Viral infection during pregnancy is correlated with increased frequency of
neurodevelopmental disorders. This phenomenon has been studied in mice prenatally
subjected to maternal immune activation (MIA). We previously showed that maternal
T
helper 17 (Th17) cells promote the development of cortical and behavioral abnormalities
in MIA-affected offspring. Here, we show that cortical abnormalities are preferentially
localized to a region encompassing the dysgranular zone of the primary somatosensory
cortex (S1DZ). Moreover, activation of pyramidal neurons in this cortical region was
sufficient to induce MIA-associated behavioral phenotypes in wild-type animals, while
reduction in neural activity rescued the behavioral abnormalities in MIA-affected
offspring. Furthermore, sociability and repetitive behavioral phenotypes could be
selectively modulated according to the efferent targets of S1DZ. Our work identifies
a
cortical region primarily, if not exclusively, centered on the S1DZ as the major node
of
a neural network that mediates behavioral abnormalities observed in offspring exposed
to
maternal inflammation.
In humans, viral infection during pregnancy has been correlated with increased
frequency of neurodevelopmental disorders in offspring
1–6
.
This phenomenon has been modeled in mice
7–10
. We previously
reported that the offspring from pregnant dams injected with polyinosinic:polycytidylic
acid (poly(I:C)), which mimics viral infection, on embryonic day 12.5 (E12.5) exhibit
behavioral abnormalities including abnormal communication, increased repetitive
behaviors, and deficits in sociability
11
. In parallel to the behavioral abnormalities, we also observed that
MIA-affected offspring display patches of disorganized cortical cytoarchitecture during
embryonic development as well as in adulthood. The cortical phenotype was manifested
as
a loss of the cortical layer-specific markers special AT-rich sequence-binding protein
2
(SATB2) and T-brain-1 (TBR1)
11
.
Development of both MIA-associated behavioral phenotypes (MIA behaviors) and cortical
patches were prevented by knocking out a key transcriptional regulator of Th17 cells,
retinoic acid receptor-related orphan nuclear receptor gamma t (RORγt), in
maternal T-cells, or by inhibiting the activity of their effector cytokine IL-17a
in
pregnant dams
11
. These observations
suggested that the maternal Th17 cell/IL-17a pathway is crucial for inducing MIA
behaviors and for generating cortical patches in the offspring. However, whether the
cortical phenotype is the underlying cause of the behavioral abnormalities in MIA
offspring remained undetermined.
Characterization of cortical patches
We first wished to determine the distribution of cortical patches in the
brains of adult MIA offspring by matching the locations of cortical regions that
lack expression of SATB2 or TBR1 to those in a reference mouse brain atlas (Fig. 1a)
12
. Cortical patches found in individual animals often
retained similar mediolateral (ML) and dorsoventral (DV) coordinates through serial
coronal sections, suggesting that many form a single continuous patch extending
along the AP axis, rather than forming a series of independent patches (Extended Data
Fig. 1a). Although cortical patches
were detected at multiple locations throughout the cortex, they were prevalently
observed in the primary somatosensory cortex (S1) at the anteroposterior (AP) level
~0.5 mm posterior to the Bregma (AP=−0.5 mm) (90 %
of animals, N=10) (Fig. 1b and Extended Data Fig. 1), as well as in the
secondary motor cortex (M2) and other cortical regions, including the temporal
association area (TeA) (80% and 40% of animals, respectively,
N=10) (Fig 1b and Extended Data Fig. 1). Cortical patches were also most
predominantly present in S1 with respect to both their number and sizes (Extended
Data Fig. 1d), and often present in S1
unilaterally (60% of animals, N=10). Furthermore, registration of
cortical patches in individual MIA animals onto the same reference plane near
~AP −0.5mm revealed that the cortical patches most consistently
centered on S1DZ, a region of the primary somatosensory cortex that is
morphologically characterized by the absence of a discernible 4th cortical layer and
implicated in muscle- and joint-related functions (56% of animals,
N=50) (Fig. 1c, and Extended Data Fig. 2)
13–15
. Based on
these results, we decided to carry out further analysis on S1 patches near
~AP−0.5 mm.
Deficits in interneuron function or dys-regulation of neural activity in the
somatosensory pathway have been previously associated with both genetic and
environmental mouse models of neurodevelopmental disorders
16–18
. On a similar note, we found that S1 cortical patches of MIA
offspring display a specific loss of PV expression, which marks a class of
interneurons derived from the medial ganglionic eminence
19
. This deficit in PV expression could reflect
either the loss of PV protein expression or the loss of neurons marked by PV. We
observed no significant differences in the expression of the neuron-specific marker
NeuN
20
or of the
vasoactive intestinal polypeptide (VIP)
19
which is expressed in interneurons derived from the caudal
ganglionic eminence, between PBS control and MIA offspring (Fig. 1d, e, and Extended
Data Fig. 3a,b). To test whether the decrease in the number of
PV+ neurons results in a diminished inhibitory drive onto S1
pyramidal neurons, we used whole-cell patch clamp recordings to measure the
miniature Inhibitory Post-Synaptic Currents (mIPSCs) in S1 pyramidal neurons of PBS
or MIA offspring. We indeed observed a reduction in frequency, but not amplitude,
of
mIPSC (Extended Data Fig. 3c–h)
paralleled by an increase in the number of S1 neurons that express c-Fos, a marker
of neuronal activation (Fig. 1f, g and Extended Data Fig. 3i, j).
Cortical patches are predictive of MIA behaviors
In order to determine whether the development of MIA-associated behaviors and
the appearance of cortical patches depend on the developmental timing at which MIA
is induced, we injected poly(I:C) into pregnant dams at embryonic stages E12.5,
E15.5, or E18.5, and assessed their offspring for MIA-associated behavioral
phenotypes. We first examined the offspring’s ability to communicate by
measuring the ultrasonic vocalization (USV) made by pups upon separation from their
mothers at postnatal day 9 (P9). As previously reported
11
, pups from pregnant dams injected with
poly(I:C) at E12.5 (MIA offspring) emitted more USV calls than pups from
PBS-injected dams (PBS offspring). However, such an increase was not observed in the
offspring from dams injected with poly(I:C) either at E15.5 or E18.5 (Extended Data
Fig. 4d–g). We also examined
repetitive behaviors using the marble-burying assay, natural inclination towards
social targets with the sociability assay as well as anxiety-related behaviors by
measuring the time spent by adult MIA offspring at the center of an open field
(Extended Data Fig. 4a–c). For all
behaviors, we observed deficits in the offspring when exposed to prenatal MIA at
E12.5. Again, the offspring’s behaviors from mothers injected with poly(I:C)
either at E15.5 or E18.5 were indistinguishable from those from PBS-injected mothers
(Extended Data Fig. 4h–n), except
for a reduction observed in the center time during the open field assay for
offspring exposed to MIA at E15.5. Importantly, chamber preference during
habituation and the total interaction time during the sociability assay and the
total distance traveled during the sociability and open field assays were similar
between the different treatment groups suggesting that differences in activity or
arousal levels cannot explain the observed behavioral differences (Extended Data Fig.
4i, k, l, n). Our data strongly
indicate that all behavioral abnormalities emerge from a discrete developmental
stage, allowing us to examine whether the presence of cortical patches is predictive
of MIA behavioral phenotypes. Indeed we observed cortical patches in the S1 in
79% of offspring from dams injected with poly(I:C), but not PBS, at E12.5.
Yet, cortical patches were seen only in 13% or none of the offspring when
poly(I:C) was administered at E15.5 or E18.5, respectively (Fig. 2a). Thus, maternal-inflammation
induced at E15.5 and
E18.5, unlike at E12.5, was ineffective in generating cortical patches and also
failed to produce behavioral abnormalities in MIA offspring. Furthermore, the size
of the S1 cortical patches correlated with the severity of behavioral phenotypes:
the cortical patch sizes ranged between 0 (absence of the cortical patch) and 1
mm2 and were positively correlated with the marble burying index,
while negatively correlated with both sociability and time spent in the center of
an
open field (Fig. 2b–d). The total
distance traveled during the sociability assay was not affected by patch size (Fig.
