Functional
Neuroimaging of
Speech Perception
in Infants
Dehaene-Lambertz, G. ,
Dehaene S., and Hertz-Pannier,
L.
By Divya Patel
Why study infants?
• Adult human brain: anatomical and
functional specialization for speech
processing
• How?
– clarify how it emerges through
development
Language and infants?
• Considerable language takes place in the
1st year
• Development in:
– Phonology: organization of sounds
– Prosody: tone of voice, rhythm
– Word segmentation: when a word
starts/ends
Motivation
• Not much known about brain mechanisms
• Studies mostly use ERPs
– Great  know temporal lobes contain
neural circuit for phoneme
discrimination
– Not as great  do not provide spatial
information
• This study uses fMRI
Experimental Design
20 healthy, non-sedated infants (2-3mo)
Speech = highly intonated female voice; in French
20s of forward
speech
20s of backward
speech
20s Silence
20s Silence
Hypothesis
• Forward speech = ↑ activation than
backward speech
• Fast temporal auditory transitions and
phonetic information will be jointly
activated
Activation to Sound
• Similar to adults
Brain Lateralization
• Similar to
adults
Forward Speech vs.
Backward Speech
• In adults, the
area is left
superior
temporal
sulcus
Awake vs. Asleep
Was the hypothesis
supported?
• Forward speech = ↑ activation than
backward speech in left angular gyrus and
left mesial parietal lobe
Yes
• Fast temporal auditory transitions and
phonetic information will be jointly
activated in left temporal lobe
– From superior temporal gyrus to
surrounding areas of superior temporal
sulcus
Other underlying
mechanisms?
• In adults:
– Precuneus and dorsolateral PFC (dlPFC)
activated during retrieval
Yes,
there
seems
to
be
• In infants:
– Precuneus and dlPFC activated
• May indicate early engagement of
active memory retrieval mechanism
Strengths
Limitations
• Approaches were
different than prior
studies
• Not enough
background
– Used fMRI
– Used non-sedated
babies
• Very straight forward
• Images corresponding
to brain parts
– Assumed all
readers would
know basic infant
brain
development
Future Directions
• It would be interesting to do a longitudinal
study, to understand when exactly the
changes take place
• To create a study where retrieval can be
tested, perhaps through habituation
• To find specific evidence for either
– nativist view (language mechanisms are
innate)
– interactionist view (language
mechanisms are developed through
interaction)
QUESTIONS?
Dehaene-Lambertz G, Dehaene S, Hertz-Pannier L.
(2002) Functional neuroimaging of speech perception
in infants. Science 298(5600):2013-5.