Maternal support in early childhood predicts larger
hippocampal volumes at school age
Joan L. Luby
, Deanna M. Barch
, Andy Belden
, Michael S. Gaffrey
, Rebecca Tillman
, Casey Babb
, Hideo Suzuki
, and Kelly N. Botteron
Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110;
Department of Psychology, Washington University in St. Louis,
St. Louis, MO 63130; and
Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110
Edited by Marcus E. Raichle, Washington University in St. Louis, St. Louis, MO, and approved January 4, 2012 (received for review November 1, 2011)
Early maternal support has been shown to promote speciﬁc gene
expression, neurogenesis, adaptive stress responses, and larger
hippocampal volumes in developing animals. In humans, a relation-
ship between psychosocial factors in early childhood and later
amygdala volumes based on prospective data has been demon-
strated, providing a key link between early experience and brain
development. Although much retrospective data suggests a link
between early psychosocial factors and hippocampal volumes in
humans, to date there has been no prospective data to inform this
potentially important public health issue. In a longitudinal study of
depressed and healthy preschool children who underwent neuro-
imaging at school age, we investigated whether early maternal
support predicted later hippocampal volumes. Maternal support
observed in early childhood was strongly predictive of hippocam-
pal volume measured at school age. The positive effect of maternal
support on hippocampal volumes was greater in nondepressed
children. These ﬁndings provide prospective evidence in humans of
the positive effect of early supportive parenting on healthy hippo-
campal development, a brain region key to memory and stress
The suggestion that environmental enrichment early in life
results in enhanced brain development was ﬁrst proposed and
investigated by Hebb in the late 1940s and was empirically vali-
dated in rodents 20 y later (1). These ﬁndings provided some of the
ﬁrst quantitative evidence supporting the tangible role of envi-
ronmental experience on structural brain development. More re-
cent research has extended these ﬁndings by investigating the
biological mechanisms by which psychosocial factors inﬂuence
neuronal development. Of critical importance to the study of risk
for psychopathology, animal models have elucidated the mecha-
nisms by which maternal nurturance, a uniquely powerful form
of early enrichment, promotes adaptive programming of the
hypothalamic–pituitary–adrenal axis stress response and hippo-
campal development (2, 3). Improvements in the capacity for
stress modulation have been shown to be related to epigenetic
modiﬁcations whereby methylation of multiple genes results in
changes in gene expression for glucocorticoid and mineralcorti-
coid receptors (4, 5). These changes are associated with increases
in dendritic branching and neurogenesis and related increases in
hippocampal volumes (6–9). Consistent with this phenomenon
and conversely, the stress of early maternal deprivation has been
shown to have negative effects on this cascade (10, 11). A similar
relationship between early nurturance and stress modulation has
also been reported in nonhuman primates (12, 13). This work has
shown that early nurturing in nonhuman animals facilitates the
offspring’s enduring capacity for adaptive stress modulation, a
phenomenon with potentially powerful public health implications
if also operational in humans.
Building on these animal ﬁndings, there has been a surge of
interest in the effects of early experience on brain development
in humans (14). Numerous studies have documented a relation-
ship between key early environmental factors and later cognitive
and socio-emotional outcomes. Studies of Romanian orphans,
using the naturalistic stress of institutional care, have shown that
enhanced early caregiving through placement in therapeutic
foster care had a robust and positive impact on cognitive, social,
and emotional outcomes (15, 16). Differential patterns of DNA
methylation in children raised in institutions compared with
those raised by their biological parents have recently been pro-
vided, suggesting that the epigenetic phenomenon known in
animals might also be operative in human development (17).
Prospective evidence of the impact of early nurturance on
structural brain development has been provided in a few studies
to date. Tottenham et al. (18) reported that institutionalized
orphans who experienced environmental enrichment in the form
of earlier adoption displayed smaller amygdala volumes (an an-
atomical variation associated with better emotion regulation),
but they did not ﬁnd a relationship with hippocampal volumes.