2e). The size of cortical patches found
outside of S1 also did not correlate with the severity of behavioral abnormalities
(Extended Data Fig. 4o–q).
The accompanying paper by Kim et al. demonstrates that a single species of
bacteria – segmented filamentous bacteria (SFB) – present in C57BL/6
animals bred by Taconic Biosciences, but not in those from Jackson Laboratory, is
required in mothers to induce behavioral abnormalities in MIA offspring (Kim et al.,
accompanying paper). All animals used in this study were also from mouse colonies
carrying SFB. In accordance with our observation above, we found that the size of
cortical patches in MIA offspring from SFB-present (SFB+) dams
was highly correlated with the severity of the offspring’s behavioral
phenotypes, but not with the total distance traveled during the behavioral assay
(Fig. 2f–i). On the other hand,
offspring from SFB-absent (SFB−), MIA-exposed mothers did not
exhibit S1 cortical patches.
Lastly, we previously showed that recombinant IL-17a injected into the
ventricles of the developing brain requires intact IL-17a receptor subunit A
(IL-17Ra) expression in the fetus to induce MIA-associated phenotypes
11
. We also previously noted that
IL-17Ra expression is upregulated in the cortical plate upon MIA. This induction is
mostly restricted to ankyrin-3 (Ank3)+ and
NeuN+ postmitotic neurons, but not paired box 6
(Pax6)+ neuronal progenitors (Extended Data Fig. 5a)
20–22
. In line
with this observation, knocking-out IL-17Ra in offspring using a Cre driver line
specific for the nervous system – Nestin-Cre
23
– prevented the development of S1
cortical patches and the associated phenotypes; loss of SATB2 and PV expression or
increase in the number of c-Fos+ neurons was not observed in
these animals. As expected, brain-specific abrogation of IL-17Ra in offspring also
rescued MIA-induced behavioral abnormalities (Extended
Data Fig. 5b–j). Together, these data collectively show that the
presence of cortical patches is highly predictive of MIA-induced behaviors. They
further suggest that timing of inflammation, composition of maternal gut bacteria
as
well as IL-17Ra expression in the fetal brain dictate the severity of MIA-induced
behavioral phenotypes in the offspring by contributing to the formation of S1
cortical patches.
Increasing neural activity in the S1DZ region drives MIA behaviors
Our characterization of cortical patches indicated that an increase in the
overall neural activity within S1 could be a major factor driving abnormal
behavioral phenotypes in MIA offspring (Fig. 1f,
g and Extended Data Fig.
3c–j). Indeed, previous studies suggested that deficits in
interneuron development and subsequent perturbations of excitation/inhibition (E/I)
balance could be the underlying cause(s) of neurodevelopmental disorders
24–33
. We thus asked if increasing neural activity in S1 could
recapitulate MIA-induced behaviors in WT adult animals. We virally expressed either
Enhanced Yellow Fluorescent Protein (EYFP), channelrhodopsin (ChR2)
34
, or halorhodopsin (NpHR)
35
using the neuron-specific
promoter, human Synapsin 1 (hSyn1) (Fig. 3c
and Extended Data Fig. 6a). Both the virus and
the optical fibers were bilaterally targeted to a region centered on S1DZ (S1DZ
region), where cortical patches were most consistently observed in MIA animals
(Fig. 3a). Animals were subsequently
subjected to the behavioral assays described above, while receiving optical
stimulation at 3-minutes intervals (a 3 minute-‘On’ session followed
by a 3 minute-‘Off’ session or vice versa) (Fig. 3b). Increasing neural activity with
ChR2 in
wild-type (WT) offspring resulted in enhanced marble burying behaviors, impaired
sociability without any effects on total interaction time, and reduced time spent
at
the center of an open field (Fig. 3d–h
and Extended Data Fig. 6). On the other hand,
photostimulation of EYFP-expressing neurons in the control group failed to induce
any MIA-associated behaviors. Furthermore, reducing neural activity in S1 using NpHR
did not generate behavioral abnormalities, with the exception of a slight, yet
significant, increase in marble burying behavior compared to the EYFP-expressing
control group (Fig. 3e). This effect is likely
due to non-specific inhibition of different types of neurons in the photostimulated
region. Therefore, to specifically isolate the contribution of only excitatory
glutamatergic neurons, we used a Cre-dependent strategy to express opsins under the
control of the vesicular Glutamate Transporter 2 promoter (vGluT2) (Fig. 3i)
36
. Increasing activity of vGluT2+ neurons
using ChR2 recapitulated all three MIA-associated behaviors, while photostimulation
in NpHR- or EYFP-expressing animals failed to induce these behavioral abnormalities
(Fig 3j–n and Extended Data Fig. 7a–f). We also selectively modulated
neural activity in PV+ neurons by virally driving Cre-dependent
opsin expression in PV-Cre animals (Fig.
3o)
37
. Inhibiting
the activity of the PV+ neuronal population with NpHR mimicked
the decrease in the number of PV+ neurons observed in the
MIA-cortical patches and recapitulated all three MIA-associated behavioral
phenotypes (Fig. 3p–t and Extended Data Fig. 7g–l). On the other
hand, photostimulation of EYFP- or ChR2-expressing animals did not produce any
observable deficits (Fig. 3q–t).
We next examined whether the ability to drive these MIA behaviors is a
general feature of S1 or is specific to the S1DZ region
(~AP=−0.5), where we predominantly observed cortical
patches. We targeted ChR2 and optical implants into four additional anterior and
posterior regions of S1, while keeping the ML coordinates consistent (Extended Data
Fig. 8a–c).
Photostimulation of these off-target regions did not elicit MIA phenotypes in the
marble burying or sociability assays (Extended Data
Fig. 8d–f). The same manipulation carried out medially in the
forelimb region (S1FL) or laterally in the barrel field of primary somatosensory
cortex (S1BF) also failed to induce any behavioral abnormalities (Extended Data Fig.
8g–l). Lastly, since
cortical patches are often observed only in one hemisphere (Extended Data Fig. 1),
we asked if unilateral manipulation
of neural activity in the S1DZ region is sufficient to produce MIA behavioral
phenotypes. Targeting ChR2 and optical implants to either hemisphere unilaterally
increased the number of c-Fos+ neurons both in ipsilateral as
well as contralateral S1 and was capable of driving MIA behaviors similarly to the
bilateral stimulation (Extended Data Fig. 9).
Taken together, these results demonstrate that MIA-like behaviors can be
recapitulated in WT animals either through the activation of excitatory neurons or
the inhibition of PV+ inhibitory neurons and that this feature is
primarily localized to the cortical region centered on the S1DZ.
Reducing neural activity in the S1DZ region rescues MIA behaviors
We next asked whether reduction of neural activity in the S1DZ region of MIA
offspring is sufficient to correct the observed behavioral abnormalities.
Photostimulation of NpHR-expressing animals decreased the number of
c-Fos+ cortical neurons when compared to those in
photostimulated EYFP-expressing MIA animals (Fig.
4a,b and Extended Data Fig. 10a).
This inhibition of neural activity was sufficient to suppress enhanced marble
burying, restore sociability, and increase the time spent in the center of the open
field to levels observed in control PBS animals (Fig.
4c–f and Extended Data Fig.
10). Photostimulation of EYFP- or ChR2-expressing animals did not rescue
any behavioral deficits (Fig. 4c–f).
Thus, the foregoing data demonstrate that acute reduction in neural activity in the
S1DZ region is sufficient to rescue behavioral abnormalities in MIA offspring
prenatally exposed to maternal inflammation.
