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An optical imaging study on language recognition in the first year of life. Susan Hespos Northwestern University. Developmental Cognitive Neuroscience. Many neuroimaging methods can be applied to the developing human brain. Where and when particular patterns of neural activity occur.

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an optical imaging study on language recognition in the first year of life

An optical imaging study on language recognition in the first year of life

Susan Hespos

Northwestern University

developmental cognitive neuroscience
Developmental Cognitive Neuroscience
  • Many neuroimaging methods can be applied to the developing human brain
  • Where and when particular patterns of neural activity occur
  • How does this method contribute to knowledge of language acquisition?
why do imaging on infants
Why do imaging on infants?
  • We can look at continuity and change over time
      • Is it the same behavior outcome and different underlying mechanisms?
      • Are there different behavior outcomes and the same underlying mechanism?
  • Rich data, low task demands, holding the task constant across ages
slide4

Behavioral

Research

Imaging

Research

Phonetic contrasts

Statistical learning

Language-specific perception & production

Infants

Bilingual activation

Phonetic contrasts

Sentence

comprehension

Phonetic contrasts

Statistical learning

Language-specific perception & production

Adults

near infrared spectroscopy nirs
Near Infrared Spectroscopy (NIRS)
  • Based on pulse oximetry
  • Measurement of temporal changes in both oxyhemoglobin and deoxyhemoglobin
about nirs
Pros

Pulse ox technology is used widely

No injections

Silent

Minimal restraint

Records oxy and deoxy

Portable

Cons

Measures surface cortical only

Not many users yet

Analyses techniques vary

About NIRS
previous research using nirs on infants
Previous research using NIRS on infants
  • Baird et al. (2002)
    • Longitudinal 5 to 12 month olds
    • Piagetian search tasks
    • Significantly more frontal activity after success
  • Taga et al. (2003)
    • 2 to 4 month olds
    • Occipital areas show increase to flickering checker
  • Peña et al. (2003)
    • Neonates sleeping
    • LH superiority to speech, but not backward speech or silence
our questions
Our Questions
  • Is there LH superiority to language stimuli over the course of the first year?
  • Are there non-language stimuli that show LH superiority?
  • Are the responses similar across development (e.g., young vs. old infants compared to adults)?
experiment
Experiment
  • Participants
    • Infants n = 80
      • 40 – ‘young’ (3 to 7.5 months)
      • 40 – ‘old’ (7.5 to 10.5 months)
    • 16 adults
  • 5 possible conditions
      • English, Scrambled English
      • Korean, Scrambled Korean
      • Tone (continuous sine wave)
scrambled conditions
Scrambled Conditions
  • Very speech like
    • Preserved segmental consonants and vowels
  • Not like speech at all
    • Violates continuity and prosody
comparison to pe a et al
Comparison to Peña et al.
  • State
  • Age
  • DV
  • Path length
  • Language
  • Stimuli features
slide15

