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Changes in laboratory mice after observation of deceased
conspecifics: a pilot suicidality study in animals
Daejong Jeon1,*, Sangwoo Kim2,*, Sang Kun Lee2, Kon Chu2
1Advanced Neural Technologies, Co., Seoul, Korea
2
Laboratory for Neurotherapeutics, Department of Neurology, Biomedical Research Institute, Seoul National University Hospital, Seoul,
Korea
Original Article
pISSN 2765-4559 eISSN 2734-1461
encephalitis [Epub ahead of print]
https://doi.org/10.47936/encephalitis.2021.00080
Received: May 20, 2021 Revised: June 7, 2021 Accepted: June 11, 2021
Correspondence: Sang Kun Lee
Department of Neurology, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea
E-mail: sangkun2923@gmail.com
ORCID: https://orcid.org/0000-0003-1908-0699
Kon Chu
Department of Neurology, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea
E-mail: stemcell.snu@gmail.com
ORCID: https://orcid.org/0000-0001-5863-0302
*These authors contributed equally to this study as co-first authors.
Purpose
Suicidality can be a serious feature of psychiatric symptoms in encephalitis. Investigating the psychiatric behavior associated with suicidality in
animal models of encephalitis is important; thus, determining whether normal laboratory animals are aware of death is necessary.
Methods
To examine the behavioral and brain activity changes associated with death of conspecifics, laboratory mice were exposed to a cadaveric mouse
or an anesthetized mouse. Behavioral tasks associated with anxiety and locomotion were conducted after repeated exposure. Neural activity in
the medial prefrontal cortex during the cadaver exploration was investigated using electroencephalographic recordings.
Results
During repeated exposure, mice in the cadaver group showed a gradual decrease in time exploring the cadaver, which was not observed in mice
in the anesthesia group. The cadaver group also exhibited increased levels of anxiety in the light/dark transition and elevated plus maze tasks
and displayed increased locomotor activity in the open field test. In an electrophysiological study, different brain oscillations were observed when
mice were exposed to a cadaveric mouse and an anesthetized mouse. Enhanced delta-band activity and reduced theta- and alpha-band activi-
ties were observed during cadaver exploration.
Conclusion
The present study results showed that experiences involving dead conspecifics strongly affect mouse behavior and brain activity. These findings
may be helpful in treating patients with psychiatric symptoms and aid in understanding the concept of death recognition/awareness in laborato-
ry animals.
Keywords: Encephalitis, Suicidality, Laboratory mice, Psychiatric behaviors, Electroencephalography
Copyright © 2021 by The Korean Encephalitis and Neuroinammation Society
This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licens-
es/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
encephalitisjournal.org encephalitis [Epub ahead of print] 1
Introduction
Encephalitis can often be accompanied by emotional and psy-
chological problems, such as anxiety, depression, and mood
swings. In antibody-mediated autoimmune encephalitis, such
as anti-N-methyl-D-aspartate receptor encephalitis, the degree
of psychiatric symptoms is severe. In addition, suicidality can be
a serious feature of psychiatric symptoms in encephalitis [1].
Therefore, studying suicidality in animals can be helpful in
treating patients with psychiatric brain disorders.
Many nonhuman mammalian species show unique responses
to dead conspecifics, such as remaining next to the deceased
conspecific, vocalizations, grooming, licking, or carrying the
body [2-6]. To date, whether these behavioral observations are
relevant to human behaviors regarding death, including
death-related psychological states (e.g., grief, mourning, be-
reavement, and lamentation) and fear or anxiety of mortality re-
mains unclear. However, animals presumably exhibit such be-
haviors because they can distinguish between life and death
and recognize death as something other than living [3,7-10].
In the wild, animals may occasionally observe dying conspecif-
ics or may encounter dead conspecifics due to events such as
aging, disease, or enemy attack. This experience may be trau-
matic as the animals come to recognize or become aware of
death. However, animals that live in a laboratory cannot have
such observational experiences involving dead bodies of their
conspecifics owing to animal welfare practices and the control
of experiments in accordance with the guidelines of the Institu-
tional Animal Care and Use Committee [11]. Thus, whether lab-
oratory animals can discriminate between living and dead con-
specifics, and between life and death, remains unclear. If labora-
tory animals can process this distinction, their responses and
the importance of these experiences remain unclear. Answers to
these questions may provide basic information regarding ani-
mal thanatology and for suicidality studies in animals as well as
help elucidate the evolutionary origins of death-related behav-
iors.
