CNBH, PDN, University of Cambridge

Part II: Lent Term 2015: (

4

of 4)

Central Auditory Processing

Roy Patterson

Centre for the Neural Basis of Hearing Department of Physiology, Development and Neuroscience University of Cambridge

email [email protected]

Lecture slides on CamTools https://camtools.cam.ac.uk/portal.html

Lecture slides, sounds and background papers on http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/

CNBH, PDN, University of Cambridge

Contents/Progress

Act I: Communication sounds and the information in these sounds: message, S

s and S f

Act II: Behavioural evidence for the role of these different forms of information in the perception of communication sounds Act III: The processing of communication sounds in the early stages of the auditory system, and hypotheses about the representation of communication sounds in later stages of the auditory pathway Act IV: Brain imaging evidence concerning the representation of communication sounds in auditory cortex

CNBH, PDN, University of Cambridge

We have discussed a model of

auditory perception

that describes how sounds might be processed and represented at a sequence of stages in auditory system. All of the stages are mandatory and the order is crucial.

One representation is intended to simulate your initial Auditory Image of the incoming sound and it is central to the model.

Sensations like pitch and loudness are summary statistics calculated from the auditory image after it has been constructed. Speech and music perception are thought to be based on the patterns that arise in the auditory image.

So, this Auditory Image Model (AIM) predicts that we should find a hierarchy of processing modules in the auditory pathway.

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There is a sequence of neural centres in the auditory pathway.

Overview 2

The centres are separated by distances that are large relative the resolution of functional brain imaging (fMRI).

LL LL

The correspondence between the perceptual model and the anatomy suggests that (1) AIM could be useful when designing brain imaging studies of the auditory system

and (2)

the brain imaging data could help us locate the auditory image.

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Basilar membrane motion in the cochlea

Anatomy of the Auditory Pathway: 1

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Neural activity pattern in the cochlear nucleus

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Strobed temporal integration in the inferior colliculus?

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The initial auditory image in the MGB??

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Auditory Image The normalized auditory image in primary auditory cortex???

CNBH, PDN, University of Cambridge

The Auditory Image Model describes how the auditory system separates pulse-resonance sounds from noise, and how it normalizes and segregates the information about the pulse-rate (

S s

) and the resonance scale (

S f

) from the message.

So the brain imaging research focuses on finding evidence that the neural centres in the auditory pathway are involved in source segregation and normalization, and that the segregation and pulse rate normalization come before the resonance scale normalization.

Moreover, speech-specific analysis and music-specific analysis should occur in neural centres beyond, but not too far from, those associated with segregation of pulse resonance sounds from noise and their normalization.

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Brain Imaging with Simple Contrasts

Find two sounds that differ only in the perceptual property of interest (like pitch).

Scan the brain while people are listening, first to one sound and then to the other sound. Compare the brain activity produced by the two sounds looking for places where one sound produces more activity than the other.

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Brain imaging with Regular Interval Noise

Copy a sample of random noise; delay it by N ms; add it to the original noise.

The process emphasises time intervals of N ms in the sound and we hear a weak tone in the noise.

As you repeat the delay and add process, the relative strength of the tonal component of the sound increases.

RIN makes a good imaging stimulus because the sounds have similar distributions of energy over time and frequency.

In the experiment the RIN had 8 iterations of the delay and add process.

Noise Auditory Image D F G Neural activity patterns of Noise and RIN RIN J

B

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C Initial auditory images of noise and RIN G E H K

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Continuous Imaging vs Sparse Imaging

continuous imaging sparse imaging haemodynamic response to test stimulus haemodynamic response to scanner noise Difference in sensitivity to stimulus: positive negative [original figure by D. Hall, IHR, Nottingham]

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Imaging pitch and melody in the brain

On a given scan, the listener is presented a sound with a pulsing rhythm. The sound has

no pitch

(a noise), a

fixed pitch

(boring melody) or

changing pitch

(proper melody). Asked to listen for pattern in the sound, but no response is required.

http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf

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Sound minus silence contrast

CN CN IC

Parasagital view showing CN/ IC

AC IC AC AC

Axial view at level CN

MGB AC

40 35 30 25 20 15 10 5 0 T value

CN

Coronal view showing IC + superior temporal lobe Coronal view showing MGB + superior temporal lobe

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Left Hemisphere

saggital axial axial

Right Hemisphere

saggital coronal structural structural coronal

Group Analysis -78 noise-silence fixed-noise diatonic-fixed random-fixed 34.4

°

-10 10 78

x

34.4

°

Figure 2

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saggital axial axial saggital coronal structural structural coronal

