RESEARCH ARTICLE◥

NEUROSCIENCE

History of winning remodelsthalamo-PFC circuit to reinforcesocial dominanceTingting Zhou,1,2,3,4* Hong Zhu,1,2,3,4* Zhengxiao Fan,3,4 Fei Wang,1,2 Yang Chen,1

Hexing Liang,3,4 Zhongfei Yang,1 Lu Zhang,5 Longnian Lin,6 Yang Zhan,7

Zheng Wang,1 Hailan Hu3,4,8†

Mental strength and history of winning play an important role in the determination of socialdominance. However, the neural circuits mediating these intrinsic and extrinsic factorshave remained unclear. Working in mice, we identified a dorsomedial prefrontal cortex(dmPFC) neural population showing “effort”-related firing during moment-to-momentcompetition in the dominance tube test. Activation or inhibition of the dmPFC inducesinstant winning or losing, respectively. In vivo optogenetic-based long-term potentiationand depression experiments establish that the mediodorsal thalamic input to the dmPFCmediates long-lasting changes in the social dominance status that are affected by historyof winning. The same neural circuit also underlies transfer of dominance between differentsocial contests. These results provide a framework for understanding the circuit basis ofadaptive and pathological social behaviors.

In most social species, reaching the top of thesocial hierarchy is strongly affected by mentalstrength or personality traits (including cour-age, perseverance, and motivational drive), aswell as a previous history of winning (1–6).

The formation of a dominance hierarchy canresult from a reinforcing mechanism known asthe “winner effect,”where animals increase theirprobability of victory after prior winning (7–11).The dorsomedial prefrontal cortex (dmPFC) hasbeen implicated in the chronic regulation of socialdominance (12–18). However, the acute require-ment of the dmPFC during ongoing social com-petition and the upstream neural circuits thatregulate dmPFC activity in dominance behav-iors have been essentially unknown. It has alsobeen unclear whether the winner effect can begeneralized—in other words, whether dominanceacquired in one type of competition can transferto another behavioral type.

Winner mice display more pushes andresistances in the dominance tube testTo investigate social competition in laboratorymice, we applied the dominance tube test (19),which is highly transitive and stable and cor-relates well with other dominance measures(6). The behavior in the tube test was video-monitored and categorized as push initiation,push-back, resistance, retreat, or stillness (Fig. 1,A and B; fig. S1A; movie S1; and methods).Analysis of 72 tube test trials revealed that win-ner mice initiated significantly more pushes, andwith a longer duration per push, than losermice(Fig. 1C). When being pushed, winner mice alsoshowed more and longer push-backs and resist-ances and fewer retreats (Fig. 1, D to F). For acage of four male weight-matched C57BL/6Jmice, we derived a linear dominance rank orderbased on total numbers ofwins against cagematesin pairwise tube tests (18) (fig. S1B). Opponentswithcloser rank distances spent a longer time and gen-erated more pushes (fig. S1, C and D) in the tube.

dmPFC neurons activated in effortfulbehavioral epochs during social contests

We performed single-unit recordings in freelybehaving mice while they engaged in the tubetest (Fig. 1G). Using 16-channel tetrodes targetingdmPFC [including the anterior part of the anteriorcingulate (ACC) and the prelimbic (PL) part of thePFC (fig. S2, A and B)], we successfully recorded342 well-isolated neurons in 22mice, including306 putative pyramidal (pPyr, 89.5%) and 36putative fast-spiking interneuron (pIN) cells (fig.S2, C and D; criteria for single-unit isolation andcell-type classification are given in the methods).