Mice are commonly used experimental animals. They are highly
social and even display empathy-like behaviors toward each
other [12-15]. Thus, mouse models can be useful for assessing
the neurobiological correlates of death recognition. In the pres-
ent pilot suicidality study, laboratory animals were used to de-
termine how a dead body (cadaver) of a conspecific affected
mouse behavior and behavioral changes were compared with
those elicited using anesthetized mice. Furthermore, neural ac-
tivity in the medial prefrontal cortex (mPFC) during cadaver ex-
ploration was investigated using electrophysiological assess-
ment in vivo.
Methods
Animals and treatments
Male C57BL/6 mice were used in the present study. Animals
were maintained with free access to food and water under a 12-
hour light/dark cycle. All experiments were approved by the In-
stitutional Animal Care and Use Committee in Seoul National
University Hospital (SNUH-IACUC, No. 14-0210-S1A1) and ani-
mals were maintained in the facility accredited AAALAC Inter-
national (#001169) in accordance with Guide for the Care and
Use of Laboratory Animals 8th edition (National Research
Council 2011). All efforts were made to minimize suffering. The
overall study consisted of two major experiments shown in
Figure 1A. Mice 10–12 weeks old were used as subject mice and
divided into two groups: (1) cadaver group, exposed to a cadav-
eric conspecific; (2) anesthesia group, exposed to an anesthe-
tized conspecific. Age-matched male C57BL/6 mice that had
been used for other behavioral experiments and were sched-
uled to be sacrificed were used as cadaveric or anesthetized
mice. The mice scheduled to be used as cadaveric mice were
sacrificed using CO2 immediately prior to each experiment. The
mice scheduled to be used as anesthetized mice were deeply
anesthetized with an intraperitoneal injection of ketamine (70
mg/kg) and xylazine hydrochloride (10 mg/kg) immediately
prior to each experiment.
Social investigation of a cadaver and an anesthetized
mouse target
The experiment was performed as previously described [16]. A
single subject mouse was allowed to roam freely in a clean cage
(22 × 19 × 17 cm, 3-cm sawdust layer) for 10 minutes. The cag-
es used were identical to cages in which the mice were normally
housed. After the 10-minute period, a cadaveric or anesthetized
male mouse (target mouse) was placed in the middle of the
cage. Then, the subject mouse was allowed to roam freely for 15
minutes (test session). Behavior toward the target mouse was
video-recorded for 15 minutes and the duration of contact
(sniffing, touching, and climbing) were measured and analyzed
for 5 or 10 minutes. A mouse was considered to be sniffing the
target mouse when its head was facing the target mouse within
1 inch. The cage, target mouse, and sawdust were changed for
every subject mouse. This experiment was repeatedly per-
formed once a day for 3 days.
encephalitisjournal.org
Daejong Jeon et al. Mouse responses to deceased conspecifics
2encephalitis [Epub ahead of print]
Elevated plus maze and light/dark transition
For assessment of anxiety, elevated plus maze and light/dark
transition tasks were performed as previously described
[13,16,17]. The elevated plus maze was made of plastic and con-
sisted of two white open arms (25 × 8 cm), two black enclosed
arms (25 × 8 × 20 cm), and a central platform (8 × 8 × 8 cm) in
the form of a cross. The maze was placed 50 cm above the floor.
Mice were individually placed in the center with their heads di-
rected toward one of the closed arms. The total time spent in
each arm or in the center was analyzed by video monitoring for
5 minutes. An arm entry was defined and counted when all four
paws crossed from the center into an arm and was used for
measuring the amount of time spent in each arm.
For the light/dark transition task, a light/dark box (30 × 45 × 27
cm) made of plastic comprised of a dark compartment (one
third of the total area) and light compartment with a hole in the
middle. The light compartment was illuminated at 400 lux. The
elapsed time to entry (all four paws) into the light compartment
(latency) and the amount of time (duration) spent in each com-
partment were measured over a 5-minute period by video mon-
itoring.
Open field test
To assess locomotor activity, the open field test was performed
as previously described [13,18]. The open field box was made of
white plastic (40 × 40 × 40 cm). Individual mice were placed in
the periphery of the field and the paths of the animals recorded
with a video camera. The total distance traveled for 10 minutes
was analyzed using a software program (EthoVision XT; Noldus
Information Technology, Wageningen, The Netherlands).