Distinct populations of S1DZ neurons selectively modulate MIA behaviors
To gain insight into the downstream neural circuits involved in eliciting
MIA-associated behaviors, we next examined the efferent targets of the S1DZ. We
injected an anterogradely-labeling adeno-associated virus (AAV) driving EYFP into
the S1DZ and an AAV driving mCherry into either the S1FL or S1BF. These tracing
studies revealed that the S1DZ exhibits largely distinct efferent targets compared
to the S1FL and S1BF regions (Fig. 5a, b and
Extended Data Fig. 11). The S1DZ
selectively sends axons to a sub-region of M2, striatum as well as TeA. To test the
role of these distinct downstream regions in eliciting MIA-behaviors, we injected
retrogradely transported rabies virus (RV)
38
expressing EYFP, Chronos (excitatory opsin)
39
or ArchT (inhibitory
opsin)
40
into the TeA to
retrogradely label S1DZ neurons in WT animals (Fig.
5c, d). Photostimulation of Chronos-positive, TeA-projecting neurons in
the S1DZ generated sociability deficits without affecting total interaction time,
but failed to induce increased marble burying phenotypes (Fig. 5e–g and Extended Data
Fig. 12a–f). Photostimulation of EYFP- or
ArchT-expressing neurons did not produce any behavioral deficits. Thus, in otherwise
WT animals, increasing the neural activity of the neurons in the S1DZ that project
to the TeA recapitulated MIA-associated sociability deficits, but not the repetitive
marble burying phenotypes. Conversely, in MIA animals, decreasing the neural
activity of this S1DZ neuronal population with ArchT restored normal sociability,
but failed to suppress the enhanced marble burying phenotype (Fig. 5e–g and Extended
Data Fig. 12a–f). We also manipulated the activity of
the striatum-projecting S1DZ neurons and found that this population, when activated
using Chronos, induced enhanced marble-burying phenotype in WT animals without
modulating sociability. On the other hand, decreased neural activity in this
population suppressed the enhanced marble burying behavior without correcting
sociability deficits in MIA offspring (Fig.
5k–m and Extended Data Fig.
12g–l). The TeA- or striatum-projecting S1DZ populations equally
modulated the amount of time spent in the center of an arena in the open field assay
(Fig. 5h, n and Extended Data Fig. 12). These data suggest that the neurons in
S1DZ region projecting to the TeA or striatum selectively modulate interactions with
social targets and repetitive behaviors, respectively.
Discussion
Identifying neural circuits and components that modulate behaviors
aberrantly manifested in patients with neurodevelopmental disorders is critical for
developing therapeutic approaches. One challenge to achieving this goal is the
paucity of animal models in which discrete brain areas are known to mediate
disorder-associated behavioral symptoms. Here we identified a restricted brain
region centered on S1DZ as a component of the neural circuit that mediates
MIA-induced behavioral abnormalities. S1DZ has been implicated in proprioceptive
functions
13–15
. It will be crucial to elucidate
the nature of the afferent information to the S1DZ region and how this information
is differentially processed in the downstream targets of healthy and diseased
brains. Our data indicate that IL-17Ra expression in the fetal brain is necessary
to
mediate the MIA effects. The cell type impacted by IL-17Ra activation upon MIA, and
mechanisms by which the receptor activation induces cortical patches in S1 need to
be identified in the future. Furthermore, it is interesting to note that the main
efferent targets of the S1DZ, such as the TeA and M2, are also locations in which
cortical patches are frequently found in MIA offspring (Fig. 1b and Extended Data
Fig. 1b, d). This observation suggests that cortical patch formation in
MIA offspring may be intricately linked to concerted neural activity among the
connected brain regions. While similar cortical patches were observed in prefrontal
and temporal cortical tissues of children with autism
41
, it will be informative to examine whether
cortical patches are also found in S1 of human patients with neurodevelopmental
disorders. Of note, we cannot rule out a possibility that general MIA-induced
behavioral abnormalities are driven by heightened anxiety. It also should be noted
that in some MIA animals, cortical patches were only observed outside of S1 (12
% of animals, n=50), suggesting that S1DZ region might be one of the
nodes within a larger network that controls MIA-impacted behaviors. This MIA mouse
model with discrete, functionally-relevant perturbations in the S1DZ region, might
provide access to a network that modulates behaviors across different mouse models
of neurodevelopmental disorders.
Materials and Methods
Animals
All experiments were performed in accordance with the Guide for the Care
and Use of Laboratory Animals and were approved by the National Institutes of
Health and the Committee and Animal Care at Massachusetts Institute of
Technology. C57BL/6 mice were purchased from Taconic (USA), and
Nestin-cre (003771), PV-cre (008069), and
vGluT2-cre (016963) mice from Jackson laboratory (USA).
IL-17Rafl/lfl
mice were described
previously
42
. All mice
were crossed and maintained in-house with C57BL/6 mice from Taconic. Mice were
analyzed with the following primers for the presence of SFB using qPCR: SFB736-F
5′-GACGCTGAGGCATGAGAGCAT-3′, SFB844-R:
5′-GACGGCACGGATTGTTATTCA-3′ for SFB; UniF340
5′-ACTCCTACGGGAGGCAGCAGT-3′, UniR514
5′-ATTACCGCGGCTGCTGGC-3′ for total commensal bacteria.
IL-17Rafl/fl
animals were crossed with
Nestin-cre to remove IL-17Ra in the brain. The following
primers were used to genotype progenies: IL-17Ra-flox-1-F
5′-GGCAGCCTTTGGGATCCCAAC-3′, IL-17Ra-flox-2-R
5′-CTACTCTTCTCACCAGCGCGC-3′ for WT 336bps/Floxed 377bps;
IL-17Ra-flox-2-R, IL-17Ra-flox-3-F 5′-GTGCCCACAGAGTGTCTTCTGT-3′
for KO 478bps; and Cre-F 5′-GCGGTCTGGCAGTAAAAACTATC-3′, Cre-R
5′-GTGAAACAGCATTGCTGTCACTT-3′ for Nestin-cre 100bps. For gender
discrimination of each embryo, PCR was carried out using sry
(sex-determining region of the Y chromosome) gene specific primers:
5′-ACAAGTTGGCCCAGCAGAAT-3′, and
5′-GGGATATCAACAGGCTGCCA-3′.
Maternal Immune Activation
Mice were mated overnight and females were checked daily for the
presence of seminal plugs, noted as embryonic day 0.5 (E0.5). On E12.5, pregnant
female mice were weighed and injected with a single dose of poly(I:C) (20mg/kg
i.p., Sigma Aldrich, USA), which was incubated at 70°C for 20 min and
cooled down to 25°C for 1hr before injection. Each dam was returned to
its cage and left undisturbed until the birth of its litter. All pups remained
with the mother until weaning on postnatal day 21 (P21), at which time mice were
group-housed at a maximum of 5 per cage with same-sex littermates. For checking
the effect of poly(I:C) administration at different time points during
pregnancy, we injected poly(I:C) into pregnant dams on E12.5, E15.5, or
E18.5.
Stereotaxic injection
All surgeries were carried out using aseptic techniques and animals were
pre-operatively injected with the following dosages of anesthetics and
analgesics: ketamine (100mg/kg i.p.), xylazine (10mg/kg i.p.), and slow-release
buprenorphine (1mg/kg s.c.). All stereotaxic reference points were set at Bregma
for the AP axis, at the midline for the ML axis, and at the surface of the brain
for the DV axis. For optogenetic experiments, animals received bilateral
stereotaxic injections of one of the following viruses at rates of <0.1
ml/min: AAV2-hSyn-EYFP, AAV2-hSyn-ChR2:EYFP,
AAV2-hSyn-NpHR3.0:EYFP, AAV2-EF1a-DIO-Cre:EYFP,
AAV2-EF1a-DIO-ChR2:EYFP, or AAV2-EF1a-DIO-NpHR3.0:EYFP
(UNC vector core, USA). These viruses were injected into one of the following
coordinates: the cortical area near S1DZ (AP = −0.5 mm; ML
= ±2.5~3.0 mm; DV = 0.8 mm), off-targets
±0.5 mm or ±1.0 mm along the AP axis (AP = 0.5 mm, ML
= ±3.0 mm, DV = 0.8 mm; AP = 0.0 mm, ML
= ±3.0 mm, DV = 0.8 mm; AP = −1.0 mm, ML
= ±3.0 mm, DV = 0.8 mm; and AP = −1.5
mm, ML = ±3.0 mm, DV = 0.8 mm), S1FL (AP =
−0.5 mm, ML = ±2.0 mm, DV = 0.8 mm), or S1BF (AP
= −0.5 mm, ML = ±3.5 mm, DV = 0.8 mm).