We aligned spiking activity with epochs of push-ing (including push initiation and push-back),resistance, retreat, and stillness (Fig. 1H andmeth-ods). The average firing rate of recorded pPyrunits was significantly higher during the “effort-ful” (push and resistance) behavioral epochs, butnot the passive (retreat) behavioral epochs, thanduring stillness (Fig. 1, H and I, andmovie S2). Incontrast, the average firing rate of pIN units in-creased insignificantly during the retreat epoch(Fig. 1J). A notable fraction of the pPyr units showedincreased firing rates during push (11.4%, 31 of271 units) and resistance (10.1%, 25 of 247 units)behaviors, significantly more than the fraction thatshoweddecreased firing rates (1.1% for pushing,P<0.0001, Z test; 2% for resistance, P = 0.002, Z test;Fig. 1K and fig. S2E). One-third of neurons (11 of 31)with increased activity during push behavior alsoshowed an increase in firing rate during resistance,which was significantly higher than the chancelevel (P< 0.0001, Z test; Fig. 1L). These 11 neuronsshowed highly correlated increases in activity dur-ing push and resistance behaviors [linear regres-sion analysis, coefficient of determination (R2) =0.82, slope = 0.90, P < 0.001; Fig. 1M]. Althoughboth pushing and resistance require effort, theydiffer in that the former involves bodymovement,whereas the latter does not. Thus, regardless ofwhether the animal is in motion, these two dif-ferent behavioral states tend to recruit the samesubset of dmPFC neurons.

DREADD inhibition of dmPFC reduceseffortful behaviors and causes losing

Given that dmPFC neuronal activity is differen-tially modulatedwhen animalsmake an effort dur-ing competition, we next testedwhether dmPFCneural activity is required for dominance in thetube test. We applied the DREADD (designer re-ceptors exclusively activated by designer drugs)method to inactivate dmPFC neurons, using anadeno-associated virus (AAV2) expressing the engi-neered Gi-coupled hM4D receptor (20) (Fig. 2Aand fig. S3, A and B). Whole-cell recordings ofneurons from acutely isolated dmPFC brain slicesconfirmed that clozapine-N-oxide (CNO, 5 mM)suppressedhM4D-expressingdmPFCneuron activ-ity (Fig. 2B), causing a significantly increasedspike threshold and decreased spike numberunder current step injections (Fig. 2, C andD).Wethen intraperitoneally (i.p.) injected CNO (5 mgper kilogram of bodyweight) into a subset ofmice(each from a different four-mouse group), whichhad hM4D expressed bilaterally in the dmPFCand had stable tube test ranks (persisting for atleast three continuous daily trials before the ma-nipulation; Fig. 2E). This treatment induced a de-cline in tube test ranks of the injectedmice, startingat 1 to 1.5 hours and peaking at 6 to 8 hours afterinjection (Fig. 2, E to G and fig. S3C). There weresignificantly fewer and shorter initiated pushesand push-backs, and more retreats, after CNOinjection (Fig. 2, H and I). At 24 hours after CNOinjection, most mice returned to their originalrank position (Fig. 2, E to G), consistent with thereversal of the effect on cell physiology after CNOwashout (Fig. 2B).

RESEARCH

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 1 of 7

1Institute of Neuroscience and State Key Laboratory ofNeuroscience, Shanghai Institutes for Biological Sciences,Chinese Academy of Sciences, Shanghai 200031, P.R. China.2Graduate School of Chinese Academy of Sciences, Shanghai200031, P.R. China. 3Interdisciplinary Institute of Neuroscienceand Technology, Qiushi Academy for Advanced Studies,Zhejiang University, Hangzhou 310012, P.R. China. 4Centerfor Neuroscience, Key Laboratory of Medical Neurobiologyof the Ministry of Health of China, School of Medicine, ZhejiangUniversity, Hangzhou 310058, P.R. China. 5Shanghai Centerfor Mathematical Sciences, Fudan University, Shanghai 200433,P.R. China. 6Key Laboratory of Brain Functional Genomics, EastChina Normal University, Shanghai 200062, P.R. China. 7BrainCognition and Brain Disease Institute, Shenzhen Institute ofAdvanced Technology, Chinese Academy of Sciences, Shenzhen518055, P.R. China. 8Mental Health Center, School of Medicine,Zhejiang University, Hangzhou 310013, P.R. China.*These authors contributed equally to this work.†Corresponding author. Email: huhailan@zju.edu.cn