Lupien et al. (19) also reported larger amygdala but no change in
hippocampal volumes in a sample of children exposed since birth
to maternal depression, the latter a condition known to be as-
sociated with decreased parenting sensitivity and responsiveness
(20). In another small study group, larger right amygdala vol-
umes were found in institutionalized children compared with
noninstitutionalized control subjects (21). Additionally, a study
of a small group of premature infants demonstrated that early
environmental enhancement in the neonatal intensive care unit
was associated with positive changes in brain structure, evi-
denced by higher relative anisotropy in several speciﬁcwhite
matter tracts (22). Rao et al. (23) found a relationship between
increased early higher-quality parental care and smaller hippo-
campal volumes in a sample of children exposed to cocaine in
utero, ﬁndings in the opposite direction of that expected from the
animal data. These studies, although suggestive, have not yet
provided ﬁndings in humans analogous to the animal literature
and are limited by the use of populations also exposed to multiple
perinatal and postnatal stressors and traumas known to impact
An increasing body of retrospective data also suggests a re-
lationship between early nurturance, or the lack of nurturance
based on the experience of trauma, and later stress reactivity and
hippocampal volumes in a variety of human populations, in-
cluding those with depression (24, 25). Importantly, numerous
studies have reported that major depressive disorder (MDD) is
associated with smaller hippocampal volumes in adults (26, 27).
The ﬁndings in children and adolescents are less consistent than
in adults, with some investigators reporting no hippocampal
volume differences (28, 29) and others reporting decreased
Author contributions: J.L.L., D.M.B., and K.N.B. designed research; C.B. and T.N.
performed research; R.T. analyzed data; and J.L.L., D.M.B., A.B., M.S.G., C.B., T.N., H.S.,
and K.N.B. wrote the paper.
The authors declare no conﬂict of interest.
This article is a PNAS Direct Submission.
Freely available online through the PNAS open access option.
To whom correspondence should be addressed. E-mail: email@example.com.
February 21, 2012
no. 8 www.pnas.org/cgi/doi/10.1073/pnas.1118003109
volume (30–32). Importantly, numerous developmental studies
have demonstrated that poor-quality parenting (e.g., non-
supportive or harsh) is a risk factor for childhood MDD (33).
Further, a few studies suggest that smaller hippocampal volumes
in adolescents at risk for MDD are associated with increased
susceptibility to the effects of psychosocial stress and subsequent
risk for recurrence or development of MDD (23, 34). A similar
process has also been identiﬁed in a twin sample, in which
smaller hippocampal volumes increased the risk for development
of stress-related psychopathology (35). Taken together, these
ﬁndings suggest intriguing, although potentially complex, rela-
tionships among experiences of early stress, low nurturance,
stress reactivity, and hippocampal volumes in humans, opening
the possibility that the well-characterized phenomena identiﬁed
in animals may also be operative in humans.
Given these converging lines of evidence, one hypothesis is that
impairments in early maternal nurturing contribute to enhanced
and maladaptive stress reactivity, reduced hippocampal volumes,
and increased risk for depression. As described above, there is
some prospective evidence in humans for the effects of maternal
nurturance on structural brain development of the amygdala in
high-risk samples, as well as evidence for nurturance-dependent
alterations in DNA methylation in similar samples. In addition,
retrospective data have established a link between early inter-
ruptions of maternal care, depression, and hippocampal volumes.
