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Home , Cochlear nerve, Cochlear nucleus, Dorsal cochlear nucleus, Trapezoid body

Processing in The

Alan R. Palmer

Medical Research Council Institute of Research University Park Nottingham NG7 2RD, UK

The Auditory Nervous System

Cortex Cortex

MGB Medial Geniculate Body

Excitatory GABAergic IC Glycinergic

DNLL Nuclei of the

Lateral Lemniscus Cochlear Nucleus DCN

PVCN MSO Lateral Superior Olive AVCN Medial Superior Olive MNTB Medial Nucleus of the Superior Olive

The cochlear nucleus is the site of termination of fibres of the auditory

Cochlear Nucleus

Auditory Nerve

Cochlea

1 Frequency

Tonotopicity

Basilar membrane

Inner

Auditory nerve Fibre To the

Each auditory-nerve fibre responds only to a narrow range of frequencies

Tuning curve

Evans 1975

2 Palmer and Evans 1975

There are many overlapping single-fibre tuning curves in the auditory nerve

Audiogram

Palmer and Evans 1975

Tonotopic Organisation

Lorente - 1933

3 Tonotopic Organisation

Base Anterior Cochlea Characteristic Frequency

Hair Cells

Auditory Nerve Apex Cochlear Nucleus Posterior

Tonotopic projection of auditory-nerve fibers into the cochlear nucleus

Ryugo and Parks, 2003

The cochlear nucleus: the first auditory nucleus in the CNS Best frequency

Position along electrode track (mm)

Evans 1975

4 stellate (DCN)

Inhibitory Synapse

Excitatory Synapse DAS to inferior colliculus cartwheel fusiform

SUPERIOR OLIVARY giant COMPLEX INFERIOR COLLICULUS

granule vertical vertical OCB AANN to CN & IC via TB golgi DORSAL ? COLUMN NUCLEUS ? VESTIBULAR to PPO NERVE to VNLL IAS to IC? to VNLL to MSO to DMPO, PPO MNTB, LNTB from DLPO via TB

PRI PRI-N CHOP-S ON-C spherical bushy globular bushy multipolar multipolar octopus

via TB to reticular pontine formation and deep SC (perhaps via collaterals to COCHLEAR NUCLEUS root neurone contralateral VNLL) ARP (after Meddis, Shackleton and Hewitt) II I Auditory Nerve

Physiological Classification of Cochlear Nucleus Neurones

5 LATERAL INHIBITION IN THE

120

110

100

90

80 vel (~dB SPL) (~dBvel e 70 Tone L Tone Inhibitory side band 60

50

40

Palmer 1977

Excitation

Inhibition Excitation

Excitation Inhibition Excitation Excitation

Inhibition

Stabler 1991

Inhibition Inhibition Inhibition

Stabler 1991

6 Sound Level

Auditory Nerve minimum thresholds

Kiang 1964

7 Saturated rate

Dynamic range Threshold

Spontaneous rate

Galambos and Davis 1943

Low threshold Guinea pig

High SR At each frequency, auditory nerve fibres differ in their spontaneous rate, input/output function and dynamic range - High threshold these covary. Low SR

Winter and Palmer

Cat

Sachs and Abbas 1974

8 Cochlear nucleus responses

Stabler 1991

Young

Timing Peri Stimulus Time Histograms

9 When a novel stimulus occurs within a frequency channel the discharge rate is immediately increased and then falls (adapts) over a few tens of milliseconds

Kiang et al. 1965

Winter and Palmer

10 Dorsal

Lesion

DCN AVCN

Lesion

PVCN Posterior Anterior 80 Pauser AN 64 Ventral 150 48 120 Pri 32 er bin 90 Fusiform 16 0 60 0 50 100 30 Globular bushy

Spikes p Stellate 0 0 50 100 Octopus

Spherical bushy Stellate

200 120 Chop-S Chop-T 160 96 120 72 140 230 240 180 80 48 Pri-N On On On 112 184 C 192 L 144 I 40 24 84 Auditory 138 144 108 0 0 Nerve 0 50 100 0 50 100 56 92 96 72 28 46 48 36 0 0 0 0 0 50 100 0 50 100 0 50 100 0 50 100 Time in ms

Temporal Responses of the Principal Neurones of the Cochlear Nucleus to pure tones

Types of neurones in the cochlear nucleus

11 Osen 1969

PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS

To medial superior olive: information about sound To inferior colliculus: information about pinna localisation using timing (and possibly time coding of speech) sound transformations

To lateral superior olive: information about sound localisation using interaural intensity

To medial nucleus of the trapezoid body: information Either commisural or to inferior colliculus about sound localisation using interaural intensity information about sound level and voice pitch

To inferior colliculus: information about complex sounds (possibly place coding of speech)

Input from

Bushy Cells

Lorente de Nó

12 The discharges of cochlear nerve fibres to lowlow-- frequency sounds are not random; they occur at particular times (phase locking).