Group analysis noise-silence fixed-noise tonic-fixed random-fixed -78 34.4

°

-10 10 78

x

34.4

°

CNBH, PDN, University of Cambridge

regular

equal energy click trains

irregular

Neural Activity Pattern

strong pitch

Auditory Image

no pitch

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anterior source: HG Effects of regularity and intensity in MEG posterior source: PT effect of

regularity

in anterior source effect of

level

in posterior source

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Conjecture Conjecture Conjecture

Proposed functional organisation of auditory cortex all sounds primary auditory cortex auditory cortex tonal sounds loudness lively pitch fixed pitch lively pitch

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http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf

http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/GPRUS02.pdf

Where does the auditory system segregate the information associated with S

s

, S

f

and the message?

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A damped sinusoid (12-ms period)

pulse ringing

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Auditory image of a damped sinusoid

6000 Hz pulse 1000 Hz ringing 100 Hz

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Stimuli for Phonology Study onset timing regular irregular

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Comparison of speech and music regions

z = 4mm mpmr-silence nvdvpv-mpmr mpmr-nvdvpv y = -24mm z = 4mm y = -17mm noise-silence fixed-noise lively-fixed z = -5mm z = -5mm

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Left Hemisphere

saggital axial

pitch

axial

Right Hemisphere

saggital

vtl AudIm

structural structural coronal

phonology Group analysis noise-silence fixed-noise tonic-fixed random-fixed -78 34.4

°

-10 10 78

x

34.4

°

CNBH, PDN, University of Cambridge

Conjecture Conjecture Conjecture

Proposed functional organisation of auditory cortex all sounds primary auditory cortex auditory cortex tonal sounds loudness lively pitch fixed pitch receptive phonology lively pitch

CNBH, PDN, University of Cambridge

Done!

Act I: the information in communication sounds (animal calls, speech, musical notes) Act II: the perception of communication sounds (the robustness of perception) Act III: the processing of communication sounds in the auditory system (signal processing) Act IV: the processing of communication sounds (anatomy, physiology, brain imaging)

CNBH, PDN, University of Cambridge

End of Act IV Thank you

Patterson, R.D., Uppenkamp, S., Johnsrude, I. and Griffiths, T. D. (2002). The processing of temporal pitch and melody information in auditory cortex.

Neuron

36 767-776.

http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/PUJG02.pdf

Gutschalk, A., Patterson, R.D., Rupp, A., Uppenkamp, S. and Scherg, M. (2002). Sustained magnetic fields reveal separate sites for sound level and temporal regularity in human auditory cortex.

NeuroImage

15 207-216.

http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/GPRUS02.pdf

Kriegstein, K. Von, Smith, D. R. R., Patterson, R. D., Kiebel, S. J. and Griffiths, T. D. (2010). “How the human brain recognizes speech in the context of changing speakers,”

J. Neuroscience

30(2) 629–638.

http://www.pdn.cam.ac.uk/groups/cnbh/teaching/lectures/KSPKGjn2010.pdf

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Cast list Roy Patterson, David Smith, Tim Ives, Ralph van Dinther

Centre for the Neural Basis of Hearing, Physiology Department, University of Cambridge

fMRI in Cambridge: Ingrid Johnsrude, Dennis Norris, Matt Davis, Alexis Hervais-Adelman, William Marslen-Wilson

MRC Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge

MEG in Heidelberg: Andre Rupp, Alexander Gutschalk, Stefan Uppenkamp, Michael Scherg MEG in Muenster: Katrin Krumbholz, Annemarie Preisler, Bernd Lutkenhoner

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Activation of voiced vs whispered speech x=+51 *** *** *** L y=-2 voiced > whispered whispered > voiced GPR varies > VTL varies TE1.2

TE1.1

voiced > silence whispered > silence

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Conjecture

saggital

Conjecture

axial axial

Conjecture

saggital coronal structural structural coronal

Group analysis noise-silence fixed-noise tonic-fixed random-fixed -78 34.4

°

-10 10 78

x

34.4

°

CNBH, PDN, University of Cambridge

Conjecture

saggital

Conjecture

axial axial

Conjecture

saggital coronal structural structural coronal

Group analysis noise-silence fixed-noise tonic-fixed random-fixed -78 34.4

°

-10 10 78

x

34.4

°