However, to date there has been no prospective data documenting
the positive relationship between early maternal nurturance and
structural development of the hippocampus in either typically
developing children or groups at risk for MDD, despite a well-
documented relationship in animals and a putative mechanism of
the developmental psychopathology hypothesis stated above. The
hippocampus is of particular interest given the compelling ﬁndings
on the role of early nurturance and its structural development
from animal studies described above. If a relationship between
early nurturance and hippocampal development is present in
humans, it would ﬁll a key gap in the literature and open the door
to prospective investigation of healthy brain development as well
as mechanisms for the development of depression in certain at-risk
groups as outlined. To address this question, we investigated the
relationship between maternal nurturance objectively measured
through structured observation during the preschool period of
development and later hippocampal volume measured at school
age. These data were derived from a sample of depressed pre-
schoolers and age-matched healthy and “other psychiatric”com-
parison groups, followed prospectively into school age, at which
time neuroimaging was conducted. Examining the relationship
between early maternal nurturance and laterhippocampal volume
in both healthy and depressed children allowed us to secondarily
examine mediators and/or moderators in the relationships be-
tween hippocampal volume, maternal nurturance, and childhood
Subjects were 92 children participating in a longitudinal study of
preschool depression who met all inclusion/exclusion criteria for
magnetic resonance brain imaging at ages 7–13 y. These children
were non–left-hand-dominant children with usable left and/or
right hippocampus T1-weighted MRI volume data, who also had
parent–child interaction data acquired at ages 3–5 y, allowing us
to examine the relationship between early maternal support and
later childhood hippocampal volume. Demographic character-
istics of the study sample divided by depression severity scores
are listed in Tables 1 and 2.
Sex, age, and parental income were examined in separate re-
peated-measures models to determine whether they were sig-
niﬁcantly related to hippocampal volume. Sex was signiﬁcantly
associated with hippocampal volume (P= 0.036), whereas age
(P= 0.955) and parental income (P= 0.088) were not. Therefore,
sex was included as a covariate in subsequent analyses. A repeated-
measures mixed model with compound symmetric covariance
structure was used to model the effects of maternal support, pre-
school depression severity, and their interaction on hippocampal
volume (Table 3). Brain hemisphere (left or right) and sex were
included as covariates in the model. The overall model was sig-
=57.84,P<0.001), with maternal support (F
18.58, P<0.001) and the interaction of maternal support and
preschool depression severity (F
=4.07,P= 0.047) signiﬁcantly
associated with hippocampal volume. The estimated increase in
hippocampal volume by unit of increased maternal support (a
frequency) was 13.4 mm
. A model including the three-way in-
teraction of brain hemisphere, maternal support, and preschool
depression severity was conducted to determine whether the in-
teraction was speciﬁc to one hemisphere (Table 3). The three-way
interaction was not signiﬁcant (F
= 0.04, P= 0.848). Finally,
medication use, internalizing and externalizing symptom severity,
traumatic life events, and maternal history of depression were
added to the model as covariates. After controlling for these var-
iables, maternal support (F
= 18.09, P<0.001) and the in-
teraction of maternal support and preschool depression severity
=5.09,P= 0.027) were still signiﬁcantly associated with
To parse the source of the interaction between maternal
support and preschool depression severity, we dichotomized sub-
jects into those with zero to three preschool depression symp-
toms (severity scores found in healthy samples, therefore a
subgroup with no clinical depression) and those with four to nine
preschool depression symptoms (high severity consistent with
clinical depression) and then examined the relationship of ma-
ternal support and hippocampal volume in these groups. Fig. 1 A
and Bshow the association of maternal support with left and
right hippocampal volume in these groups. Of note, there were
two subjects in the nondepressed group with maternal support
scores considerably greater than the others in this group. To test
whether these subjects were multivariate outliers, the Mahala-
nobis distance (MD) and its probability were calculated for all
nondepressed subjects (36). No subjects had P(MD) <0.001, so
no subjects were considered outliers, and all data were included
in the analyses (notably, even if these subjects are excluded, the
effect of maternal support on hippocampal volume remains
highly signiﬁcant). The relationship between maternal support
and hippocampal volume was signiﬁcant only in low-severity/
nondepressed children (F
= 9.22, P= 0.004) and not in de-
pressed/high-severity children (F
= 2.37, P= 0.134). We then
divided children into four groups (Fig. 2), illustrating that non-
depressed children with high maternal support had signiﬁcantly
larger hippocampal volumes than the following three groups:
nondepressed children with low maternal support (9.2% smaller
volume) and depressed children with high (6.0% smaller vol-
ume) or low maternal support (10.6% smaller volume).