Subsequently, fiber optic implants (300 μm core size, Thorlabs, USA)
were bilaterally placed 500 μm above the virus injection sites.
For stimulating the specific S1DZ/TeA and S1DZ/Striatum connections,
rabies virus (RV-EYFP, RV-Chronos:EYFP or RV-ArchT:EYFP; Ian R. Wickersham at
MIT) was bilaterally introduced into either the TeA (AP=−1.75
mm, ML= ±4.15 mm, DV=1.65 mm) or striatum (AP=
−0.2mm, ML= ±2.7mm, DV= 2.5mm) and optic fiber
implants were placed onto the S1DZ (AP = −0.5 mm, ML =
±2.5 mm, DV = 0.3 mm).
For anterograde tracing, AAV2-hSyn-EYFP was injected into the
S1DZ and AAV2-hSyn-mCherry into either the S1FL or S1BF.
All brain section schematics for showing virus injection sites and optic
fiber implantation sites were drawn using Adobe Illustrator to closely resemble
the corresponding sections in the Paxinos brain atlas
12
.
Behavioral analysis
All behavioral training and testing were carried out in accordance with
previously established behavioral schemes
11
with modifications. Animals were tested during light
cycle and were transferred to the behavior testing room with light control (80
lux) for 1hr before the start of experiments. Experimenters were blind to the
treatment group.
Ultrasonic vocalizations
On P9, mouse pup ultrasonic vocalizations (USVs) were detected for 3
min using an Ultra-Sound Gate CM16/CMPA microphone (AviSoft, Germany) and
SAS Prolab software (AviSoft, Germany) in a sound attenuation chamber under
stable temperature (19–22°C). For further characterization
of the USVs, the sonograms from the 1st minute of the recordings were
classified into ten distinct categories in accordance to previously
established methods
43
and
were analyzed for the total number of calls made and the average duration of
the calls.
Three-chamber social approach assay
Male mice (8~12-weeks-old) were tested for sociability using
a 3-chamber social approach paradigm. An empty object-containment cage
(circular metallic cages, Stoelting Neuroscience) was each placed into the
left and right chambers of a 3-chamber arena
(50cm×35cm×30cm), which the experimental mice freely
investigated for 10 min (exploration period / habituation). The following
day, the mice underwent another 10 min exploration period (habituation).
Immediately after, the mice were confined to the center chamber, while a
social object (unfamiliar C57BL/6 male mouse) and an inanimate object
(Rubber object of a similar size as the social object) were placed
alternatingly into either the left or right object-containment cage.
Barriers to the adjacent chambers were removed, and the mice were allowed to
explore the 3-chamber arena for 10 min. Approach behavior was defined as
interaction time (i.e. sniffing, approach) with targets in each chamber
(within 2 cm). Sessions were video-recorded and object approach behavior and
total distance moved were analyzed using EthoVision tracking system (Noldus,
Netherlands). % Interaction was calculated as the percentage of time
spent investigating the social target or the inanimate object out of the
total investigation time for both objects.
Marble burying test
Mice were placed into testing arenas (arena size:
40cm×20cm×30cm, bedding depth: 3cm) each containing 20 glass
marbles (laid out in four rows of five marbles equidistant from one
another). At the end of the 15-min exploration period, mice were carefully
removed from the testing cages and the number of marbles buried was
recorded. The marble burying index was arbitrarily defined as the following:
1 for marbles covered >50% with bedding, 0.5 for marbles
covered <50% with bedding, or 0 for anything less.
Open field test
Mice underwent a 15-min exploration period in the testing arena
(arena size: 50cm×50cm×35cm). Sessions were video-recorded
and analyzed for time spent in the center (center size: 25cm × 25cm)
using EthoVision Noldus tracking system (Noldus, Netherlands).
Behavioral analysis with optical stimulation
After two weeks of recovery, animals were assessed using the behavioral
schemes described above. During behavioral assays, animals were given 3 min of
laser stimulation (On session, ChR2: 405nm, 6mW, 20Hz, 50% duty cycle;
Chronos: 488nm, 6mW, 20Hz, 50% duty cycle; NpHR3.0 and ArchT: 595nm,
8mW, 20Hz, 50% duty cycle) followed by 3 min of no stimulation (Off
session). Animals started with either an On or Off session in a counterbalanced
manner. Photostimulation was controlled with a waveform generator (Keysight,
33220A, USA) and Ethovision XT (Noldus, Netherlands). Behavioral analysis was
conducted as described earlier using EthoVision Noldus tracking system (Noldus,
Netherlands).
For quantitative analysis of photostimulation-dependent activation of
virus expressing neurons, mice were sacrificed 1 hr after the end of the
behavioral testing. Brain slices were double-labeled for c-Fos (sc-7270, Santa
Cruz, USA; ABE457, Millipore, USA) and EYFP (ab5450, Abcam, USA). The percentage
of neurons expressing c-Fos
(c-Fos+EYFP+/EYFP+)
within a 500 μm × 500μm area, 300μm below the
optical fiber placement was calculated. Behavioral results from mice without
viral infection or with inaccurate targeting of virus or fiber implantations
were excluded. Experimenter was blind to the treatment groups.
Slice Preparation for Whole-Cell Electrophysiology
Mice were anesthetized with pentobarbital (40mg/kg i.p.) and
intracardially perfused with ice-cold dissection buffer (in mM: 87 NaCl, 2.5
KCl, 1.25 NaH2PO4, 26 NaHCO3, 75 sucrose, 10
dextrose, 1.3 ascorbic acid, 7 MgCl2 and 0.5 CaCl2)
bubbled with 95% O2-5% CO2. Brains were
rapidly removed and immersed in ice-cold dissection buffer. Somatosensory
cortical sections were dissected and 300μm coronal slices were prepared
using a Leica VT1200S vibratome (Leica, USA). Slices recovered for 20 min in a
35°C submersion chamber filled with oxygenated artificial cerebrospinal
fluid (aCSF) (in mM: 124 NaCl, 3 KCl, 1.25 NaH2PO4, 26
NaHCO3, 1 MgCl2, 2 CaCl2, and 20 glucose)
and then kept at room temperature for >40 min until use.
Voltage-Clamp Recordings
Miniature Inhibitory Postsynaptic Currents
To specifically isolate miniature inhibitory postsynaptic currents
(mIPSCs), slices were placed in a submersion chamber maintained at
32°C, perfused at 2 ml/min with oxygenated aCSF (as described above)
containing 1μM TTX, 100μM DL-APV, and 20μM DNQX and
held at 0mV. Cells were visualized using an Olympus BX-51 equipped with
infrared differential interference contrast (IR-DIC) optics. Pyramidal
neurons from Layer II/III of PBS control offspring or corresponding upper
portion of the cortex of MIA offspring were identified by intrinsic membrane
properties present in S1 and morphological confirmation of spiny dendrites.
Patch pipettes were pulled from thick-walled borosilicate glass (P-2000,
Sutter Instruments Novato, USA). Open tip resistances were between
2.5–6MΩ and were back-filled with an internal containing the
following (in mM): 100 CsCH3SO3, 15 CsCl, 2.5
MgCl2, 10 Hepes, 5 QX-314, 5 BAPTA, 4 Mg-ATP, 0.3 Mg-GTP, and
0.025 Alexa-568 with pH adjusted to 7.25 with 1M CsOH and osmolarity
adjusted to ~295 mOsm by the addition of sucrose or water.
Voltage-clamp recordings were performed in whole-cell configuration using
patch-clamp amplifier (Multiclamp 700B, Molecular Devices or Amplifier
BVC-700A, Dagan) and data were acquired and analyzed using pClamp 10
software (Molecular Devices) or a template matching algorithm in MatLab.
