this area is undergoing changes during infan-
cy and has not yet acquired its full compe-
tence for the native language by 3 months.
However, we found a significant advantage
for the native language in the left angular
gyrus, the left precuneus, and, in awake ba-
bies only, the right prefrontal cortex. In
adults, the left angular gyrus shows greater
activation when subjects hear words than
when they hear nonwords (4, 5) or when they
hear sentences in a known language relative
to hearing sentences in an unknown language
or backward speech (1–3). Moreover, the pre-
cuneus and DLPFC are activated, often with
a right lateralization, when adults retrieve
verbal information from memory (22–24).
Activation of both regions in 3-month-olds
may indicate the early engagement of active
memory retrieval mechanisms. This would fit
with behavioral evidence that infants of that
age have already memorized the prosodic
contours of their native language (17, 19),
although they may not remember single
words until the age of 7 months (6).
Two mechanisms of language acquisition
are classically opposed. According to one view,
the human brain is equipped with genetically
determined mechanisms of language processing
that endow the infant with an early linguistic
competence without which language acquisi-
tion would be impossible (25). For others, the
infant brain is initially immature and plastic,
and exposure to speech inputs progressively
shapes its organization through domain-general
mechanisms of learning and plasticity (26).
Without resolving this debate, our results pro-
vide evidence that should be accommodated by
any model of language development. First, the
areas activated by the native language are not
confined to primary auditory cortices, even dur-
ing the first few months of life. Second, neither
do they extend widely into other cortical terri-
tories such as the visual areas; rather, they
remain confined to regions that are similar to
those observed in adults in both their localiza-
tion and their lateralization. Third, frontal cor-
tex already exhibits functional specificity in
infants and thus can no longer be assumed to be
silent in the first months of life. The delayed
synaptogenesis and myelination of this area,
and its immature level of metabolic activity,
need not imply that it does not contribute to
early cognitive processes (27). Overall, the pre-
frontal activation, in coordination with a left-
lateralized temporoparietal activation partially
similar to that found in adults, favors a descrip-
tion of language acquisition as a progressive
differentiation of a preconstrained network of
left-hemispheric regions under the influence of
active mechanisms of attention and effort (28).
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S. Margules, C. Pallier, J. B. Poline, and D. Rivie`re for
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Institut Fe´de´ratif de Recherches 49, Hoˆpital Neck-
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Supporting Online Material
Materials and Methods
6 August 2002; accepted 21 October 2002
Fig. 3. Interaction between wakefulness and the linguistic nature of the stimuli (voxel P ⬍ 0.01,
cluster P ⬍ 0.05, corrected). This comparison isolated a right dorsolateral prefrontal region that
showed greater activation by forward speech than by backward speech in awake infants, but not
in sleeping infants.
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