These study ﬁndings provide evidence in humans replicating the
positive relationship between early experiences of maternal nur-
turance and hippocampal volume well demonstrated in animal
models. Using data from a prospective, longitudinal study of de-
pressed preschoolers and comparison groups who underwent
neuroimaging at school age, we found that observationally mea-
sured maternal support during a mildly stressful interactive task in
early childhood was a powerful predictor of larger hippocampal
volume in both hemispheres at school age. The relationship be-
tween maternal support and hippocampal volume remained sig-
niﬁcant even when other variables known to impact hippocampal
volume (e.g., stressful life events, sex, and depression severity)
were included in the model.
Further, maternal support and depression severity interacted
in predicting volume. Positive maternal support was a stronger
Luby et al. PNAS
February 21, 2012
predictor of greater hippocampal volume in nondepressed
children. These ﬁndings suggest that early maternal support
exerts a positive inﬂuence on hippocampal development in
children without depression but not in depressed children, in
whom the negative effects of this risk condition seem to impede
the potential beneﬁts of maternal support. As such, our ﬁndings
did not support the hypothesis that the inﬂuence of maternal
support on hippocampal volume would be found among children
with depression. Instead, these results suggest that either
depression has an effect on hippocampal volumes that is not
mediated by maternal support or that an examination of ma-
ternal support before the onset of depression is needed to ade-
quately test this risk hypothesis. Our sample of depressed
children all had very-early-onset depression that was present
before our assessment of maternal support. Other limitations to
the design include the fact that maternal support was measured
only in early and not later in childhood and that earlier experi-
ences of nurturing before age 3 y, shown to be important to
Table 1. Characteristics of the sample, part 1
severity score 4–9(n=41)
severity score 0–3(n= 51)
Sex 0.46 0.499
Female 56.1 23 49.0 25
Male 43.9 18 51.0 26
Age (y) FE 0.560
6 2.4 1 (1 M, 0 F) 0.0 0 (0 M, 0 F)
7 4.9 2 (0 M, 2 F) 7.8 4 (1 M, 3 F)
8 9.8 4 (1 M, 3 F) 13.7 7 (5 M, 2 F)
9 34.1 14(4M,10F) 39.2 20(9M,11F)
10 24.4 10 (6 M, 4 F) 27.5 14 (10 M, 4 F)
11 19.5 8 (5 M, 3 F) 11.8 6 (1 M, 5 F)
12 4.9 2 (1 M, 1 F) 0.0 0 (0 M, 0 F)
Parental education 2.87 0.412
High school diploma 14.6 6 7.8 4
Some college 41.5 17 33.3 17
4-y college degree 17.1 7 29.4 15
Graduate education 26.8 11 29.4 15
Psychotropic medication use 1.74 0.187
Yes 29.3 12 17.6 9
No 70.7 29 82.4 42
Maternal history of depression 0.80 0.370
Yes 42.5 17 33.3 17
No 57.5 23 66.7 34
Maternal prenatal tobacco use 1.05 0.307
Yes 27.8 10 18.2 8
No 72.2 26 81.8 36
Maternal prenatal alcohol use 4.31 0.038
Yes 36.1 13 15.9 7
No 63.9 23 84.1 37
F, female; FE, Fisher’s exact test; M, male.