Pipette seal resistances were >1GΩ and pipette capacitive
transients were minimized before breakthrough. Changes in series and input
resistance were monitored throughout the experiment by giving a test pulse
every 30s and measuring the amplitude of the capacitive current. Slices were
subsequently fixed in 4% PFA for post-hoc validation. Cells were
discarded if series resistance rose above 20MΩ. The experimenter was
blinded during the acquisition and analysis of the postsynaptic
currents.
Immunohistochemistry
For cryosectioning, animals were intracardially perfused, and the brain
was dissected out, fixed with 4% PFA in PBS overnight at 4°C,
and cryoprotected in 30% sucrose solution. The left hemisphere was
marked with a needle and the sections were coronally sliced at 40μm
using a cryostat (Leica, USA). For vibratome sectioning, animals were
intracardially perfused, and the brain was fixed with 4% PFA in PBS
overnight at 4°C. The brains were coronally sliced at either 50 or
100μm with a Leica VT1000S vibratome (Leica, USA).
Slices were permeabilized with blocking solution containing 0.4%
Triton X-100 and 2% goat serum in PBS for 1 h at room temperature (RT)
and then incubated with anti-rabbit-TBR1 (ab31940, Abcam, USA), anti-mouse-SATB2
(ab51502, Abcam, USA), anti-rabbit-PV (PV27, Swant, Switzerland),
anti-rabbit-VIP (20077, Immunostar, USA), anti-mouse-NeuN (MAB377X, Millipore,
USA), or anti-rabbit-c-Fos (sc-7270, Santa Cruz, USA; ABE457, Millipore, USA)
antibodies overnight at 4°C. The following day, slices were incubated
with fluorescently conjugated secondary antibodies (Invitrogen, USA) for 1 hr at
RT with Neurotrace (Invitrogen, USA), and mounted in Vectashield mounting medium
containing 4′,6-Diamidino-2-Phenylindole, Dihydrochloride (DAPI; Vector
laboratories, USA). Images of stained slices were acquired using a confocal
microscope (LSM710; Carl Zeiss, Germany) with a 20X objective lens; all image
settings were kept constant across the same batch of experimental groups.
For anterograde-tracing, brains were sliced into 100μm sections,
and the prepared slices were labeled with anti-chicken-GFP (ab5450, Abcam, USA),
anti-rabbit-DsRed (632496, Clontech, USA) and DAPI. Images were acquired with a
confocal microscope and then aligned to the Paxinos brain atlas
12
.
Double In Situ Hybridization
E14.5 male embryos were obtained from dams treated with poly(I:C) at
E12.5. The heads were frozen on dry ice and embedded in Tissue Tek O.C.T.
(Sakura Finetek, Torrance, CA). The blocks were sectioned at 16μm
thickness using a cryostat (Leica, USA). Fluorescent in situ hybridization was
performed using an amplification technology according to the
manufacturer’s protocol (ViewRNA ISH Tissue Assay kit, Thermo Fisher
Scientific, USA). Briefly, the sections were fixed in 4% PFA at
4°C for 16–18 hr and dehydrated by sequentially soaking the
slides in 50%, 70%, and 100% ethanol.
il17ra (NM_008359, Cat#: VB1-10258),
ank3 (NM_170728, Cat#: VB6-17256), and
pax6 (NM_013627, Cat#: VB6-11573) probes were
applied to the sections and incubated for 3 h at 40°C.
In situ Hybridization followed by Immunohistochemistry
The sectioned embryo brain slices at 16μm thickness were fixed
in 4% PFA at RT for 10 min and were permeabilized in 70% ethanol
at 4°C for 12–18hr. Sections were further permeabilized in
RNase-free 8% SDS for 10min. Samples were rinsed to remove SDS, and
fluorescent in situ hybridization for il17ra transcripts were
performed according to the manufacturer’s protocol (ViewRNA ISH Tissue
Assay kit, Thermo Fisher Scientific, USA). The samples were subsequently
processed for immunohistochemistry with anti-NeuN antibody (MAB377X, Millipore,
USA).
Colocalization Coefficients for anterograde-tracing results
Percentage of co-localized projection fibers (co-localization
coefficient) from S1FL or S1BF with those from S1DZ was calculated using ImageJ
software (Manders’ coefficient) (Extended
Data Fig. 11). The co-localization coefficient was represented as
S1DZ/S1FL or S1FL/S1DZ and S1DZ/S1BF or S1BF/S1DZ. S1DZ/S1FL or S1DZ/S1BF
reflects the percentage of S1FL or S1BF projection fibers within the region of
interest (ROI) that is co-localized with those from S1DZ. S1FL/S1DZ or S1BF/S1DZ
reflects the percentage of S1DZ projection fibers co-localized with those from
S1FL or S1BF. Coste’s algorithm was used to define the threshold for
each image used in this experiment.
Analysis of cortical patches
Cortical patches were identified by the absence of SATB2 or TBR1
expression. Cortical regions that met the following criteria were not included
as cortical patches: (1) when the area had weak, but not the absence of, SATB2
or TBR1 expression; (2) when the area displayed tissue damage. Spatial locations
of the cortical patches were determined based on their distance from the midline
of the brain and the layer structures of the cortex. These locations were
matched to their corresponding regions in a mouse brain atlas (Paxinos brain
atlas)
12
.
For cortical patch analysis of the whole brain (Ext. Fig. 1), cortical patches were
drawn onto a
schematic derived form the Paxinos brain atlas
12
using Adobe Illustrator. For closer
analysis of those located within AP0.38~ −1.34 (Ext. Fig. 2), the brain section schematic
was drawn
using Adobe Illustrator in reference to the anatomical structures of the coronal
section at AP-0.46 in the Paxinos brain atlas
12
. The size of the cortical patches was
calculated using Zen Software (Carl Zeiss, Germany) and scaled using Adobe
Illustrator to reflect the actual size as accurately as possible.
Cell types within the cortical patches of the S1 were characterized by
staining brain slices from PBS and MIA offspring for PV, VIP or NeuN in
conjunction with SATB2 or TBR1. The cortical region of interest (width:
300μm), centered on a cortical patch in MIA offspring or the
corresponding area in PBS offspring, was divided into 10 equal laminar blocks
(bin) representing different depths of the cortex. Individual marker positive
cells (SATB2, PV, VIP, or NeuN) were quantified manually. VIP staining was
observed both in cells bodies as well as in processes; only the former was
included in counts. Experimenter was blind to the treatment groups.
Conventional RT-PCR
Total RNA was isolated from S1 of adult brains using Quick-RNA mini-prep
kits (Zymo, USA). cDNA was synthesized using 200μg total RNA using oligo
dT (PROTOSCRIPT FIRST STRAND CDNA SYNTHESIS KIT, NEB). For conventional RT-PCR,
1μl of cDNA synthesized as described above was diluted in 10μl
of KAPA Taq PCR kit (KAPA Biosystems). il17ra and
gapdh mRNA expression were assessed using the following
primers: Il17ra 5′-CCACTCTGTAGCACCCCAAT-3′ and
5′-CAGGCTCCGTAGTTCCTCAG-3′; gapdh
5′-CGACTTCAACAGCCTCCCACTCTTCC-3′ and
5′-TGGGTGGTCCAGGTTTCTTACTCCTT-3′.
Statistics and Reproducibility
Statistical analyses were performed using Prism software. The results
from behavioral experiments and quantification of individual marker-positive
cells were tested using One-way, Two-way, or Two-way repeated measures ANOVAs
followed by Tukey post-hoc tests, or unpaired two-tailed t-test. The correlation
between behavioral severity and cortical patch size was tested using Linear
regression. The distribution of cortical patches was tested using Kruskal-Wallis
test followed by Dunn post-hoc test. Sample sizes were chosen with adequate
power based on the literature as well as our previous studies, in general
without using statistical methods to predetermine sample size
11
. Animals were randomized into
different groups with approximately comparable numbers of animals in each group
whenever possible. No samples or data points were arbitrarily excluded from
statistical analysis. Key experiments, including the location of cortical
patches, anterograde tracing experiments, and behavioral experiments with
optical modulation, were all independently repeated with similar observations.
