Tone deafness: a disorder of the mind’s ear

Tim Griffiths

Auditory Group, Newcastle UniversityCognitive Neurology Clinic, Newcastle General Hospital http://www.staff.ncl.ac.uk/t.d.griffiths/tdg.html

Supported by the Wellcome Trust (UK)

My work: Ordered and disordered acoustic worlds

The Ear

The person 2. NEUROLOGY Disordered sound patternanalysis

Speech Music Environmental Sound

The mind’s ear1. NEUROSCIENCEOrdering of sound pattern

How do we explain this?

Click picture for sound

Famous subjects with tone deafness

Che Guevara Milton Friedman

Tone deafness: some basic questions

His brain? His DNA?His neurons?His deficit?

Tone deafness: clues from neuroscience

Disorder in the pitch domain: music assessments show input problem with melody perception

What is pitch? How does the brain analyse pitch

and pitch patterns?

Pitch: normal mechanisms

Most neuroscience text books are wrong, and so was von Helmholtz

It’s not frequency Pitch is a percept not a stimulus

property

Pitch: normal mechanisms

von Helmholtz On the sensation

of tone (1862)

400Hz sine 400Hz fundamentalHarmonic 1 - 6

400Hz fundamentalHarmonic 4 - 6

frequency (kHz)

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Construction of the pitch percept

Common pitch explained better by time structure than frequency structure of stimulus

Pitch representation in the cortex

Functional imaging studies where brain activity measured when time structure of sound and associated pitch strength are varied

Individual data:Structural MRI Scan

noise - silencefixed pitch – noise

Individual fMRI data:Pitch Activation

Griffiths et al Nature Neurosci 1998, 2001Patterson et al Neuron 2002

Neural activity corresponding to the pitch of individual notes occurs in secondary auditory cortex

Accumulating evidence that activity in this area correlates with the perception of the pitch of sound and is not just a representation of the stimulus

Analogy to colour area in visual brain where perceived colour not stimulus wavelength represented

A ‘pitch centre’ in the auditory cortex?

Pitch sequences in the cortex

noise - silencefixed pitch – matched noise‘lively’ pitch – fixed pitch

NB NO TASK

Individual fMRI data:Pitch sequence

Griffiths et al Nature Neurosci 1998, 2001Patterson et al Neuron 2002

PET group data:Pitch sequenceNB TASK

Griffiths et al Neuroreport 1999

Pitch sequences in the cortex

Distributed networks beyond auditory cortex

For very high level processing (tonality) frontal processing only: no specific involvement of auditory cortex

Pitch: studies of stroke patients

Summary data Stewart et al Brain 2006

Tone deafness: clues from neuroscience

Normal functional imaging and studies of stroke patients broadly congruent

Analysis of the pitch of individual notes involves a pitch centre in secondary auditory cortex

Highly distributed networks for pitch sequence analysis beyond auditory cortex

If the deficit in melody perception in tone deafness is due to abnormal pitch pattern analysis, it is likely to be a problem with cortex beyond primary cortex

Tone deafness: what is the pitch deficit?

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Pitch change and pitch direction analysis Foxton et al Brain 2004

PitchChange 1

PitchChange 2

PitchDIRECTION

Tone deafness: what is the pitch deficit?

Abnormal perception of pitch direction

‘Bottom up’ basis for melody deficit: musicology

Deficient memory ‘trace’ for pitch –subjects unable to ‘keep track’ of pitch?

Tone deafness: Brain structure 1

White matter density: Montreal and Newcastle structural MRI dataHyde, Zatorre, Griffiths, Lerch and Peretz Brain 2006

Cortical thickness: Montreal and Newcastle structural MRI dataHyde, Lerch, Zatorre, Griffiths, Evans, Peretz (Human Brain Mapping Meeting 2006)

Tone deafness: Brain structure 2

Decreased white matter in right inferior frontal lobe

Increased cortical thickness in right inferior frontal lobe and right auditory cortex

Single-gene basis for both findings possible (connectivity deficit due to axonal migration disorder or cortex neuronal migration disorder)

Tone deafness: brain structure

Tone deafness: genes?

Family undergoing genetic analysis in NewcastleStewart, McDonald, Kumar, Chinnery, Griffiths (Music and Genetics Meeting Bologna 2007 )

Proband

Family

Single gene explanations unlikely to be universal explanation for tone deafness

Analogy with early onset Alzheimer’s disease (rare single-gene families and more common genes of major effect)?

Tone deafness : genes?

Apart from occasional disturbances of the peace, sufferers are generally useful members of society

Model system where we have the potential to explain a complex behaviour in terms of abnormal cortical development and connectivity

Other examples of disorders where abnormal connectivity implicated: schizophrenia, autism

Tone deafness: who cares?

Acknowledgements: Current (previous) group members and collaborators

Newcastle Auditory Group: Simon Baumann: Freya Cooper; (Jessica Foxton); Manon Grube; (Amanda Jennings); Katharina von Kriegstein; Sukhbinder Kumar; Tobias Overath; (Lauren Stewart)

Wellcome Centre for Imaging Neuroscience:Ray Dolan; Richard Frackowiak; Karl Friston

Cambridge University (CNBH): Roy Patterson Montreal (BRAMS): Krista Hyde; Isabelle

Peretz, Robert Zatorre