Evans (1975)

Alt Tab

Enhancement of synchronization in Globular Bushy Cells

Joris et al 1994

13 Enhancement of synchronization in Spherical Bushy Cells

Joris and Smith 2008

PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS

To medial superior olive: information about sound To inferior colliculus: information about pinna localisation using timing (and possibly time coding of speech) sound transformations

To lateral superior olive: information about sound localisation using interaural intensity

To medial nucleus of the trapezoid body: information Either commisural or to inferior colliculus about sound localisation using interaural intensity information about sound level and voice pitch

To inferior colliculus: information about complex sounds (possibly place coding of speech)

Input from cochlear nerve

Type T Multipolar Cells

Lorente de Nó

14 BF Tones 160 140 120 +50 dB 100

10.0 80 9.0 Spikes/bin 60 8.0 7.0 40 6.0 20 5.0 4.0 0 0 102030405060708090100110 3.0 2.0 Post Stimulus Onset Time (ms) 1.0 160 0.0 140 120 +20 dB 100 80 ikes/bin p

S 60 40 20 11.77 kHz Chop-T 0 0 102030405060708090100110 BF Tones Noise Post Stimulus Onset Time (ms) 7 7 7 7

6 6 6 6

5 5 5 5

4 4 4 4

3 3 3 3 Spikes/Stimulus Spikes/Stimulus 2 2 Spikes/Stimulus 2 2 Spikes/Stimulus

1 1 1 1

0 0 0 0 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 Level (dB) Level (dB) 26810

Transient Chopper Unit BF 11.77 kHz

26810

BF Tones 160 140 120 +50 dB 100 80

Spikes/bin 60 > 10.0 9.0 - 10.0 40 8.0 - 9.0 20 7.0 - 8.0 6.0 - 7.0 0 5.0 - 6.0 0 102030405060708090100110 4.0 - 5.0 Post Stimulus Onset Time (ms) 3.0 - 4.0 2.0 - 3.0 1.0 - 2.0 0.0 - 1.0

120 100 +20 dB 80

60

Spikes/bin 40 BF Tones Noise 20 14 14 12 12 0 0 102030405060708090100110 12 12 10 10 10 10 Post Stimulus Onset Time (ms) 8 8 8 8 6 6 6 6 4 4 Spikes/Stimulus Spikes/Stimulus

4 4 Spikes/Stimulus Spikes/Stimulus 2 2 2 2 Chop-S 19.6 kHz 0 0 0 0 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 Level (dB) Level (dB)

21201

15 Generation of vowel sounds

At low sound levels steady-state vowels are well represented in the mean discharge rate of the population of auditory nerve fibres.

Sachs and Young, 1979

At higher sound levels the representation of the formant frequencies becomes less distinct.

Sachs, Young and Colleagues

16 Theoretical computations, based on optimally weighting * the different spontaneous * rate popu lations, rev eal that mean rate alone may contain sufficient information even at high sound levels. *

Delgutte, 1996

Selective listening

Lai, Winslow and Sachs, 1994

Two populations of cochlear nucleus stellate cells retain vooeowel form atant information in their discharge rate at high sound levels

Blackburn and Sachs, 1990

17 PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS

To medial superior olive: information about sound To inferior colliculus: information about pinna localisation using timing (and possibly time coding of speech) sound transformations

To lateral superior olive: information about sound localisation using interaural intensity

To medial nucleus of the trapezoid body: information Either commisural or to inferior colliculus about sound localisation using interaural intensity information about sound level and voice pitch

To inferior colliculus: information about complex sounds (possibly place coding of speech)

Input from cochlear nerve

Type D Multipolar Cells (commisurals)

