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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. 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

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  1. An optical imaging study on language recognition in the first year of life Susan Hespos Northwestern University

  2. 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?

  3. 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

  4. 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

  5. From Kuhl 2004 Nature Reviews Neuroscience

  6. Near Infrared Spectroscopy (NIRS) • Based on pulse oximetry • Measurement of temporal changes in both oxyhemoglobin and deoxyhemoglobin

  7. Principles of NIRS

  8. 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

  9. Key research secrets: chin straps, bubbles, ace bandage

  10. 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

  11. 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)?

  12. 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)

  13. Scrambled Conditions • Very speech like • Preserved segmental consonants and vowels • Not like speech at all • Violates continuity and prosody

  14. Comparison to Peña et al. • State • Age • DV • Path length • Language • Stimuli features

  15. 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

  16. Infant: continuous

  17. Male infant Female infant Oxy Total Deoxy

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. 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

  27. 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

  28. Infant Results • LH superiority across all language conditions • Optical imaging can detect differences in auditory cortex • Across conditions • Between hemispheres • Between groups of channels

  29. 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

  30. 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

  31. Adult Results • LH superiority to English and Korean • RH superiority to Scrambled conditions • Bilateral and low activation to Tone

  32. 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

  33. Individual differences • English (n = 62 infants) • LH Superiority: 71% • RH Superiority: 11% • Equal activation: 2% • No activation: 16%

  34. 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

  35. 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)

  36. Thanks! • John Gore, Chris Cannestraci, and Sohee Park at Vanderbilt University • Anna Lane for heroic efforts in data analyses! • McDonnell Foundation and Discovery grants

  37. 7, 23 old females Awake Asleep English Korean

  38. Sleeping vs Waking Hemodynamic Lines

  39. Same male, same visit Awake Asleep Korean Scr Korean

  40. Sleeping vs Waking Hemodynamic Lines (same voxel)

  41. 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

  42. 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

  43. Principles of NIRS

  44. 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

  45. 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

  46. 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

  47. Stimuli and Design Motor Cortex Visual Cortex Activity No Activity Vibrating Toy Activity No Activity Visual Flicker

  48. Individual Results 4-6 mos female 4-6 mos male 7-9 mos female 7-9 mos male

  49. Average Voxels Active

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