An optical imaging study on language recognition in the first year of life
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Transcript of 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
• Many neuroimaging methods can be applied to the developing human brain
• How does this method contribute to knowledge of language acquisition?
• Where and when particular patterns of neural activity occur
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
Infants
Adults
BehavioralResearch
ImagingResearch
Phonetic contrastsStatistical learningLanguage-specific perception & production
Bilingual activation Phonetic contrastsSentence comprehension
Phonetic contrastsStatistical learningLanguage-specific perception & production
From Kuhl 2004 Nature Reviews Neuroscience
Near Infrared Spectroscopy (NIRS)
• Based on pulse oximetry
• Measurement of temporal changes in both oxyhemoglobin and deoxyhemoglobin
Principles of NIRS
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
Key research secrets: chin straps, bubbles, ace bandage
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
• 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
• 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
• Very speech like– Preserved segmental consonants and
vowels
• Not like speech at all– Violates continuity and prosody
Comparison to Peña et al.
• State
• Age
• DV
• Path length
• Language
• Stimuli features
ENG ENGENG16 sec 24 sec 32 sec
TON TONTON16 sec 24 sec 32 sec
SCRKOR
SCRKOR
SCRKOR16 sec 24 sec 32 sec
SCRENG
SCRENG
SCRENG16 sec 24 sec 32 sec
KOR KORKOR16 sec 24 sec 32 sec
Infant: continuous
Male infant
Oxy
Total
Female infant
Deoxy
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upper
lower
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upperlower
Infants hearing Scrambled English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upper
lower
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upperlower
Infants hearing Scrambled English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
Infants hearing Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sig
Activation
upper
lower
Infants hearing Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upperlower
Infants hearing Scrambled English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
Infants hearing Scrambled Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upper
lower
Infants hearing Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
Infants hearing Scrambled Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upperlower
Infants hearing Scrambled English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
Infants hearing Tone
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sign
Activation
upper
lower
Infants hearing Tone
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
Infants hearing Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
Infants hearing Scrambled Korean
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
Infants hearing English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of Voxels w/Sig
Activation
upperlower
Infants hearing Scrambled English
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Hemisphere
Number of voxels w/Sig
Activation
upperlower
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• Young infants: most activation to
English+Scrambled Eng compared to other conditions
• Older infants: most activation to straight compared to scrambled and tone conditions
0
0.5
1
1.5
2
2.5
3
3.5
Eng Kor Ton Sc Eng
Sc Kor
Eng Kor Ton Sc Eng
Sc Kor
Ave
rag
e #
of
Vo
xels
Sh
ow
ing
sig
act
iva
tion
Young Infants Old Infants
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Adults hearing Korean
Hemisphere
Number of Voxels w/ Sig
Activation
Adults hearing Tone
Hemisphere
Number of Voxels w/ Sig
Activation
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Adults hearing English
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Adults hearing Scrambled English
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
0
0.5
1
1.5
2
2.5
3
3.5
Left Right
Adults hearing Scrambled Korean
Hemisphere
Number of Voxels w/ Sig
Activation
upperlower
upperlower
upperlower
Adult Results
• LH superiority to English and Korean
• RH superiority to Scrambled conditions
• Bilateral and low activation to Tone
Comparisons between infants and adults
• Language conditions only– Young infants are significantly different from adults– Old infants are not significantly different from
adultsYoung Adults
0
0.5
1
1.5
2
2.5
3
3.5
4
Left Hemisphere Right Hemisphere
English
Korean
0
0.5
1
1.5
2
2.5
3
3.5
4
English
Korean
Left Hemisphere Right Hemisphere
This comparison collapses across straight/scrambled factor
Individual differences
• English (n = 62 infants)– LH Superiority: 71%– RH Superiority: 11%– Equal activation: 2%– No activation: 16%
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• 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!
• John Gore, Chris Cannestraci, and Sohee Park at Vanderbilt University
• Anna Lane for heroic efforts in data analyses!