ENG

ENG

ENG

16 sec

24 sec

32 sec

KOR

KOR

KOR

16 sec

24 sec

32 sec

SCR

ENG

SCR

ENG

SCR

ENG

16 sec

24 sec

32 sec

SCR

KOR

SCR

KOR

SCR

KOR

16 sec

24 sec

32 sec

TON

TON

TON

16 sec

24 sec

32 sec

slide17

Male infant

Female infant

Oxy

Total

Deoxy

slide18

Infants hearing English

3.5

3

2.5

2

upper

Activation

lower

1.5

Number of Voxels w/Sig

1

0.5

0

Left

Right

Hemisphere

slide19

Infants hearing English

3.5

3

2.5

2

Number of Voxels w/Sig

upper

Activation

lower

1.5

1

0.5

0

Left

Right

Hemisphere

slide20

Infants hearing Scrambled English

3.5

3

2.5

2

upper

Activation

lower

Number of voxels w/Sig

1.5

1

0.5

0

Left

Right

Hemisphere

slide21

Infants hearing English

Infants hearing Scrambled English

3.5

3.5

3

3

2.5

2.5

2

2

Number of Voxels w/Sig

upper

Number of voxels w/Sig

upper

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

slide22

Infants hearing Korean

3.5

3

2.5

2

upper

Activation

lower

Number of Voxels w/ Sig

1.5

1

0.5

0

Left

Right

Hemisphere

slide23

Infants hearing English

Infants hearing Scrambled English

3.5

3.5

3

3

2.5

2.5

2

2

Number of Voxels w/Sig

upper

Number of voxels w/Sig

upper

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

Infants hearing Korean

3.5

3

2.5

2

upper

Number of Voxels w/ Sig

Activation

lower

1.5

1

0.5

0

Left

Right

Hemisphere

slide24

Infants hearing Scrambled Korean

3.5

3

2.5

2

upper

Activation

lower

Number of voxels w/Sig

1.5

1

0.5

0

Left

Right

Hemisphere

slide25

Infants hearing English

Infants hearing Scrambled English

3.5

3.5

3

3

2.5

2.5

2

2

Number of Voxels w/Sig

upper

Number of voxels w/Sig

upper

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

Infants hearing Korean

Infants hearing Scrambled Korean

3.5

3.5

3

3

2.5

2.5

2

2

upper

Number of voxels w/Sig

upper

Number of Voxels w/ Sig

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

slide26

Infants hearing Tone

3.5

3

2.5

2

upper

Activation

lower

1.5

Number of Voxels w/ Sign

1

0.5

0

Left

Right

Hemisphere

slide27

Infants hearing English

Infants hearing Scrambled English

3.5

3.5

3

3

2.5

2.5

2

2

Number of Voxels w/Sig

upper

Number of voxels w/Sig

upper

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

Infants hearing Korean

Infants hearing Scrambled Korean

3.5

3.5

3

3

2.5

2.5

2

2

upper

Number of voxels w/Sig

upper

Number of Voxels w/ Sig

Activation

Activation

lower

lower

1.5

1.5

1

1

0.5

0.5

0

0

Left

Right

Left

Right

Hemisphere

Hemisphere

Infants hearing Tone

3.5

3

2.5

2

upper

Number of Voxels w/ Sig

Activation

lower

1.5

1

0.5

0

Left

Right

Hemisphere

infant results
Infant Results
  • LH superiority across all language conditions
  • Optical imaging can detect differences in auditory cortex
    • Across conditions
    • Between hemispheres
    • Between groups of channels
age difference in infants
Age difference in infants
  • Young infants: most activation to English+Scrambled Eng compared to other conditions
  • Older infants: most activation to straight compared to scrambled and tone conditions

Young Infants

Old Infants

3.5

3

2.5

Average # of Voxels

Showing sig activation

2

1.5

1

0.5

0

Sc

Eng

Sc

Kor

Sc

Eng

Sc

Kor

Eng

Kor

Ton

Eng

Kor

Ton

slide30

Adults hearing English

Adults hearing Scrambled English

3.5

3.5

3

3

2.5

2.5

upper

2

2

upper

Number of Voxels w/ Sig

Number of Voxels w/ Sig

lower

Activation

Activation

1.5

lower

1.5

1

1

0.5

0.5

0

0

Right

Left

Left

Right

Hemisphere

Hemisphere

Adults hearing Scrambled Korean

3.5

3

2.5

upper

2

Number of Voxels w/ Sig

lower

Activation

1.5

1

0.5

0

Left

Right

Hemisphere

Adults hearing Korean

3.5

3

2.5

upper

2

Number of Voxels w/ Sig

lower

Activation

1.5

1

0.5

0

Left

Right

Hemisphere

Adults hearing Tone

3.5

3

2.5

2

upper

Number of Voxels w/ Sig

Activation

lower

1.5

1

0.5

0

Left

Right

Hemisphere

adult results
Adult Results
  • LH superiority to English and Korean
  • RH superiority to Scrambled conditions
  • Bilateral and low activation to Tone
comparisons between infants and adults
Comparisons between infants and adults
  • Language conditions only
    • Young infants are significantly different from adults
    • Old infants are not significantly different from adults

