myeloarchitecture and intrinsic functional connectivity of auditory cortex in musicians with...

PhD examination Myeloarchitecture and Resting State Functional Connectivity of Auditory Cortex in Musicians with Absolute Pitch

Seung-Goo (“SG”) Kim Max Planck Institute for Human Cognitive and Brain Sciences

5 Jan 2017 Institute for PsychologyFaculty of Biosciences, Pharmacy, and PsychologyUniversity of Leipzig

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Overview

• Introduction: Absolute pitch (AP)

• Study #1: In-vivo cortical myelin mapping

• Study #2: Resting-state functional connectivity

• Discussion: Distributed processing of AP

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Introduction Absolute pitch

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What is absolute pitch (AP)?• Rare ability to recognize the name pitch without an external

reference [1].

• Related to early musical experience (4~7 year-old [2]) and a certain training method (“fixed-Do” than “movable-Do”) [3].

• Genetic factor: more APs in AP’s family [2]; Europeans (7%) vs. East-Asian (30%) in musicians [4].

• Sometimes make mistakes in octave recognition [1,4]: good at pitch chroma rather than pitch height.

[1] Miyazaki, 2004. [2] Baharloo et al., 1998. [3] Willson et al., 2012. [4] Miyazaki et al., 2012.4

What is pitch chroma?• “C3” • Pitch chroma:

Alphabetical label of 12 divisions of an octave (C, C#, D, D#, …)

• Pitch height: Octave index

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B2 C3 D3 E3 F3 G3 A3 B3 C4

C#3 D#3 F#3 G#3 A#3 C#4A#2

GarageBand, (C) Apple, Inc.

The 3rd octave The 4thThe 2nd

AP-test confusion matrix

Kim & Knösche, 2016. 6

• Perceptual processCategorization of pitch chroma

• Associative processVerbal/non-verbal labeling

Dichotomy of AP recognition

Levitin & Rogers, 2005. 7

Categorization

Labeling

• Temporal lobe (perceptual proc.)leftward asymmetry of planum temporale (PT) area [1]; higher activation in the left PT [2,3].

• Frontal lobe (associative proc.)thicker inferior frontal gyrus (IFG) [4]; higher activation in right dorsolateral prefrontal cortex (DLPFC) [3-5].

• Frontotemporal connectivityphase synchrony [6]; fractional anisotropy of superior longitudinal fasiculus (SLF) [7].

Previous neuroimaging findingsDLPFC

HGPT

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[1] Keenan et al., 2001. [2] Ohnishi et al., 2001. [3] Willson et al., 2009. [4] Dohn et al., 2015.[5] Zatorre et al., 1998. [6] Elmer et al., 2015. [7] Oechslin et al., 2009.

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HG: Heschl’s gyrus

But how does the AP work?

• How does the cortical regions and the connectivity between them contribute to the AP recognition?

> Multimodal imaging describing microscopic architecture might give us better ideas to construct a framework to explain how AP works.

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Myeloarchitecture of auditory cortex in musicians with AP

Study #1: Relaxometry at 7-T

10Kim & Knösche, 2016, Human Brain Mapping.

Intracortical myelination• Increases information transfer speed

(but not very much for short-range connections in gray matter)

• May reduce cross-talk between nearby axons, thus increasing specificity

• Prevents neuroplasticity after critical period of neurodevelopment (McGee et al., 2005)

Vogt, 1903

Cyto-architecture

Myelo-architecture

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Research questions

• Does the degree of cortical myelination in auditory cortex (related to the perceptual subprocess of AP) correlate with the acuity of AP?

• Is myelo-correlate of AP differentiable from that of the other psychoacoustic characteristics (e.g., frequency discrimination threshold)?

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Participants & imaging• Participants

• 8 AP musicians & 9 non-AP musicians categorized based on behavioral test of AP

• Cortical myelin mapping (7-T)

• MP2RAGE sequence for quantitative mapping of longitudinal relaxation rate (qR1), which strongly correlates with myelin content in the cortex

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In-vivo cortical myelin mapping

Kim & Knösche, 2016. 14

General linear model

• x was either:

• Absolute pitch group index

• Absolute pitch score (APS) = 1 - scaled ([0,1]) error,

• Frequency discrimination threshold (FDT) = -log10(Fm/F0)

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qR1 = β0 +ageβ1 + sexβ2 +ethnicityβ3 + xβ4 + ε

Absolute pitch score

HG

PT

STS

PPSTG

Frequency discrimination threshold

STG

HG

PT

STS

PP

Kim & Knösche, 2016. 16

Concave

Convex

Pitch chroma vs. pitch height

Warren et al., 2003.17

Planumpolare

Planumtemporale

Primary auditorycortex (overlap)

ChromaHeight

Kim & Knösche, 2016.