In vivo electrophysiology for electroencephalographic
Electroencephalographic (EEG) surgery and recording in vivo
were performed as previously described [13,18,19]. For EEG
monitoring during a social behavioral task, nine naïve mice
were subjected to EEG surgery 1 week before the experiment.
For surgery, the animals were anesthetized with an intraperito-
neal injection of ketamine (90 mg/kg) and xylazine hydrochlo-
ride (40 mg/kg). Electrode implantation was performed using a
stereotaxic apparatus (Kopf Instruments, Tujunga, CA, USA).
EEG recordings were obtained with tungsten electrodes (0.005
in, 2 MΩ), positioned in the mPFC (anterior-posterior, −1.94 to
–1.70 mm; medial-lateral, 0.25–0.45 mm; and dorsal-ventral,
2.75 mm) from the bregma with grounding over the cerebellum.
The electrodes were fixed to the skull with cyanoacrylate adhe-
sive and dental acrylic cement. After a 1-week recovery from
brain surgery, animals were placed in a small acrylic cage (15 ×
20 × 15 cm) and allowed to move freely in the cage. EEG record-
ings combined with video monitoring were performed simulta-
neously during the behavioral task on social investigation of a
Figure 1 Experimental design and social investigation of a cadaver
Social investigation (day 1 to 3)
Social investigation with EEG recording
1)
2)
300
250
200
150
100
50
0
500
400
300
200
100
0
Duration (sec)
Duration (sec)
■ Anesthesia group
■ Cadaver group
■ Anesthesia group
■ Cadaver group
1 12 23 3(day) (day)
##
##
*
*
**
*
Behavioral tasks: EPM/LD/OP (day 4 to 8)
A
B C
(A) Simple schematic for the experiments: 1) Behavioral tasks after the social investigation of a cadaveric mouse target or an anesthetized mouse target for 3 days; 2)
electroencephalographic (EEG) recordings during the social investigation. (B, C) In the 3-day social investigation of a cadaveric mouse target or an anesthetized mouse tar-
get, the contact duration was assessed for the first 5 minutes (B) and 10 minutes (C) on each day. The duration of contact in the cadaver group, but not in the anesthesia
group, continued to decrease for 3 days, and the cadaver group showed reduced duration of contact compared with the anesthesia group.
EPM, elevated plus maze; LD, light/dark transition; OP, open field.
Comparison between the two groups: *p < 0.05, **p < 0.01; Student t-test. Comparison within each group: ##p < 0.01; one-way analysis of variance.
Daejong Jeon et al. Mouse responses to deceased conspecifics
encephalitisjournal.org encephalitis [Epub ahead of print] 3
cadaveric conspecific or an anesthetized conspecific. Subject
mice were sequentially exposed to anesthetized or cadaveric
conspecifics at 15-minute intervals. The order of exposure to
targets was random. Two epochs (10 seconds each) of EEG sig-
nals during exploration of the conspecific by each mouse, from
1 to 3 minutes after the start of the behavioral task, were ran-
domly selected and used for analysis. The five EEG frequency
bands, delta (1.5–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), beta
(12–30 Hz), and gamma (30–60 Hz), were analyzed for EEG
power. The relative normalized power at each individual fre-
quency was presented as a fraction of the sum of powers at all
frequencies. The electrical activities were recorded after amplifi-
cation (× 12,000), bandpass filtering from 0.1 to 100 Hz, and dig-
itization at a 400 Hz sampling rate (AS 40) with a digital electro-
encephalography system (Comet XL; Astro-Med, Inc., Warwick,
RI, USA). EEG-video data obtained were analyzed offline using
PSG Twin (Astro-Med) and Clampfit (Axon Instruments, Foster
City, CA, USA).
Statistical analysis
All data are presented as means ± standard error of the mean.
Analysis of variance (ANOVA) was used to conduct multiple
comparisons of means. Student t-test was performed to deter-
mine statistical differences between two means. A p-value <
0.05 was considered statistically significant.