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Optogenetic activation of dmPFCinduces instantaneous winning in thetube testUsing optogenetics, we next tested whether dmPFCactivation is sufficient to quickly induce domi-nance behavior in social competition. AAV2 virusexpressing light-sensitive channelrhodopsin (ChR2)(21) under the control of the ubiquitously expressed

CAG promoter (AAV-CAG-ChR2-tdTomato) wasstereotactically injected into the right dmPFC ofthe ranked mice and expressed for 4 weeks,and an optic fiber was implanted directly abovethe injection site (Fig. 3, A and B; fig. S4; andmethods). dmPFC neurons show both phasic andtonic firing patterns (22). We thus first used a100-Hz phasic protocol (9.9 ms per pulse, four

pulses per second; fig. S5A) with 473-nm laserstimulation, which significantly increased theexpression of the immediate early gene c-Fos inthe illuminated side of the dmPFC (P < 0.05;Fig. 3B). Whole-cell recordings in dmPFC brainslices showed that both a 100-Hz phasic protocoland a 5-Hz tonic protocol (fig. S5B) efficientlyactivated dmPFC neurons (Fig. 3, C and D), and

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 2 of 7

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Fig. 1. dmPFC neurons are activated during effortful behaviors in thedominance tube test. (A) Schematic of “effortful” (push initiation, push-back, and resistance) and passive (stillness and retreat) behavior patterns oftwo mice confronting each other in the tube test.The arrows indicate thedirection of body movement. (B) Sample behavior annotations for a pair ofmice in a tube test trial. (C and D) Number and mean duration of pushesinitiated (C) and push-backs (D).The number of trials is indicated in each bar.Mann-Whitney U test. (E and F) Percentage of time that mice resisted (E) orretreated (F) while being pushed. Mann-Whitney U test. (G) Tetrode recordingin the dmPFC of mice during the tube test (top) and three well-isolated singleunits (yellow, red, and blue clusters; bottom). PC, principal component.(H) Sample raster plots of a pPyr neuron during five losing tube test trials.Different behavioral epochs are indicated by colored shading. Inset,mean firingrate (FR) for different behavioral epochs. Kruskal-Wallis test. (I and J) Meanfiring rate of all pPyr (n = 160) (I) and pIN (n = 13) (J) units during different

behavioral epochs.One-way repeatedmeasures ANOVA (analysis of variance).(K) Scatter plots of the firing rates of all pPyr units during push (left),resistance (middle), and retreat (right) behavioral epochs, plotted against firingrates during the stillness epoch. Colored circles indicate neurons that showedsignificant differences in firing rates. Most of the circles are distributedunderneath the y = x diagonal line in the push and resistance plots, but not inthe retreat plot. Pie graphs show the percentage of pPyr neurons that hadsignificantly higher, significantly lower, or unchanged firing rates during therespective epochs, relative to stillness.Wilcoxon signed-rank test. (L) Venndiagram of overlap between subpopulations with increased activity duringpush, resistance, and retreat behaviors. (M) Linear regression analysis of thechange index (CI; see methods) of push and resistance behaviors for the11 neurons that showed significantly increased activity during both states.Dashed lines indicate 95% confidence intervals. *P < 0.05; **P < 0.01; ***P <0.001; ****P < 0.0001; n.s., not significant. Error bars, SEM.