Table 2. Characteristics of the sample, part 2
tPMean SD Mean SD
Maternal support 12.17 9.13 12.12 8.91 0.03 0.978
Preschool depression severity 5.12 1.25 1.41 1.04 15.53 <0.001
Internalizing dimensional score 6.66 3.21 3.10 1.97 6.23 <0.001
Externalizing dimensional score 10.12 7.39 4.25 4.38 4.49 <0.001
No. of traumatic life events 2.78 1.76 1.57 1.37 3.67 <0.001
IQ score 104.1 14.1 108.2 15.9 1.30 0.197
Birth weight (kg) 3.24 0.55 3.34 0.63 0.86 0.392
Gestational age (wk) 38.82 2.09 39.06 2.38 0.50 0.620
Days in NICU 0.31 0.98 3.50 14.92 1.35 0.185
Hippocampus volume, right (mm
) 1,720 169 1,789 212 1.66 0.101
Hippocampus volume, left (mm
) 1,715 136 1,781 195 1.79 0.078
IQ, intelligence quotient; NICU, neonatal intensive care unit.
www.pnas.org/cgi/doi/10.1073/pnas.1118003109 Luby et al.
developmental outcomes, were not prospectively studied. Pro-
spective research in high-risk samples before the onset of de-
pression may be needed to speciﬁcally assess whether hippocampal
volume mediates a relationship between poor early nurturance and
subsequent risk for depression.
The experience of a nurturing caregiver early in life has proven
to be one of the most essential prerequisites for healthy de-
velopment and adaptive functioning in mammals (37). The cur-
rent data provide evidence that the well-established signiﬁcant
impact of positive parenting on enhancing and maintaining
hippocampal neuroplasticity, likely through epigenetic mecha-
nisms enhancing neurogenesis, as suggested by the work of
Naumova et al. (17), may also to be operative in humans. Fur-
ther, it was notable that this effect remained robust even after
controlling for other factors known to impact hippocampal vol-
ume, such as stressful life events and maternal history of de-
pression. Importantly, although 96.7% of caregivers in this study
sample were mothers, we expect that this effect pertains to the
primary caregiver (the provider of nurturance) whether it be
mother, father, grandparent, or other.
Whether maternal support early in childhood is more or less
powerful than at later periods of development is of interest and
remains unclear from these data. However, sensitive periods for
the importance of maternal support have been suggested by early
adoption studies (15). However, given the central role of the
caregiver in the life of the young child, this developmental period
would seem to be an optimal time for enhancing the early ma-
ternal–child relationship. On the basis of these data, one cannot
rule out that the relationship between maternal support and
hippocampal volume in offspring is based on genetic factors, that
supportive caregivers could have larger hippocampal volumes
and then have biological children with larger volumes. However,
there is no evidence in the literature of a relationship between
hippocampal volume and supportive care giving in adults. The
Fig. 1. (A) Left side hippocampal volume by preschool depression severity and maternal support. (B) Right side hippocampal volume by preschool depression
severity and maternal support.
Table 3. Repeated-measures mixed models of hippocampal volume
Model Estimate Fdf P
Left brain hemisphere −3.20 0.06 1, 75 0.811
Female sex −78.87 5.76 1, 87 0.019
Preschool depression severity 7.68 0.39 1, 87 0.533
Maternal support 13.38 18.58 1, 87 <0.001
Preschool depression severity ×maternal support −1.59 4.07 1, 87 0.047
Left brain hemisphere −5.40 0.09 1, 74 0.761
Female sex −78.82 5.75 1, 87 0.019
Preschool depression severity 7.63 0.39 1, 87 0.536
Maternal support 13.37 18.55 1, 87 <0.001
Preschool depression severity ×maternal support −1.61 4.02 1, 87 0.048
Preschool depression severity ×maternal support ×left brain hemisphere 0.06 0.04 1, 74 0.848
Left brain hemisphere 0.74 0.00 1, 74 0.954
Female sex −75.57 4.62 1, 80 0.035
Psychiatric medication use −49.08 1.26 1, 80 0.265
Internalizing dimensional score 11.24 1.87 1, 80 0.175
Externalizing dimensional score −4.01 1.42 1, 80 0.237
Number of traumatic life events −11.17 0.86 1, 80 0.357
Maternal history of depression 28.95 0.59 1, 80 0.446
Preschool depression severity 11.30 0.44 1, 80 0.511
Maternal support 14.25 18.09 1, 80 <0.001
Preschool depression severity ×maternal support −1.92 5.09 1, 80 0.027
Luby et al. PNAS
February 21, 2012
available data also suggest that heritability of hippocampal vol-
umes is moderate and lower than many other brain regions (38).