• McDonnell Foundation and Discovery grants
Asleep Awake
English
Korean
7, 23 old females
KOREAN
Time
-5 0 5 10 15 20 25
% signal change
-4
-2
0
2
4
6
8
AwakeAsleep
ENGLISH
Time
-5 0 5 10 15 20 25
% signal change
-10
-5
0
5
10
15
20
25
30
AwakeAsleep
Sleeping vs Waking Hemodynamic Lines
Asleep Awake
Korean
ScrKorean
Same male, same visit
Korean
Time
-5 0 5 10 15 20 25
% signal change
-10
-8
-6
-4
-2
0
2
4
6
8
AwakeAsleep
Sleeping vs Waking Hemodynamic Lines(same voxel)
SCRAMBLED KOREAN
Time
-5 0 5 10 15 20 25
% signal change
-50
-40
-30
-20
-10
0
10
20
AwakeAsleep
Adult Average
Time
-5 0 5 10 15 20 25-6
-4
-2
0
2
4
6
8
10
12TonalEnglishKorean
Young English and Korean
Time-50510152025% signal change-4-202468101214 EnglishKorean
Average Old English and Korean
Time-50510152025% signal change-6-4-20246EnglishKorean
HemodynamicCurves
Mohinish’s Question
Time
-5 0 5 10 15 20 25
-8
-6
-4
-2
0
2
4
6
8
10
12
Adult probesInfant probes
Principles of NIRS
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
• 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 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
Vibrating Toy Activity
Visual Flicker
Visual CortexMotor Cortex
No Activity
ActivityNo Activity
Stimuli and Design
Individual Results
4-6 mos female 4-6 mos male
7-9 mos female 7-9 mos male
Average Voxels Active
4 to 6 mos 7 to 9 mos adults
Motor Visual Motor Visual Motor Visual
Toy 5 1 5 0 12 5
Video 2 10 0 12 1 12
Characteristics of the BOLD response for different cortical areas
Motor Cortex for Young Group
Time (sec)
-5 0 5 10 15
% signal change
-3
-2
-1
0
1
2
3
4
Motor TaskVisual Task
Motor Cortex for Older Group
Time (sec)
-5 0 5 10 15
% signal change
-4
-3
-2
-1
0
1
2
3
4
Motor TaskVisual Task
Motor Cortex for Adult Group
Time (sec)
-5 0 5 10 15
% signal change
-10
-5
0
5
10
15
20
25
Motor TaskVisual Task
Visual Cortex for Young Group
Time (sec)
-5 0 5 10 15
% signal change
-6
-4
-2
0
2
4
6
8
Motor TaskVisual Task
Visual Cortex for Older Group
Time (sec)
-5 0 5 10 15
% signal change
-6
-4
-2
0
2
4
6
8
Motor TaskVisual Task
Visual Cortex for Adult Group
Time (sec)
-5 0 5 10 15
% signal change
-20
-10
0
10
20
30
40
Motor TaskVisual Task
Mot
orV
isua
l
4-6 mos 7-9 mos Adult
Mean time to peak 13s after stimulus onset
Mean time to peak 6s after stimulus onset
Individual differences
Motor Cortex
Younger Group
% signal change
-10
-5
0
5
10
15
Motor TaskVisual Task
Motor Cortex
Older Group
% signal change
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
Motor TaskVisual Task
Motor Cortex
Adult Group
% signal change
-20
-10
0
10
20
30
40
Motor TaskVisual Task
Visual Cortex
Younger Group
% signal change
-20
-10
0
10
20
30
Motor TaskVisual Task
Visual Cortex
Older Group
% signal change
-15
-10
-5
0
5
10
15
20
Motor TaskVisual Task
Visual Cortex
Adult Group
% signal change
-40
-20
0
20
40
60
80
Motor TaskVisual Task
Mot
orV
isua
l
4-6 mos 7-9 mos Adult
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
• 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