All data are represented as mean ± s.e.m.
Data availability
Source data containing raw data for the main and extended data figures
are available in the online version of the paper (Supplementary source data
tables). All other data are available from the corresponding authors
upon reasonable request.
Extended Data
Extended Data Fig. 1
Distribution of cortical patches in the cortex of MIA offspring
a, The locations of the cortical patches of 10
individual MIA animals were matched to their corresponding AP levels in the
Paxinos brain atlas. Different colors represent the patches from different
mice. The sub-regions, in which the cortical patches were observed in more
than 3 or 5 animals, are circled in blue or red, respectively. The mouse
brain in this figure has been reproduced with permission from Paxinos.
b, Prevalence of cortical patches in different cortical
sub-regions of the MIA offspring described in (a)
(n=10-mice/2-independent experiments). c, Prevalence of
cortical patches at different AP levels of the brain in the MIA offspring
described in (a) (n=10-mice/2-independent experiments).
Individual AP levels correspond to those in the schematic images of Extended
Data Fig. 1. d, The size and frequencies of cortical patches
found in different cortical sub-regions of the MIA offspring described in
(a) (n=10-mice/2-independent experiments). PrL:
Prelimbic, MO: Medial orbital, DLO: Dorsolateral orbital, DI: Dysgranular
insular, FrA: Frontal association cortex, M1: Primary motor cortex, M2:
Secondary motor cortex, S1: Primary somatosensory cortex, S2: Secondary
somatosensory cortex, V1: Primary visual cortex, V2: Secondary visual
cortex, AUD: Secondary auditory cortex, dorsal area, AU1: Primary auditory
cortex, AUV: Secondary auditory cortex, ventral area, Cg/RS:
Cingulate/Retrosplenial cortex, and TeA: Temporal association cortex.
* p<0.05, ** p<0.01 as calculated by
Kruskal-Wallis one-way ANOVA with Dunn post-hoc test (d).
Graphs indicate mean ± s.e.m.
Extended Data Fig. 2
Distribution of cortical patches located within 0.38 ~
−1.34 AP in the brains of MIA offspring
a, Schematics of the cortical patches located within
0.38~ −1.34 AP in the brains of MIA offspring plotted onto
the atlas plane near ~ −0.5 AP. The size of the cortical
patches in the schematic is scaled to reflect the actual size as accurately
as possible. Blue indicates the cortical patches from one hemisphere and red
from the other. The mouse brain in this figure has been reproduced with
permission from Paxinos. b, Representative images of the
cortical patches in the brains of MIA offspring (a) stained
with TBR1 or SATB2 and counterstained with DAPI. The number, locations, and
sizes of the cortical patches observed at a given AP level along with each
animal’s behavioral performance on the marble burying (marble
burying index), sociability (% Social target), and the time spent in
the center (s) of an open field are indicated. White arrows indicate
cortical patches. Scale bar represents 300μm.
Extended Data Fig. 3
MIA offspring display reduced inhibitory drive onto pyramidal neurons in
S1 cortical patches
a, Images cropped in layer I, II, and III of S1 and
stained for SATB2 (red) with PV, VIP, or NeuN (green) in offspring from PBS
(a) or Poly(I:C) (b) injected dams. Brain
slices are counterstained with DAPI (blue). White dotted lines indicate the
boundary of cortical patches in MIA offspring. Scale bar represents
100μm. For images shown in Fig.
1d. c. Representative traces of mIPSCs from
pyramidal neurons in S1DZ of PBS or MIA offspring. d–e,
Average population data depicting the frequency (d) and
amplitude (e) of pharmacologically isolated mIPSCs from S1DZ
pyramidal neurons described in (c) (n=14-biological
independent samples/6-mice/6-independent experiments and 12-biological
independent samples/6-mice/6-independent experiments from PBS and MIA
offspring, respectively). f, Representative traces of mIPSCs
from pyramidal neuron in S1DZ or med. S1BF of MIA offspring.
g–h, Average population data depicting the
frequency (g) and amplitude (h) of
pharmacologically isolated mIPSCs from S1 pyramidal neurons described in
(f) (n=7-biological independent
samples/3-mice/3-independent experiments and 7-biological independent
samples/3-mice/3-independent experiments for S1DZ and med. S1BF from MIA
offspring, respectively). i, Representative image of the S1,
stained for DAPI (blue) and c-Fos (green) from adult offspring of PBS- or
poly(I:C)-treated mother. Arrows indicate the boundaries of different
subregions in the S1. Scale bar represents 300μm. S1FL: Primary
somatosensory, forelimb, S1DZ: Primary somatosensory, dysgranular zone,
S1BF: Primary somatosensory, barrel field. j, Quantification of
c-Fos+ cells throughout the S1 (n=4 PBS and 4
Poly(I:C) mice/4-independent experiments). * p<0.05,
**p<0.01 as calculated by two-tailed unpaired t-test
(d,e,g,h,j). Graphs indicate mean ± s.e.m.
Extended Data Fig. 4
The development of MIA-associated behaviors depends on the time point at
which MIA is induced
a–c, Schematics of the marble burying test
(a), sociability test (b), and open field test
(c). d. Representative spectrographs of the
USVs for PBS and E12.5. e, The ultrasonic vocalization (USV)
index represents the number of USVs made by the pups (n=20, 24, 21,
and 22 mice for PBS, E12.5, E15.5, or E18.5 groups/5-independent
experiments). f–g, The sonograms of USVs emitted by the
pups are classified into ten distinct categories and analyzed for the number
of calls made and the duration of the calls (msec) within the 1st
minute of the recording (n=13 and 10 for pups from PBS- and
Poly(I:C)-injected mothers, respectively, at E12.5/3-independent
experiments). h–n, The marble burying index (the
percentage of marbles buried during the 15-min marble burying test)
(h), % time spent in social chamber during
habituation period of the sociability test (i), %
interaction during the sociability test (the percentage of time spent
investigating the social or inanimate stimulus out of the total exploration
time of both objects during the 10-min sociability test) (j),
the total interaction time (the total exploration time of both objects
during the 10-min sociability test) (k), the total distance
moved during the sociability test (l), the time spent in the
center of an open field (m), and the total distance moved
during the open field test (n) of the adult offspring described
in (e) (n= 12/19/15/9-mice, 7/7/7/5-independent experiments for
PBS/E12.5/E15.5/E18.5 groups). o–q, The size of
cortical patches found outside of S1 (within AP
0.38~−1.34mm) in offspring from dams injected with poly(I:C)
at E12.5 is plotted against the severity of the featured MIA phenotypes on
the marble burying test (o), sociability test as %
social target (the percentage of time spent investigating the social
stimulus out of the total exploration time of both objects)
(p), and open field test (q). Black solid lines
represent the regression line and gray dotted lines represent 95%
confidence intervals (n=19-mice/7-independent experiments) for E12.5
group. * p<0.05, ** p<0.01 as
calculated by two-tailed unpaired t-test (f,g), two-way ANOVA
with Tukey post-hoc tests (j), one-way ANOVA with Tukey
post-hoc tests (e,h,i,k,l,m,n), and Linear regression
(o,p,q). Graphs indicate mean ± s.e.m.