Furthermore, numerous studies have demonstrated that the
hippocampus is sensitive to environmental and psychosocial
inﬂuences in both animals and humans, making a purely genetic
mechanism less likely (9, 39). Despite these assurances, longi-
tudinal scan data, including scans at the preschool period, would
be necessary to clarify the role of genetic factors, a conclusion
underscored by previous research showing that smaller hippo-
campal volumes increased the risk for development of stress-
related psychopathology, suggesting that complex interactive
processes could be at play (35).
These data extend the current literature, establishing the cru-
cial role of the caregiver in early childhood for healthy social and
emotional development by demonstrating that the early experi-
ence of supportive caregiving also positively impacts structural
development of the hippocampus, at least in children without
early-onset depression. Notably, the relationships between ma-
ternal support and hippocampal volumes remained highly sig-
niﬁcant when comorbid internalizing and externalizing symptoms
were controlled in the analysis. The importance of this effect is
underscored by the fact that the hippocampus is a brain region
central to memory, emotion regulation, and stress modulation, all
areas key to healthy social adaptation. We believe these ﬁndings
have potentially profound public health implications and suggest
that greater public health emphasis on early parenting could
be a very fruitful social investment. The ﬁnding that early par-
enting support, a modiﬁable psychosocial factor, is directly re-
lated to healthy development of a key brain region known to
impact cognitive functioning and emotion regulation opens an
exciting opportunity to impact the development of children in
a powerful and positive fashion. This ﬁnding, when replicated,
would strongly suggest enhancement of public policies and pro-
grams that provide support and parenting education to caregivers
early in development.
Materials and Methods
Participants. The study sample was originally recruited between the ages of 3
and 6 y from daycare centers and preschools in the St. Louis metropolitan area
using a screening checklist to oversample children with symptoms of de-
pression (40). Healthy preschoolers and those with other psychiatric dis-
orders were included as comparison groups for the original study sample
ascertainment. Preschoolers with neurological or chronic medical problems
or those with signiﬁcant developmental delays were excluded. Informed
consent (or assent) was obtained from all study subjects, who were fully
informed about the nature and consequences of the study procedures be-
fore participation. Children and their caregivers were assessed at four to six
annual waves before the time of scanning.
Measures. At each annual wave, parents were interviewed about their child
using the Preschool Age Psychiatric Assessment (PAPA), an age-appropriate
diagnostic interview addressing the child’s psychiatric symptoms and stressful
life events with established reliability (41). The PAPA was used to derive
depression severity scores by summing all symptoms of depression, a variable
previously shown to be a sensitive measure of the severity of illness (42).
Further details on training and administration of the PAPA in the study
sample can be found in Luby et al. (40).
At the second annual wave, when subjects were between the ages of
4 and 7 y, parent and child were also observed interacting in a mildly
stressful challenging task in the laboratory, “the waiting task,”during
which maternal support was measured. The waiting task is a parent–child
interaction paradigm designed to elicit mild stress for both members of
thedyad(43).Thetaskrequiresthechild to wait for 8 min before opening
a brightly wrapped gift, which is sitting within arm’s reach. Concurrently
the child’s primary caregiver completes questionnaires. The supportive
and/or nonsupportive care giving strategies that the parent uses to help
regulate the child’s impulse and desire to open the gift immediately are
coded by staff trained to reliability. Each display of speciﬁctypesofsup-
portive strategies by the caregiver is counted as 1 unit. Several research
groups have previously reported acceptable psychometric properties for
the task, and it is a well-validated approach to measuring parenting
strategy during which maternal support and responsiveness was evalu-
ated (43, 44).
