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Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp [email protected] HowYourBrainWorks.net

Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp [email protected] HowYourBrainWorks.net

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Page 1: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Auditory Neuroscience 1Spatial Hearing

Systems Biology Doctoral Training ProgramPhysiology course

Prof. Jan [email protected]

HowYourBrainWorks.net

Page 2: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Hearing: an impossible task!

Page 3: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

http://auditoryneuroscience.com/foxInSnow

Page 4: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Interaural Time Difference (ITD) Cues

ITD

ITDs are powerful cues to sound source direction, but they are ambiguous (“cones of confusion”)

Page 5: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Front-Back Ambiguity and Phase Ambiguity

http://auditoryneuroscience.com/ear/bm_motion_2

Page 6: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Interaural Level Cues (ILDs)

Unlike ITDs, ILDs are highly frequency dependent. At higher sound frequencies ILDs tend to become larger, more complex, and hence potentially more informative.

ILD at 700 Hz

ILD at 11000 Hz

Page 7: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Spectral (Monaural) Cues

Page 8: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Adapting to Changes in Spectral Cues

Hofman et al. made human volunteers localize sounds in the dark, then introduced plastic molds to change the shape of the concha. This disrupted spectral cues and led to poor localization, particularly in elevation.

Over a prolonged period of wearing the molds, (up to 3 weeks) localization accuracy improved.

Page 9: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

EI neuron

Page 10: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Phase locking improves in the cochlear nucleus

Sphericalbushy

cell

Sphericalbushy

cell

Endbulbof Held

Endbulbof Held

Auditory nervefiber

Auditory nervefiber

Page 11: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

EE neuron

Page 12: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

The Jeffress model: mapping ITDs in the brain?

http://auditoryneuroscience.com/topics/jeffress-model-animation

Page 13: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

ITD tuning varies with sound frequency: no map?

McAlpine and colleagues

Page 14: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

The Auditory Pathway

M GB

IC

NLL

SOC

CN

Cor

tex

C och lea

M GB

IC

NLL

SOC

CN

Cortex

C och lea

Bra

inst

emM

idbr

ain

CN, cochlear nuclei; SOC, superior olivary complex; NLL, nuclei of the lateral lemniscus; IC, inferior colliculus; MGB, medial geniculate body.

Page 15: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Lesion Studies Suggest Important Role for A1

Jenkins & Merzenich, J. Neurophysiol, 1984

Page 16: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Binaural Frequency-Time Receptive Field

Page 17: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Linear Prediction

of Responses

-5 0 5 10

1

4

16

dB

1

4

16

Fre

qu

enc

y [k

Hz]

r(t) = i1(t-1) w1(1) + i1(t-2) w1(2)+ ...+ i2(t-1) w2(1) + i2(t-2) w2(2)+ ...+ i3(t-1) w3(1) + i2(t-2) w3(2)+ ...

Latency

FTRF “w matrix”

Input“i vector”

01002000

0.5

1re

spo

nse

ms

Page 18: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

01002000

0.5

1

resp

on

se

ms 0 100 2000

200

rate

(H

z)

ms

-5 0 5 10

1

4

16

dB

1

4

16

Left and Right Ear Frequency-Time Response

FieldsVirtual Acoustic Space Stimuli

Fre

qu

en

cy

[kH

z]

a

c

d

e

f

b

C81

-180 -120 -60 0 60 120 180Azim [deg]

-60

0

60

Ele

v [d

eg]

Ele

v [

deg

]

Predicting Space from Spectrum

Schnupp et al Nature 2001Schnupp et al Nature 2001

Page 19: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

“Higher Order” Cortical Areas

In the macaque, primary auditory cortex(A1) is surrounded by rostral (R), lateral (L), caudo-medial (CM) and medial “belt areas”.

L can be further subdivided into anterior, medial and caudal subfields (AL, ML, CL)

Page 20: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Are there “What” and “Where” Streams in Auditory Cortex?

Some reports suggest that anterior cortical belt areas may more selective for sound identity and less for sound source location, while caudal belt areas are more location specific.

It has been hypothesized that these may be the starting positions for a ventral “what” stream heading for inferotemporal cortex and a dorsal “where” stream which heads for postero-parietal cortex.

AnterolateralBeltAnterolateralBelt

CaudolateralBeltCaudolateralBelt

Page 21: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

A “Panoramic” Code for Auditory Space?

Middlebrooks et al.found neural spike patterns to vary systematically with sound source direction in a number cortical areas of the cat (AES, A1, A2, PAF).

Artificial neural networks can be trained to estimate sound source azimuth from the neural spike pattern.

Spike trains in PAF carry more spatial information than other areas, but in principle spatial information is available in all auditory cortical areas tested so far.

Page 22: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

-100

-50

0

50

dB/a/ /e/ /u/ /i/

200 Hz

-100

-50

0

50

dB

336 Hz

-100

-50

0

50

dB

565 Hz

0 5000 10000-100

-50

0

50

dB

Hz0 5000 10000

Hz0 5000 10000

Hz0 5000 10000

Hz

951 Hz

-100

-50

0

50

dB/a/ /e/ /u/ /i/

200 Hz

-100

-50

0

50

dB

336 Hz

-100

-50

0

50

dB

565 Hz

0 5000 10000-100

-50

0

50

dB

Hz0 5000 10000

Hz0 5000 10000

Hz0 5000 10000

Hz

951 Hz

Artificial Vowel Sounds

Bizley et al J Neurosci 2009 29:2064Bizley et al J Neurosci 2009 29:2064

Page 23: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Responses to Artificial Vowels in Space

Pit

ch (

Hz)

Vowel type (timbre)

Bizley et al J Neurosci 2009 29:2064Bizley et al J Neurosci 2009 29:2064

Page 24: Auditory Neuroscience 1 Spatial Hearing Systems Biology Doctoral Training Program Physiology course Prof. Jan Schnupp jan.schnupp@dpag.ox.ac.uk HowYourBrainWorks.net

Azimuth, Pitch and Timbre Sensitivity in Ferret Auditory Cortex

Bizley et al J Neurosci 2009 29:2064Bizley et al J Neurosci 2009 29:2064