Extended Data Fig. 5
IL-17Ra expression is required in the fetal brain to induce behavioral
abnormalities upon MIA
a, Representative images of the embryonic cortex at
E14.5 stained for il17ra (green) and ank3,
NeuN or pax6 (red) in offspring from poly(I:C)-injected
dams. Brain slices were counterstained with DAPI (blue). Scale bar
represents 200μm. (n=3-mice/2-independent experiments)
b, Schematic showing the breeding scheme. Homozygous
IL-17Ra KO animals carrying Nestin-Cre transgene were crossed to homozygous
IL-17Ra conditional line (IL-17Rafl/fl). c,
il17ra and gapdh mRNA expression
levels in S1 of WT or IL-17Rafl/KO;Cre mice were measured using
conventional RT-PCR. Image indicates mRNA expression levels found in
individual animals (n=6-mice/2-independent experiments).
d, Representative images of SATB2 (red) expression in S1 of
offspring with indicated genotypes (WT, IL-17Rafl/KO, or
IL-17Rafl/KO;Cre) from mothers injected with PBS or
poly(I:C). Scale bar represents 100μm (n=5, 4, 7, and 8 mice
from WT (PBS), WT (Poly(I:C)), IL-17Rafl/KO (Poly(I:C)), and
IL-17Rafl/KO;Cre (Poly(I:C))/4-independent experiments).
e, Quantification of PV positive cells in regions centered
on S1 cortical patches around AP-0.46mm, divided into ten equal bins
representing different depths of the cortex, of MIA offspring or in
corresponding regions of PBS offspring with indicated genotypes
(n=5, 4, 7, and 8 mice from WT (PBS), WT (Poly(I:C)),
IL-17Rafl/KO (Poly(I:C)), and IL-17Rafl/KO;Cre
(Poly(I:C))/4-independent experiments). f, Quantification of
c-Fos+ cells in the S1 at around AP-0.46mm
(n=3, 3, 7, and 5 mice, from WT (PBS), WT (Poly(I:C)),
IL-17Rafl/KO (Poly(I:C)), and IL-17Rafl/KO;Cre
(Poly(I:C))/4-independnt experiments). g–j, The marble
burying index (g), the % interaction (h)
and the total interaction time (i) during the sociability test,
and the time spent in the center of an open field (j) of the
adult offspring described in (b) (n= 10, 8, 9, and 10
mice for WT (PBS), WT (Poly(I:C)), IL-17Rafl/KO (Poly(I:C)), and
IL-17Rafl/KO;Cre (Poly(I:C)) groups/5-independent
experiments). * p<0.05, ** p<0.01 as
calculated by two-way repeated measures ANOVA with Tukey post-hoc tests for
statistical comparison between the WT (Poly(I:C)) and
IL-17Rafl/KO;Cre (Poly(I:C)) (e), one-way ANOVA with
Tukey post-hoc tests (f,g,i,j), and two-way ANOVA with Tukey
post-hoc tests (h). Graphs indicate mean ± s.e.m.
Extended Data Fig. 6
Increasing neural activity in WT animals induces MIA behavioral
phenotypes
a, Representative images of c-Fos expression upon
photostimulation of the S1DZ in WT offsprings from mothers injected with PBS
at E12.5 (PBS offspring). In these animals,
AAV2-EF1α-DIO-EYFP, ChR2-EYFP, or NpHR-EYFP viruses were
targeted to the S1DZ. Coronal sections of the brains were stained for c-Fos
(red) and EYFP (green), and counterstained with neurotrace (NT, blue). Scale
bar represents 100um. b–f, The marble burying index
(the percentage of marbles buried during the 18-min marble burying test)
(b), the % social target (the percentage of time
spent investigating the social stimulus out of the total exploration time of
both objects) (c), the total interaction time during the
sociability test (d), the time spent in the center of an open
field (e), and the total distance moved during the open field
test (f) are plotted as averages from each individual 3-min
sessions. Light blue indicates the laser ‘On’ sessions
(‘Laser On-Off’: n=6, 5, and 8 mice/4-independent
experiments; ‘Laser Off-On’: n=6, 7, and 10
mice/4-independent experiments from the AAV2-hSyn-EYFP,
ChR2-EYFP, or NpHR-EYFP injected PBS offspring). * p<0.05,
** p<0.01 as calculated by two-way repeated measures
ANOVA with Tukey post-hoc tests. Graphs indicate mean ± s.e.m.
Extended Data Fig. 7
Increasing neural activity in vGluT2-positive neurons or decreasing
neural activity in PV-positive neurons of WT animals creates MIA behavioral
phenotypes
a,g, Representative images of c-Fos
expression upon photostimulation of the S1DZ in vGluT2-Cre (a)
or PV-Cre (g) animals injected with
AAV2-EF1α-DIO-EYFP, ChR2-EYFP, or NpHR-EYFP viruses.
Coronal sections of the brains were stained for c-Fos (red) and EYFP
(green), and counterstained with neurotrace (NT, blue). Scale bar represents
100um. b–l, The marble burying index, the %
social target, the total interaction time during the sociability test, the
time spent in the center of an open field, and the total distance moved
during the open field test with vGluT2-cre (b–f) and
PV-cre (h–l) animals are plotted as averages from each
individual 3-min sessions. Light blue indicates the laser
‘On’ sessions (‘Laser On-Off’: n=5,
8, and 6 mice, 4-independent experiments; ‘Laser Off-On’:
n=5, 9, and 5 mice, 5-independent experiments for vGluT2-Cre animals
injected with AAV2-EF1α-DIO-EYFP, ChR2-EYFP, or
NpHR-EYFP; ‘Laser On-Off’: n=7, 6, and 8 mice,
6-independent experiments; ‘Laser Off-On’: n=6, 6,
and 7 mice, 5-independent experiments for PV-Cre animals injected with
AAV2-EF1α-DIO-EYFP, ChR2-EYFP, or NpHR-EYFP).
* p<0.05, ** p<0.01 as calculated by
two-way repeated measures ANOVA with Tukey post-hoc tests. Graphs indicate
mean ± s.e.m.
Extended Data Fig. 8
The ability to create MIA behavioral phenotypes by increasing neural
activity in WT animals is specific with respect to the AP level and the
sub-region of the primary somatosensory cortex
a, Schematics (top) and representative images (bottom)
of the five sites in the S1 of WT animals injected with either
AAV2-hSyn-EYFP or AAV2-hSyn-ChR2-EYFP virus
(green) (AP= +0.5, +0.0, −0.5, −1.0,
or −1.5mm). The mouse brain in this figure has been reproduced with
permission from Paxinos. Scale bar represents 300μm. b,
Representative images of c-Fos expression upon photostimulation of the
injection sites in animals as prepared in (a). Coronal sections
of the brains were stained for c-Fos (red) and EYFP (green), and
counterstained with neurotrace (NT, blue). Scale bar represents
100μm. c, The percentage of EYFP+
neurons expressing c-Fos upon photostimulation of the injection site
(n=5 for WT animals injected with AAV2-hSyn-EYFP at
AP=−0.5mm and n=5, 5, 5, 5, and 5 for animals
injected with AAV2-hSyn-ChR2-EYFP at AP=0.5, 0.0,
−0.5, −1.0, or −1.5mm, 3-independent experiments,
respectively). d–f, The marble burying index
(d), the % interaction (during the 1st
laser-on session) of the sociability test (e), and the total
interaction time (during the 1st laser-on session) of the
sociability test (f) for animals prepared as in
(a) (n=12 for WT animals injected with
AAV2-hSyn-EYFP at AP=−0.5mm and n=12, 12,
12, 12, and 12 for those injected with AAV2-hSyn-ChR2-EYFP at
AP=0.5, 0.0, −0.5, −1.0, or −1.5mm,
6-independent experiments, respectively). g, A schematic
showing the superimposed virus injection sites from individual WT animals,
in which AAV2-hSyn-ChR2-EYFP was delivered into the S1FL (blue),
S1DZ (red), or S1BF (green). The mouse brain in this figure has been
reproduced with permission from Paxinos. h, Representative
images of c-Fos expression upon photostimulation of the injection sites
shown in (g). Coronal sections of the brains were stained for
c-Fos (red) and EYFP (green), and counterstained with neurotrace (NT, blue).
