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


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


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


• 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


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?)


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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