Results
Reduced social investigation of cadaver
To determine how laboratory mice are affected by a dead con-
specific, mice were first allowed to explore a dead conspecific
(cadaver). The social investigative activity was assessed as dura-
tion of contact with the target (a cadaver or an anesthetized
mouse). On the first day, the cadaver (exposed to a cadaveric
conspecific) (n = 17; 147.88 ± 15.65 seconds over 5 minutes,
Figure 1B; 232.93 ± 33.04 seconds over 10 minutes, Figure 1C)
and anesthesia groups (exposed to an anesthetized conspecific)
(n = 13; 145.32 ± 9.56 seconds over 5 minutes, Figure 1B; 199.45
± 19.56 seconds over 10 minutes, Figure 1C) spent a similar
amount of time in contact with their targets. However, on the
second day, the cadaver group (114.72 ± 11.96 seconds over 5
minutes, Figure 1B; 170.08 ± 21.46 seconds over 10 minutes,
Figure 1C) showed a significantly shorter contact duration than
the anesthesia group (170.85 ± 21.89 seconds over 5 minutes, p
< 0.05, Student t-test, Figure 1B; 301.20 ± 42.81 seconds over 10
minutes, p < 0.01, Student t-test, Figure 1C). Similarly, on the third
day, the cadaver group (76.92 ± 10.78 seconds over 5 minutes,
Figure 1B; 114.85 ± 15.60 seconds over 10 minutes, Figure 1C)
showed a significantly shorter contact duration than the anes-
thesia group (116.25 ± 15.52 seconds over 5 minutes, p < 0.05,
Student t-test; Figure 1B; 178.78 ± 19.15 seconds over 10 min-
utes, p < 0.05, Student t-test; Figure 1C). Notably, the contact du-
ration in the cadaver group gradually became shorter from day 1
to day 3 (F2, 48 = 7.50, p < 0.01, one-way ANOVA, Figure 1B; F2, 48
= 5.83, p < 0.01, one-way ANOVA, Figure 1C); however, the an-
esthesia group showed no difference (F2, 36 = 2.85, p = 0.07, one-
way ANOVA; Figure 1B) or increase on day 2 (F2, 36 = 4.85, p <
0.05, one-way ANOVA; Figure 1C). The results indicated that ex-
ploratory activities differed depending on social targets and
mice respond to a dead conspecific in a manner different from
their response to a living anesthetized conspecific.
Cadaver group showed increased anxiety levels and
locomotor activity
After the 3-day exposure experiment, the cadaver and anesthe-
sia groups were subjected to elevated plus maze, light/dark
transition, and open field tests to assess anxiety and locomotion.
In the elevated plus maze task (Figure 2A), both the cadaver (n
= 17, 10.00 ± 2.78 seconds) and anesthesia groups (n = 13, 7.35
± 2.49 seconds) spent less time in the open arms than the con-
trol group (n = 17, 24.62 ± 3.02 seconds, F2, 43 = 11.10, p <
0.001, one-way ANOVA). In addition, the cadaver (251.96 ± 6.54
seconds) and anesthesia groups (261.72 ± 4.56 seconds) spent
more time in the closed arms than the control group (229.84 ±
5.91 seconds, F2, 43 = 7.67, p < 0.01, one-way ANOVA). Signifi-
cant differences were not observed between the cadaver and
anesthesia groups.
In the light/dark transition task (Figure 2B), the cadaver group (n
= 16, 165.80 ± 25.10 seconds) displayed a longer latency in the
light compartment compared with the control group (n = 17,
93.09 ± 16.74 seconds, p < 0.05, Student t-test). Furthermore,
the cadaver group displayed longer and shorter amounts of time
in the dark (cadaver, 257.93 ± 10.78 seconds; control, 226.03 ±
7.64 seconds, p < 0.05, Student t-test) and light compartments
(cadaver, 42.07 ± 10.38 seconds; control, 73.97 ± 7.64 seconds,
p < 0.05, Student t-test), respectively, compared with the control
group. However, the anesthesia group spent a similar amount of
time in each compartment compared with the control group.
To assess locomotor activity, an open field test was performed.
