior colliculusinformation about sound level and voice pitch
To inferior colliculus: information about complex sounds (possibly place coding of speech)
Input from cochlear nerve
To lateral superior olive: information aboutsound localisation using interaural intensity
To medial nucleus of the trapezoid body: information about sound localisation using interaural intensity
Bushy Cells
Lorente de Nó
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The discharges of cochlear nerve fibres to lowThe discharges of cochlear nerve fibres to low--frequency sounds are not random; frequency sounds are not random;
they occur at particular times (they occur at particular times (phase lockingphase locking).).
Evans (1975)
Alt Tab
Enhancement of synchronization in Globular Bushy Cells
Joris et al 1994
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Enhancement of synchronization in Spherical Bushy Cells
Joris and Smith 2008
To medial superior olive: information about soundlocalisation using timing (and possibly time coding of speech)
To inferior colliculus: information about pinna sound transformations
To lateral superior olive: information about
PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS
Either commisural or to inferior colliculusinformation about sound level and voice pitch
To inferior colliculus: information about complex sounds (possibly place coding of speech)
Input from cochlear nerve
To lateral superior olive: information aboutsound localisation using interaural intensity
To medial nucleus of the trapezoid body: information about sound localisation using interaural intensity
At low sound levels steady-state vowels are well represented in the mean discharge rate ofmean discharge rate of
the population of auditory nerve fibres.
Sachs and Young, 1979
At higher sound levels the representation of the
formant frequenciesformant frequencies becomes less distinct.
Sachs, Young and Colleagues
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Theoretical computations, Theoretical computations, based on optimally weighting based on optimally weighting
the different spontaneous the different spontaneous rate pop lations re eal thatrate pop lations re eal that
*rate populations, reveal that rate populations, reveal that mean rate alone may contain mean rate alone may contain sufficient information even at sufficient information even at
high sound levels.high sound levels.
Delgutte, 1996
*
*
Selective listeningSelective listening
Lai, Winslow and Sachs, 1994
Two populations of cochlear nucleus
stellate cells retain vowel formant o e o a t
information in their discharge rate at high
sound levels
Blackburn and Sachs, 1990
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To medial superior olive: information about soundlocalisation using timing (and possibly time coding of speech)
To inferior colliculus: information about pinna sound transformations
To lateral superior olive: information about
PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS
Either commisural or to inferior colliculusinformation about sound level and voice pitch
To inferior colliculus: information about complex sounds (possibly place coding of speech)
Input from cochlear nerve
To lateral superior olive: information aboutsound localisation using interaural intensity
To medial nucleus of the trapezoid body: information about sound localisation using interaural intensity
D-stellate cells in the VCN
Type D Multipolar Cells (commisurals)
Cant and Gaston - 1982Oertel’s Group - 1990
Physiological Responses before injection
10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0
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60
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100
Spi
kes/
bin
0
20
40
60
80
100
120
140
160
0 10 20 30 40 50 60 70 80 90 100 110
Spi
kes/
bin
Post Stimulus Onset Time (ms)
30
40
50
60
70
Spi
kes/
bin
0
20
40
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80
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0 10 20 30 40 50 60 70 80 90 100 110
Spi
kes/
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Post Stimulus Onset Time (ms)
+50 dB
+20 dB
BF Tones
20 dB
40 dB
Noise
28204
0
20
0 10 20 30 40 50 60 70 80 90 100 110
S
Post Stimulus Onset Time (ms)
0
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20
0 10 20 30 40 50 60 70 80 90 100 110
S
Post Stimulus Onset Time (ms)
0.0
0.5
1.0
1.5
2.0
2.5
0102030405060708090100
Spi
kes/
Stim
ulus
Level (dB)
0.0
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1.0
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2.0
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Spi
kes/
Stim
ulus
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0102030405060708090100
Spi
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Stim
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Level (dB)
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Spi
kes/
Stim
ulus
Onset-C Unit BF 6.29 kHz
BF Tones Noise
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Physiological Responses after injection
10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0
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80
100
120
140
160
Spi
kes/
bin
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40
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Spi
kes/
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Post Stimulus Onset Time (ms)
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80
100
120
Spi
kes/
bin
0
20
40
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Spi
kes/
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Post Stimulus Onset Time (ms)
NoiseBF Tones
+50 dB
+20 dB 20 dB
40 dB
Onset-C Unit BF 6.29 kHz 28204
0
1
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3
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0102030405060708090100
Spi
kes/
Stim
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Level (dB)
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Spi
kes/
Stim
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0
1
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0102030405060708090100
Spi
kes/
Stim
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Level (dB)
0
1
2
3
4
5
Spi
kes/
Stim
ulus
0
20
40
60
0 10 20 30 40 50 60 70 80 90 100 110
S
Post Stimulus Onset Time (ms)
0
20
40
0 10 20 30 40 50 60 70 80 90 100 110
S
Post Stimulus Onset Time (ms)
BF Tones Noise
21208
Onset-C Unit BF 6.29 kHz 28204
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Onset-C Unit BF 6.29 kHz 28204
Onset unit
Chopper unit
Kim and Leonard, 1988
Primarylike unit
Cochlear nerve fibre
Kim and Leonard, 1988
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Octopus Cells
Octopus Cells
Oertel et al 2000
Octopus Cells
Oertel et al 2000
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To medial superior olive: information about soundlocalisation using timing (and possibly time coding of speech)
To inferior colliculus: information about pinna sound transformations
To lateral superior olive: information about
PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS
Either commisural or to inferior colliculusinformation about sound level and voice pitch
To inferior colliculus: information about complex sounds (possibly place coding of speech)
Input from cochlear nerve
To lateral superior olive: information aboutsound localisation using interaural intensity
To medial nucleus of the trapezoid body: information about sound localisation using interaural intensity
Pinna Cue Pathway
Bipolar
Large Multipolar
Dorsal Cochlear Nucleus
FusiformFusiform
GiantGiant
Dorsal Cochlear NucleusOertel and Young, 2004
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Temporal Responses (PSTHS) in Dorsal Cochlear Nucleus
Monaural spectral localization cues
Moore and King 1999
Responses of a Type IV DCN units to sharp spectral edges
Reiss and Young 2005
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Cells sensitive tosharp spectral notches
Input from somatosensory systempossibly involved in compensationfor pinna and head position
Young (Baltimore)
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Projections of the Major Cell Types of the Cochelar Nucleus
Malmierca and Smith 2006
Summary of Cochlear Nucleus Responses
The cochlear nucleus consists of three parts each of which istonotopically organized.
The cochlear nucleus contains several major cell types that projectto other brain areas.
As a result of their interconnections, biophysics and input fromthe auditory nerve these cell groups reprocess the auditory nerveactivity for different features of the incoming sounds.
To medial superior olive: information about soundlocalisation using timing (and possibly time coding of speech)
To inferior colliculus: information about pinna sound transformations
To lateral superior olive: information aboutsound localisation using interaural intensity
PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS
Either commisural or to inferior colliculusinformation about sound level and voice pitch
To inferior colliculus: information about complex sounds (possibly place coding of speech)
Input from cochlear nerve
sound localisation using interaural intensity
To medial nucleus of the trapezoid body: information about sound localisation using interaural intensity