Maternal history of depression was measured using the Family Interview
for Genetic Studies (45), a widely used and well-validated measure of family
history of psychiatric disorders. Detailed methods of training and adminis-
tration are described by Luby et al. (40).
Structural Imaging Methods. Parents of either healthy or depressed study
subjects who were participants in a longitudinal study of preschool-onset
depression were screened by phone to determine whether any exclusion
criteria for MRI scanning were present. Exclusion criteria included (i) con-
traindications for MRI scanning; (ii ) head injury with loss of consciousness >5
min; (iii) stroke, seizure disorder, or other chronic neurological or medical
illness with known neurological impact; (iv) diagnosis of a pervasive de-
velopmental disorder; and (v) treatment for lead poisoning.
All MR scans were performed on a Siemens 3.0-T Tim Trio dedicated
research scanner. Subjects were scanned without sedation in a semi-
standardized position. Two 3D T1-weighted magnetization prepared rapid
gradient echo research-tailored MR scans (1-mm isotropic voxels) were ac-
quired sagittally (repetition time 2,400 ms, echo time 3.16 ms, inversion
time 1,200 ms, ﬂip angle 8°, slab 160 mm, 160 partitions, 256 ×256 matrix,
ﬁeld of view 256, total scanning time 12:36). Images were coregistered and
averaged to increase signal to noise ratio (46), then 16-bit image data were
linearly interpolated to 0.5-mm
voxels and converted to 8-bit using AN-
Hippocampal volumes were derived from a well-established template-
based automated segmentation using high-dimensional transformation
methods (48–50). Brieﬂy, hippocampal segmentations and volumes were
derived from an atlas- or template-based automated segmentation using
a high-dimensional transformation after placement of standardized land-
marks by an experienced rater (C.B.) (51) and preliminary transformations
using these landmarks. Hippocampus boundary deﬁnitions were standard-
ized as detailed in previous reports (48, 52). As speciﬁed by these deﬁnitions,
a template segmentation was created by hand (C.B.) and based on one
subject with typical anatomy and reviewed by neuroanatomical gold stan-
dard experts (K.N.B. and Mohktar Gado). This gold standard hippocampal
segmentation was converted to a 3D tessellated surface. Using the land-
marks, the target (subject) images were oriented to the template image by
initially applying a rigid landmark transformation algorithm, followed by
a more precise target to template nonlinear, large deformation landmark
matching algorithm (LDL). Voxel intensities in each target image were scaled
to more closely match those of the template image. A high-dimensional
transformation, large deformation diffeomorphic metric mapping (51), was
then used to generate a transformed template surface. After inverting the
LDL algorithm described above, the transformed template surface repre-
sented the target (subject) hippocampus. The reliability of this process is
equivalent or superior to manual outlining by experts (52). All segmentation
results were blindly reviewed for accuracy (C.B.), and inadequately deﬁned
hippocampi were not included in analyses. Hippocampal volumes included
all hippocampal gray matter and white matter contained within the
ACKNOWLEDGMENTS. The authors thank Michael J. Miller and Tilak
Ratnanather of the Center for Imaging Science, The Johns Hopkins University,
for their technical assistance and insights with the implementation of the
large deformation diffeomorphic metric mapping to quantify the hippo-
Fig. 2. Hippocampus volume by preschool depression severity and maternal
www.pnas.org/cgi/doi/10.1073/pnas.1118003109 Luby et al.
campus volumes. Funding for this study was provided by National Institute of
Mental Health Grants MH64769 (to J.L.L.) and MH090786 (to J.L.L., D.M.B.,
and K.N.B.). The data reported in this paper are archived at the Washington
University School of Medicine.
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