Scale bar represents 100μm. i, The percentage of
EYFP+ neurons co-expressing c-Fos upon
photostimulation of the injection site (n=7 mice for EYFP and 8 mice
for S1FL, S1DZ, and S1BF; 3-independent experiments).
j–l, The marble burying index (j), the
% interaction (during the 1st laser-on session) of the
sociability test (k), and the total interaction time (during
the 1st laser-on session) of the sociability test
(l) for animals prepared as in (g) (n=7
for WT animals injected with AAV2-hSyn-EYFP into S1DZ and
n=10, 12, and 10 for WT animals injected with
AAV2-hSyn-ChR2-EYFP into S1FL, S1DZ, or S1BF; 3-independent
experiments). S1HL: Primary somatosensory, hindlimb, S1FL: Primary
somatosensory, forelimb, S1: Primary somatosensory cortex, S1DZ: Primary
somatosensory, dysgranular zone, S1BF: Primary somatosensory, barrel field,
S1ShNc: Primary somatosensory, shoulder and neck, S1Tr: Primary
somatosensory, trunk. * p<0.05, **
p<0.01 as calculated by two-way ANOVA with Tukey post-hoc tests
(e,k) and one-way ANOVA with Tukey post-hoc tests
(c,d,f,i,j,l). Graphs indicate mean ± s.e.m.
Extended Data Fig. 9
Unilateral increase in neural activity of the S1DZ region creates MIA
behaviors in WT animals
a, Schematic showing the unilateral virus injection and
optic-fiber implantation in the S1DZ of WT animals injected with
AAV2-hSyn-EFYP, ChR2-EYFP, or NpHR-EFYP. The mouse brain in
this figure has been reproduced with permission from Paxinos.
b, Representative images of c-Fos expression upon
photostimulation of the injection sites shown in (a). Coronal
sections of the brains were stained for c-Fos (red) and EYFP (green), and
counterstained with DAPI (blue). Scale bar represents 100μm.
c, The percentage of EYFP+ neurons
co-expressing c-Fos upon photostimulation of the injection site
(n=9, 10, and 6 mice for WT animals injected with
AAV2-hSyn-EYFP, ChR2-EYFP, or NpHR-EYFP into S1DZ; 3-independent
experiments). d, The number of c-Fos+ cells in the
contralateral hemisphere of the injection site for the animals described in
(c). e–h, The marble burying index
(e), the % interaction (during the 1st
laser-on session) of the sociability test (f), the total
interaction time (during the 1st laser-on session) of the
sociability test (g), the time spent in the center of an open
field (during the 1st laser-on session) (h), and the
total distance moved during the open field test (during the 1st
laser-on session) (i) of animals prepared as in
(a) (n=9, 12, and 10 for WT animals injected with
AAV2-hSyn-EYFP, ChR2-EYFP, or NpHR-EYFP into S1DZ;
3-independent experiments). * p<0.05, **
p<0.01 as calculated by two-way ANOVA with Tukey post-hoc tests
(f) and one-way ANOVA with Tukey post-hoc tests
(c,d,e,g,h,i). Graphs indicate mean ± s.e.m.
Extended Data Fig. 10
Reducing neural activity in the cortical region centered on the S1DZ
corrects the behavioral abnormalities of MIA offspring
a, Quantification of c-Fos+ cells in
the S1DZ of adult offspring from mothers injected with PBS or Poly(I:C), and
of adult Poly(I:C) offspring, in which AAV2-hSyn-EYFP was
injected into the S1DZ (n=5, 4, and 4 mice for PBS, Poly(I:C), and
Poly(I:C);EYFP groups, respectively; 3-independent experiments).
b, AAV2-hSyn-EYFP was targeted into the S1DZ of
adult offspring from either PBS or Poly(I:C) treated mothers. The
accumulation of marble burying index over their behavioral session is
plotted based on the laser schemes (‘Laser On-Off’:
n=7 and 7; ‘Laser Off-On’: n=7 and7 for
AAV2-hSyn-EYFP injected PBS and Poly(I:C) offspring;
3-independent experiments, respectively). c–g,
AAV2-hSyn-EYFP, ChR2-EYFP, or NpHR-EYFP viruses were targeted
to the S1DZ of MIA offspring (poly(I:C)). The marble burying index
(c), the % social target (d) and the
total interaction time (e) of the sociability test, the time
spent in the center of an open field (f), and the total
distance moved during the open field test (g) are plotted as
averages from each individual 3-min sessions. Light blue indicates the laser
‘On’ sessions (‘Laser On-Off’: n=6,
5, and 10; ‘Laser Off-On’: n=5, 5, and10 for
AAV2-hSyn-EYFP, ChR2-EYFP, or NpHR-EYFP injected MIA
offspring; 5-independent experiments). * p<0.05,
** p<0.01 as calculated by one-way ANOVA with Tukey
post-hoc tests (a) and two-way repeated measures ANOVA with
Tukey post-hoc tests (b,c,d,e,f,g). Graphs indicate mean
± s.e.m.
Extended Data Fig. 11
The S1FL, S1DZ, and S1BF exhibit distinct efferent targets
a,c, AAV2-hSyn-mCherry and
AAV2-hSyn-EYFP were injected into the S1FL and S1DZ
(a) or S1BF and S1DZ (c), respectively. The
two cortical regions project to distinct sub-regions of the M2, the
striatum, and the associative cortices. Representative images are aligned to
their corresponding AP levels in the Paxinos brain atlas (n=5).
Scale bar represents 1mm. b,d, Quantification of percentage of
co-localized projection fibers, represented as % co-localization,
from S1FL with those from S1DZ within the regions of interest (ROI;
n= 5) (b) and from S1BF with those from S1DZ within the
regions of interest (ROI;n=5) (d). S1DZ/S1FL
(S1DZ/S1BF) reflects the percentage S1FL (S1BF) projection fibers within the
ROI co-localized with those from S1DZ, while S1FL/S1DZ (S1BF/S1DZ) reflects
vice versa. The mouse brain in this figure has been reproduced with
permission from Paxinos. Graph indicates mean ± s.e.m.
Extended Data Fig. 12
Distinct populations of S1DZ neurons projecting to TeA or Striatum
selectively modulate marble burying and sociability phenotypes
a, Percentage of EYFP/c-Fos co-expressing neurons upon
stimulation of animals described in Fig.
5c (n=6/6/6/6-mice, 3-independent experiments
(PBS;RV-EYFP/Chronos/ArchT, MIA;RV-ArchT)). b–f,
Performance on the marble burying test (b) (‘Laser
On-Off’: n=4/8/5/7-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 4/7/5/7-independent experiments
and ‘Laser Off-On’: n=5/5/5/5-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 5/5/5/5-independent experiments),
the % social target (c) and the total interaction time
during the sociability test (d) (‘Laser
On-Off’: n=4/6/9/9-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 4/5/7/7-independent experiments
and ‘Laser Off-On’: n=6/6/6/6-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 5/5/5/5-independent experiments),
and the time spent in center (e) and the total distance moved
during the open field test (f) (‘Laser On-Off’:
n=4/4/3/5-mice for PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT,
4/4/3/5-independent experiments and ‘Laser Off-On’:
n=3/3/4/6-mice for PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT,
3/3/4/5-independent experiments). g, Percentage of EYFP/c-Fos
co-expressing neurons upon stimulation of animals described in Fig. 5i (n=6/6/6/6-mice,
3-independent experiments (PBS;RV-EYFP/Chronos/ArchT, MIA;RV-ArchT)).
h–l, Performance on the marble burying test
(h) (‘Laser On-Off’: n=4/4/4/4-mice
for PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 4-independent experiments and
‘Laser Off-On’: n=3/4/4/4-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 3-independent experiments), the
% social target (i) and the total interaction time
during the sociability test (j) (‘Laser
On-Off’: n=4/3/3/3-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 3-independent experiments and
‘Laser Off-On’: n=3/3/3/4-mice for
PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT, 3-independent experiments), and
the time spent in center (k) and the total distance moved
during the open field test (l) (‘Laser On-Off’:
n=3/5/4/6-mice for PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT,
3/5/4/5-independent experiments and ‘Laser Off-On’:
n=2/4/4/4-mice for PBS;EYFP/PBS;Chronos/PBS;ArchT/MIA;ArchT,
2/4/4/4-independent experiments).
Supplementary Material
1