Mice in the cadaver group traveled a greater distance (n = 15,
3,758.78 ± 106.85 cm) than mice in the control group (n = 17,
3,323.42 ± 95.95 cm, p < 0.01, Student t-test). However, mice in
the anesthesia group (n = 13, 3,395.06 ± 90.06 cm) traveled a
distance similar to mice in the control group.
encephalitisjournal.org
Daejong Jeon et al. Mouse responses to deceased conspecifics
4encephalitis [Epub ahead of print]
Figure 2 Behavioral alterations in mice exposed to a cadaver
A
B
C
300
250
200
150
100
50
0
300
250
200
150
100
50
0
6,000
5,000
4,000
3,000
2,000
1,000
0
Time (sec)Time (sec)Distance (cm)
Open arm
First time to Light
Closed arm
Light
Center
Dark
■ Control
■ Anesthesia group
■ Cadaver group
■ Normal
■ Anesthesia group
■ Cadaver group
■ Control
■ Anesthesia group
■ Cadaver group
##
##
*
*
**
*
(A) Elevated plus maze task: the cadaver and anesthesia groups spent less and
more time in the open and closed arms, respectively, than the control group. There
was no difference between the cadaver and the anesthesia groups. Comparison
among groups: ##p < 0.01; one-way analysis of variance. (B) Light/dark transition
task: the cadaver group, but not the anesthesia group, showed a longer latency to
enter the light compartment, spent less time in the light compartment, and spent
more time in the dark compartment than the control group. There was no differ-
ence between the control and the anesthesia groups. Comparison with control
group: *p < 0.05; Student t-test. (C) Open field test: the cadaver group, but not the
anesthesia group, exhibited an increase in total distance traveled in the open field
box compared with the control group. There was no difference between the control
and anesthesia groups. Comparison with control or anesthesia group: **p < 0.01;
Student t-test.
Taken together, these results demonstrated that mice exposed to
a cadaveric conspecific had increased levels of anxiety and loco-
motor activity compared with naïve control mice or mice ex-
posed to an anesthetized conspecific.
Differences in brain oscillations in the medial
prefrontal cortex during exploration of cadaveric
and anesthetized mice
The mPFC has an important role in social cognitive behavior,
including novelty detection and fear recognition [20-26]. EEG
signals were measured from the mPFC while mice investigated
cadaveric and anesthetized conspecifics (Figure 3A) and brain
oscillations compared using a frequency-wise power spectrum
analysis. During exploration of a cadaver, subject mice showed
significantly enhanced delta-band activity and reduced theta-
and alpha-band activities in the mPFC relative to their activities
during exploration of an anesthetized conspecific (p < 0.05,
Student t-test; Figure 3B). Normalized power spectrum analysis
of another EEG signal epoch also showed a similar result (Figure
3C). The results indicated that mice showed different brain ac-
tivities toward cadaveric and anesthetized conspecifics and can
distinguish live from dead bodies.
Discussion
In the wild, animals may frequently encounter dead bodies and
observe the death of their family members. These experiences,
together with education from family or social groups, may help
animals understand or become aware of death and may cause
them to exhibit specific behavioral responses to the dead (or to
react differently to dead bodies), such as remaining near or car-
rying the deceased conspecific, as well as vocalizations, groom-
ing, or licking [2-6].
Death-related behavior in primates has been reported in several
studies [27-31]. For example, a daughter chimpanzee was re-
ported to groom and stay with her mother’s body, and to sleep
fitfully, for a few days after her mother’s death [32]. In addition,
elephants reportedly have a generalized response to a dead
body or death [33-35]. Elephants gather around a dead conspe-
cific, manipulate the body with their feet and trunks, and often
stand vigil for several days, which may indicate their awareness
of death [33]. Numerous reports have been published of
death-related behavior in other animals, such as giraffes [36],
dogs [37], and whales or dolphins [38,39]. Thus, animals, specif-
ically social mammalian species, can distinguish between life
and death; however, what a dead body signifies to these animals
is unknown.
In the present study, the effects of a dead body on a laboratory
mouse that has never previously encountered a dead conspecif-
ic and likely has not received any education regarding death
Daejong Jeon et al. Mouse responses to deceased conspecifics
encephalitisjournal.org encephalitis [Epub ahead of print] 5
from its family (parents or cagemates) were investigated. Expo-
sure to a cadaveric conspecific rendered mice more anxious
than exposure to an anesthetized conspecific. In the social in-
vestigation experiment, differences were not observed in con-
tact time between the cadaver and anesthesia groups on the first
day; however, differences were observed on the second and
third days. If mice had an innate fear of dead bodies, mice ex-
posed to a cadaveric conspecific should have exhibited reduced
contact time compared with mice exposed to an anesthetized
conspecific on the first day. The presence or smell of a predator
provokes immediate innate fear in rodents such as rats and
mice. Mice avoid the location of the predator, even when they
have never been exposed to it and have no prior learning expe-
rience [40]. However, on the second and third days, mice ex-
posed to the cadaveric conspecific displayed reduced contact
duration compared with mice exposed to an anesthetized con-
specific. Thus, initially the dead body was likely a novelty, and
source of curiosity, rather than a source of innate fear. Unlike ex-
posure to an anesthetized mouse, the odor from a dead body
can cause increased level of anxiety and locomotion and re-
duced contact duration.