Young

Adults

4

4

3.5

3.5

3

3

2.5

2.5

English

English

2

2

Korean

Korean

1.5

1.5

1

1

0.5

0.5

0

0

Left Hemisphere

Right Hemisphere

Left Hemisphere

Right Hemisphere

This comparison collapses across straight/scrambled factor

individual differences
Individual differences
  • English (n = 62 infants)
    • LH Superiority: 71%
    • RH Superiority: 11%
    • Equal activation: 2%
    • No activation: 16%
discussion
Discussion
  • There is LH superiority to language over the course of the first year
  • Young infants show LH superiority to our scrambled stimuli
  • Developmental differences are measurable across infants and adults
speculations
Speculations
  • Prosodic sensitivity is not in place by 6 months (Jusczyk et al. 1993; 1994)
    • Perhaps that is related to the young infants LH superiority across all language conditions
  • Prosodic sensitivity is in place by 7.5 months (Jusczyk et al. 1999; Newsome & Jusczyk, 1995)
    • Perhaps older infants and adults are sensitive to violations of the spectral quality and prosody and responded differently to the straight versus scrambled speech.
  • Our findings are consistent with Native Language Neural Commitment (Kuhl, 2004)
thanks
Thanks!
  • John Gore, Chris Cannestraci, and Sohee Park at Vanderbilt University
  • Anna Lane for heroic efforts in data analyses!
  • McDonnell Foundation and Discovery grants
slide38

7, 23 old females

Awake

Asleep

English

Korean

slide40

Same male, same visit

Awake

Asleep

Korean

Scr

Korean

slide42

T

o

n

a

l

E

n

g

l

i

s

h

K

o

r

e

a

n

Hemodynamic

Curves

A

d

u

l

t

A

v

e

r

a

g

e

1

2

1

0

8

6

4

2

0

-

2

-

4

-

6

-

5

0

5

1

0

1

5

2

0

2

5

T

i

m

e

mohinish s question

1

2

1

0

A

d

u

l

t

p

r

o

b

e

s

I

n

f

a

n

t

p

r

o

b

e

s

8

6

4

2

0

-

2

-

4

-

6

-

8

-

5

0

5

1

0

1

5

2

0

2

5

T

i

m

e

Mohinish’s Question
what does the data look like
What does the data look like?
  • 4 parts of the signal
    • Heart rate
    • Respiration
    • Mayer wave
    • Functional change
  • Analysis
    • Modified Beer Lambert Law
      • Known distance light traveled through
      • Same absorbency assumed
experiment 1
Experiment 1
  • Participants
    • Cross sectional 39
      • 11 – 4 to 6 months (M = 5 months)
      • 14 – 7 to 9 months (M = 8 months)
      • 14 adults (M = 23 years)
    • Longitudinal
      • 2 infants 8 visits between 1 and 3 months
    • Additional
      • 18 did one condition but not both
      • 3 fussed out
experiment 11
Experiment 1
  • Apparatus
    • Hitachi ETG 100, 780 and 830 nm
    • 24 source/detector pairs
    • Path length for adults 3 cm baby 2 cm
  • Data Analysis
    • Filtering done in Matlab, down sampling, applied modified Beer-Lamberts
    • Brain Voyager QX used for linear drift correction and statistical analysis
slide48

Stimuli and Design

Motor Cortex

Visual Cortex

Activity

No Activity

Vibrating Toy

Activity

No Activity

Visual Flicker

individual results
Individual Results

4-6 mos female

4-6 mos male

7-9 mos female

7-9 mos male

characteristics of the bold response for different cortical areas
Characteristics of the BOLD response for different cortical areas

4-6 mos

7-9 mos

Adult

Motor

Mean time to peak 6s after stimulus onset

Visual

Mean time to peak 13s after stimulus onset

individual differences1
Individual differences

4-6 mos

7-9 mos

Adult

Motor

Visual

discussion1
Discussion
  • Global similarities across ages in motor and visual stimulation
  • All participants showed increase blood flow due to stimulation
  • Nuanced differences across ages
  • Individual data suggest quantity of variance
cheers
Cheers
  • We tested 4x as many subjects
  • Infant friendly design - low drop out rate and better quality data
  • Design that doesn’t require ‘rest’
  • Double dissociation in the design