22 THE SCIENTIST | the-scientist.com
NOTEBOOKBehrmann and colleagues have explored
before. “This is consistent with the idea
that when something abnormal—the
epilepsy here, not so much the surgery—
happens early enough, the brain is better
able to reorganize,” Gauthier says, noting
such plasticity is much more difficult for
adult brains.
Behrmann says she and her colleagues
did not have presurgical scans of U. D .’s
brain to compare with postsurgical ones.
However, in subsequent studies of other
patients in which they tracked organi-
zation and activity both before and after
surgery, they found significant differences
in the pre- and postsurgical scans, “so we
know that the surgery has played a role in
bringing about change over and above any
that might have come about presurgically
because of the epilepsy itself,” she says.
“It is really important to understand
how the brain is organized around epi-
leptic tissue and how the brain reorga-
nizes itself after surgery,” says Taylor Abel,
a pediatric neurosurgeon at Children’s
Hospital of Pittsburgh of the University
of Pittsburgh Medical Center. Abel, who
was not involved in the study or treatment
of U.D ., specializes in operating on epilep-
tic patients, and is planning to start work-
ing with Behrmann soon. The results of
the current study are important, he adds,
because if paired with future findings from
patients similar to U.D., they could help
clinicians counsel parents on how their
children will respond to surgery, not only
for epilepsy, but other types of neurologi-
cal disorders, too. —Ashley YeagerTalking Back
In 1995, child psychologists Betty
Hart and Todd Risley reported that
by age three, children in higher-socio-
economic-status households had heard
30 million more words than their counter-
parts in lower-socioeconomic-status
homes. This so-called word gap has
often been invoked to explain why chil-
dren in the former category tend to dis-
play better language skills and perform
better in school compared to those fromunderprivileged homes—with effects that
reverberate throughout their lives.
“Language is implicated in school
achievement, social emotional growth, in
health outcomes [and] in job outcomes
when you’re a grown-up,” says Roberta
Golinkoff, who leads the Child’s Play,
Learning, and Development laboratory at
the University of Delaware. “Language pre-
dicts all these.”
But researchers have struggled to
gain a mechanistic understanding of
this phenomenon. “What people are dis-
covering is that socioeconomic status is
really just a proxy variable,” says Rachel
Romeo, a postdoc in developmental cog-
nitive neuroscience at MIT and Boston
Children’s Hospital. Although factorssuch as household income and parental
education are associated with a child’s
learning abilities, researchers suspect
there are features of the home learning
environment, such as the amount of time
adults spend talking to their children,
that have a more direct influence. But
few studies have been able to measure
these environmental effects on learning
ability, as they are difficult to disentan-
gle from a family’s socioeconomic status,
notes Romeo.
To dig deeper, she and her colleagues
recently set out to determine the neu-
ral underpinnings of language ability
differences across the socioeconomic
spectrum. First, Romeo and her team
measured the language exposure of 40
children between the ages of 4 and 6
from various backgrounds. Each child
carried around an audio recorder for a
single weekend in 2015 or 2016 within
the pocket of a specially designed T-shirt,
a setup that helped capture a child’s
language environment from his or her
perspective. Then, the researchers used
analytical software to count the numberof conversational turns—one turn being
measured as a pair of adult and child
responses separated by five seconds or
less—occurring over every hour for the
48-hour period.
The team conducted the second
part of their study back in the labo-
ratory, where parents and children
who had taken part in the recordings
underwent MRI scans. In their analy-
ses, Romeo and her colleagues specifi-
cally focused on white matter tracts, or
the “information highways” connect-
ing different regions of the participants’
brains, Romeo says. “We were looking
at the strength of these connections in
various parts of the brain.”
The researchers found that tracts
running between regions of the brain
known to be important for language
development in the left hemisphere
had a more coherent structure in chil-
dren who shared greater turn-taking
with their parents. On average, those
children had greater white matter con-
nectivity between Broca’s area and Wer-
nicke’s area, two regions associated with
speech production and comprehension
(J Neurosci, 38:7870–77, 2018).
The results indicate that two-way
adult-child conversation—independent
of the child’s socioeconomic status and
the number of words a child hears—can
strengthen neural pathways involved in
language. “Our research suggests that it’s
not really the volume of language children
hear, but really about the quality of the
conversation—this back-and-forth dia-
logue,” says Romeo.
“This study has added an inter-
esting additional variable that helps
our explanatory power of why [lower
socioeconomic status] might be associ-
ated with poor language outcomes,” says
Rachel Barr, the director of George-
town University’s Early Learning Proj-
ect, who was not involved in this study.
She adds that parents in these families
may have fewer opportunities to share
dialogue with their children—and that
interventions focused on conversational
turn-taking could help. “It’s not just,
‘Add words, and the child’s languageSocioeconomic status is
really just a proxy variable.
—Rachel Romeo
MIT & Boston Children’s Hospital