Dual pathway hypothesis (Rauschecker et al., 1995)

• Ventral (“what”): vs. dorsal (“where”) auditory pathways

• Spatially separated sensitivity to non-spatial (i.e. pitch) vs. spatial (i.e. location) information

Barret & Hall, 2006. 18

• Absolute recognition of pitch chroma (rather than height)

• Cortical myelin can increase specificity and suppress neuroplasticity

• Dual pathway hypothesis: non-spatial information (e.g. phoneme) via ventral pathway.

• Conjecture: Categorization of pitch chroma along the ventral pathway?

Categorical processing & ventral pathway

DLPFC

PT

HG

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PPVLPFC

Summary of Study #1

• We found: greater cortical myelin in the right planum polare (PP) in musicians with than without absolute pitch.

• We think: the right PP and its connection (ventral pathway) may be important in chromatic categorization.

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Resting-state functional connectivity of the ventral pathway in musicians with AP

Study #2: Resting-state fMRI at 3-T

21Kim & Knösche, 2016, In preparation.

Spontaneity of AP• Unintended recognition of pitch chroma of

environmental sound (e.g., cluttering of glasses, siren of ambulance) [1]

• Uncontrollable and instant perception (e.g., Stroop-like effect for incongruent pitch and pitch name [2,3])

• Spontaneous & automatic processing of AP could be reflected in BOLD signal during resting

[1] Miyazaki, 2004. [2] Itoh et al., 2005. [3] Schultz et al., 2013.22

Research questions

• Is the planum polare (PP) strongly coupled with other cortical regions that belong to the ventral pathway in musicians with AP?

• What about the planum temporale (PT) and the dorsal pathway?

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HG

DLPFC

PT

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VLPFCPP

HG: Heschl’s gyrus

Participants & imaging• Same participants: 8 AP musicians & 9 non-AP musicians

• Whole-brain functional images at 3-T

• Echo-planer imaging; 2.3-mm isovoxel; TR = 1.4 s; for 9.8-min resting

• Anatomical image at 3-T

• MPRAGE; 1-mm isovoxel

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Zero-lag cross-correlation

Kim & Knösche, In prep.25

Kim & Knösche, In prep.26

• Frequency-dependent connectivity (regardless of time lag)

• Averaged into 9 frequency bins with 50% overlap:[0, 20], [10, 30], [20, 40], …,[90, 110] mHz

Cross-coherence

General linear model

• FC was either:

• cross-correlation

• cross-coherence

• x was either:

• AP-group index (AP)

• AP score (APS)

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FC = β0 +motionβ1 + ethnicityβ2 + xβ3 + ε

AP/APS effect in correlation

28 Kim

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AP/APS effect in coherence

Kim

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Greater RSFC of the right PP• Ipsilateral STG, contralateral PP/STG:

adjacent/homologous regions via bilateral ventral streams [1]

• Bilateral STS: specialized auditory object recognition; e.g. voice recognition [2]

• Left IFG: verbal labeling of pitch chroma [3]

• Bilateral ACC, medial SFG: default-mode network [4]

[1] Upadhyay et al., 2008 [2] Belin et al., 2004. [3] Wengenroth et al., 2013. [4] Smith et al., 2009.30

What about the left dorsal pathway?

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• Leftward asymmetry of planum temporale (PT) [1]

• Greater rCBF/BOLD in the left PT during passive listening [2,3]

• Phase synchrony between PT and dorsal lateral prefrontal cortex (DLPFC) [4], superior longitudinal fasiculus [5]

★But not conclusive: the other studies also found volume/thickness/FA increase in the right STG/ILF [6,7].

[1] Schlaug et al., 1995. [2] Ohnishi et al., 2001. [3] Wilson et al., 2009. [4] Elmer et al., 2015.[5] Oechslin et al., 2009. [6] Wengenroth et al., 2013. [7] Dohn et al., 2015.

-log 1

0 min

P

RSFC seeding from planum temporale

Kim & Knösche, In prep.32

Summary of Study #2• We found: greater resting-state functional

connectivity (RSFC) of the the right planum polare (PP) with the anteroventral auditory network and the anteromedial network in musicians with absolute pitch (AP).

• We think: the ventral auditory pathway via the right PP may be crucial in AP processing (presumably in chromatic categorization).

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DiscussionDistributed processing of AP

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Main findings• Greater cortical myelin in the right planum

polare (PP) in musicians with absolute pitch

• Greater RSFC of the right PP in

• the right STG, the left PP/STG,

• the bilateral STS,

• the left IFG, and

• the bilateral ACC/SFG

• No difference in the left planum temporale.35

Distributed processing of APLeft dorsal pathway?(spatial processing?)

Kim & Knösche, In prep.36

Future directions• Topological organization for pitch chroma in APs

• Model-based encoding fMRI analysis

• Dynamics of frontotemporal network

• Effective connectivity in multimodal data (fMRI+MEG)

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Thank you for attention!

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