D-stellate cells in the VCN

Cant and Gaston - 1982 Oertel’s Group - 1990

Physiological Responses before injection

BF Tones Noise 160 100 140 120 +50 dB 80 100 40 dB 60 80

Spikes/bin 60 40

Spikes/bin 10.0 40 20 9.0 20 8.0 0 7.0 0 0 102030405060708090100110 0 102030405060708090100110 6.0 Post Stimulus Onset Time (ms) 5.0 Post Stimulus Onset Time (ms) 4.0 3.0 100 70 2.0 60 1.0 80 0.0 50 20 dB 60 +20 dB 40 pikes/bin 40 pikes/bin 30 S S 20 20 10

0 0 0 102030405060708090100110 0 102030405060708090100110 Post Stimulus Onset Time (ms) Post Stimulus Onset Time (ms) BF Tones Noise 2.5 2.5 5 5

2.0 2.0 4 4

1.5 1.5 3 3

1.0 1.0 2 2 Spikes/Stimulus Spikes/Stimulus Spikes/Stimulus Spikes/Stimulus 0.5 0.5 1 1

0.0 0.0 0 0 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 Level (dB) Level (dB) Onset-C Unit BF 6.29 kHz 28204

18 Physiological Responses after injection

BF Tones 120 Noise 100 100 80 80 +50 dB 40 dB 60 60

Spikes/bin 40 40 Spikes/bin 10.0 20 20 9.0 8.0 0 0 102030405060708090100110 0 7.0 Post Stimulus Onset Time (ms) 0 102030405060708090100110 6.0 Post Stimulus Onset Time (ms) 5.0 4.0 3.0 2.0 160 120 1.0 140 100 0.0 120 20 dB

n 80 100 +20 dB 80 60 pikes/bi pikes/bin

S 60 S 40 40 20 20 0 0 0 102030405060708090100110 0 102030405060708090100110 Post Stimulus Onset Time (ms) Post Stimulus Onset Time (ms) BF Tones Noise 4 4 5 5

4 4 3 3

3 3 2 2 2 2 Spikes/Stimulus Spikes/Stimulus Spikes/Stimulus Spikes/Stimulus 1 1 1 1

0 0 0 0 100 90 80 70 60 50 40 30 20 10 0 100 90 80 70 60 50 40 30 20 10 0 Level (dB) Level (dB) Onset-C Unit BF 6.29 kHz 28204

21208

Onset-C Unit BF 6.29 kHz 28204

19 Onset-C Unit BF 6.29 kHz 28204

Onset unit

Chopper unit

Primarylike unit

Cochlear nerve fibre

Kim and Leonard, 1988

Kim and Leonard, 1988

20 Octopus Cells

Octopus Cells

Oertel et al 2000

Octopus Cells

Oertel et al 2000

21 PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS

To medial superior olive: information about sound To inferior colliculus: information about pinna localisation using timing (and possibly time coding of speech) sound transformations

To lateral superior olive: information about sound localisation using interaural intensity

To medial nucleus of the trapezoid body: information Either commisural or to inferior colliculus about sound localisation using interaural intensity information about sound level and voice pitch

To inferior colliculus: information about complex sounds (possibly place coding of speech)

Input from cochlear nerve

Pinna Cue Pathway

Dorsal Cochlear Nucleus

Bipolar

Large Multipolar

Giant

Fusiform

Dorsal Cochlear Nucleus

Oertel and Young, 2004

22 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

23 Input from somatosensory system possibly involved in compensation for pinna and head position

Cells sensitive to sharp spectral notches

Young (Baltimore)

24 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 is tonotopically organized.

The cochlear nucleus contains several major cell types that project to other brain areas.

As a result of their interconnections, biophysics and input from the auditory nerve these cell groups reprocess the auditory nerve activity for different features of the incoming sounds.

PARALLEL PROCESSING OF INFORMATION IN THE COCHLEAR NUCLEUS

To medial superior olive: information about sound To inferior colliculus: information about pinna localisation using timing (and possibly time coding of speech) sound transformations

To lateral superior olive: information about sound localisation using interaural intensity

To medial nucleus of the trapezoid body: information Either commisural or to inferior colliculus about sound localisation using interaural intensity information about sound level and voice pitch

To inferior colliculus: information about complex sounds (possibly place coding of speech)

Input from cochlear nerve

25