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Abstract:
How do human
cultural
inventions
such as reading
result
in neural
re-organization?
In this first longitudinal
study
with young
completely
illiterate
adult
participants,
we measured
brain
responses
to speech,
text, and other
categories
of visual
stimuli
with fMRI
before
and after a group
of
illiterate
participants
in India
completed
a literacy
training
program
in which
they learned
to read and write
Devanagari
script.
A literate
and an illiterate
no-training
control
group
were
matched
to the
training
group
in terms
of socioeconomic
background
and were
recruited
from
the same
societal
community
in two villages
of a
rural area near Lucknow,
India.
This design
permitted
investigating
effects
of literacy
cross-sectionally
across
groups
before
training
(N=86)
as well as longitudinally
(training
group
N=25).
The two
analysis
approaches
yielded
converging
results:
Literacy
was
associated
with enhanced,
left-lateralized
responses
to written
text
along
the ventral
stream
(including
lingual
gyrus,
fusiform
gyrus,
and parahippocampal
gyrus),
dorsal
stream
(intraparietal
sulcus),
and (pre-)
motor
systems
(pre-central
sulcus,
supplementary
motor
area)
and thalamus
(pulvinar).
Significantly
reduced
responses
were observed
bilaterally
in the superior
parietal
lobe (precuneus)
and in the right angular
gyrus.
These
effects
corroborate
and extend
previous
findings
from
cross-sectional
studies.
However,
effects
of literacy
were
specific
to written
text and (to a lesser
extent)
to
false fonts.
We did not find any evidence
for effects
of literacy
on
responses
in the auditory
cortex
in our Hindi-speaking
participants.
This
raises
questions
about
the extent
to which
phonological
representations are altered by literacy acquisition.