Although difference was not observed in the contact duration
between the two groups on the first day, mice might have sus-
pected a problem with the cadaver and acquired some informa-
tion regarding the cadaver during the first investigation; they ex-
hibited different neural activities in the mPFC when investigat-
ing a cadaveric conspecific or an anesthetized conspecific in the
electrophysiological experiment. The mice may have learned to
fear or experienced anxiety from repeated exposure to cadaveric
conspecifics on the second and third days. However, the mice
may simply have lost interest more quickly in a body that was
dead compared with an alive but anesthetized body. In addi-
tion, whether the fear of a cadaveric conspecific in this study in-
cluded fear of mortality could not be determined [41,42]. Fur-
ther experiments are needed to determine whether exposure to
a cadaveric conspecific or exposure to potential death is recog-
nized as a fearful situation or source of anxiety in mice. In addi-
tion, further studies using familiar mice, such as cagemates or
siblings, as cadavers may significantly advance the understand-
ing of the neural basis of death-related behavior in animals.
In the present study, several experiments were performed to de-
termine how exposure to a cadaveric conspecific affects labora-
tory mice and what relevance it has. Notably, exposure to the
cadaveric conspecific rendered laboratory mice fearful or anx-
ious, and changed their brain activities. Encountering the dead
body of a conspecific may be a traumatic experience for labora-
tory mice and they may acquire fear of a cadaver without expe-
riencing an innate fear of death. Finally, the results indicated
that laboratory mice can learn about death through fear or anxi-
ety induced by exposure to a cadaveric conspecific. Although
whether laboratory mice learned or became aware of death
through investigation of a cadaver conspecific is unknown, ex-
periments using animal cadaveric conspecifics may provide in-
formation and facilitate further studies of brain disorders such
as suicidality and psychosocial behaviors.
Figure 3 Differences in brain oscillations of mice exposed to a
cadaveric mouse target and to an anesthetized mouse target
A
B
C
Anesthetized target
Cadaver target
0.2 mV
1 sec
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Normalized EEG powerNormalized EEG power
Delta
Delta
Theta
Theta
Alpha
Alpha
Beta
Beta
Gamma
Gamma
■ Anesthetized target
■ Cadaver target
■ Anesthetized target
■ Cadaver target
*
*
*
**
*
*
(A) Sample traces of electroencephalographic (EEG) signals from mouse medial
prefrontal cortex neurons during investigations of the cadaveric and anesthetized
mouse targets. (B, C) Power spectra analyses of two epochs of EEG signal: power
spectra analyses revealed that mice showed increased delta-band activity and
reduced theta- and alpha-band activities when they explored a cadaveric mouse
target than when they explored an anesthetized mouse target.
Comparison between the two targets in each band: *p < 0.05, **p < 0.01; Stu-
dent t-test.
encephalitisjournal.org
Daejong Jeon et al. Mouse responses to deceased conspecifics
6encephalitis [Epub ahead of print]
Conflicts of Interest
Daejong Jeon has been an associate editor of encephalitis since
October 2020. Sang Kun Lee and Kon Chu have been on the edi-
torial board of encephalitis since October 2020. They were not
involved in the review process of this original article. No other
potential conflict of interest relevant to this article was reported.
Author Contributions
Conceptualization, Methodology: Jeon D, Lee SK, Chu K; Inves-
tigation, Data curation, Formal analysis: Jeon D, Kim S; Resourc-
es: Lee SK, Chu K; Funding acquisition: Jeon D, Lee SK, Chu K;
Writing–original draft: Jeon D; Writing–review and editing: all
authors.
Acknowledgments
We would like to thank Ah Reum Yang (Laboratory for Neu-
rotherapeutics, Department of Neurology, Biomedical Research
Institute, Seoul National University Hospital, Seoul, Korea) for
her help in the behavioral tests. This work was supported by Ko-
rea Health 21 R&D grants (HI12C0035) funded by Ministry of
Health and Welfare and supported by a grant from Advanced
Neural Technologies (0620182930).
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