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this was also verified by in vivo optrode record-ings of the single-unit responses from virallyinjected animals (Fig. 3, E and F).In tube tests with pairs of mice, we delivered

the 100-Hz phasic light protocol to one of themice to activate its dmPFC immediately beforeit entered the tube to confront its opponent, andwe kept the light on throughout the test, whichlasted, on average, 12.8 ± 1.3 s (n = 93; Fig. 3G).This instantaneously induced winning againstpreviously dominant opponents with a 90% suc-cess rate (Fig. 3, G and H; fig. S5C, J and K; andmovie S3), without affecting themotor perform-ance or anxiety level (fig. S6). The same photo-stimulation protocol did not affect the tube test

rank of mice injected with AAV-Ubi-eGFP virus(eGFP, enhanced green fluorescent protein) inthe dmPFC (Fig. 3I and fig. S5F). The 5-Hz tonicstimulation protocol had a similar success rate(80%) in elevating the rank of stimulated mice(Fig. 3J and fig. S5, D, J, and K).Under photostimulation, the originally sub-

ordinate mice not only resisted pushes from theopponents for a longer duration, but also pushedmore (Fig. 3K). The laser intensity required todominate the opponents correlated with the rankdistance that the mouse needed to move: A rankincrease of three (rank 4 moving to rank 1) re-quired laser intensity that was 3.2-fold that re-quired for a rank increase of two (rank 4 to rank

2 or rank 3 to rank 1) and 7.1-fold that requiredfor a rank increase of one (rank 4 to rank 3, rank3 to rank 2, or rank 2 to rank 1), demonstrating adosage-dependent relationship between the levelof dmPFC activation and the amount of effortrequired (Fig. 3L).Importantly, dmPFC photoactivation did not

changemuscle strength, as assessed bymeasuringgrip strength during the light-on and -off periods(fig. S7A). Most (98%, n = 103) photostimulatedtube test wins occurred within less than 1 min,suggesting that testosterone, a conventionallyslow-acting hormone, is unlikely to have playeda role in this quick process. To confirm this, wemeasured the levels of testosterone at 1 min and

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 3 of 7

Fig. 2. DREADD inhibition of dmPFC neurons causes losing anddecreases effortful behaviors in the tube test. (A) AAV-hSyn-hM4Dconstruct and viral injection site in the dmPFC, including the PL region andpart of the ACC. Scale bar, 50 mm. IRES, internal ribosome entry site; WPRE,woodchuck hepatitis virus posttranscriptional regulatory element; pA, poly(A);MO, medial orbital cortex. (B) Current-voltage relationship of a representativedmPFC neuron recorded before, during, and after 5 mM CNO perfusion. Rawtraces show individual voltage responses to a series of 600-ms current pulsesfrom 0 to 120 pAwith 20-pA steps. Red traces indicate the minimal current toinduce action potentials. (C) The minimal injected current to induce action

potential (APs) is increased byCNO. Paired t test, n= 10. (D) Number of inducedaction potentials at different current steps. Paired t test, n = 10. (E) Tube testresults for a cage of hM4D-expressing mice before and after i.p. injection ofCNO into the rank-1 mouse at time 0. hr, hour. (F) Summary of rank changes inhM4D-expressing mice after i.p. injection of CNO. Each line represents oneanimal. (G) Average rank change after CNO or saline injection.Wilcoxonmatched-pairs signed-rank test. (H) Behavioral annotation of two tube test trialsbetween the same pair of mice before and after CNO injection. (I) Comparisonof behavioral performance of same mice injected with saline solution or CNO.Mann-Whitney U-test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars, SEM.

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1.5 hours after photostimulation and found themto be indistinguishable from the baseline and un-stimulated control levels (fig. S7B). To test whetherthe increaseddominance ismanifestedby aheight-ened level of basal aggression, we subjected miceto the resident-intruder assay (23), during whichwe intermittently turned the 473-nm light (5 Hz,10ms) on and off in 1-min epochs with a switchedsequence. The test mice showed low basal ag-

gression levels and no significant differencebetween the light-on and -off periods in aggres-sive behaviors (including attacks and chases;fig. S7, C to F, and movie S4). Furthermore, thedmPFC-photostimulatedmice also showed a nor-mal preference toward novel mice in the socialmemory test (fig. S7, G and H).With localized injection, we mapped the effec-

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anterior part of the ACC and the PL region(Figs. 2A and 3A and fig. S4). Amore dorsal andposterior part of the ACC (Fig. 3M and fig. S8, Aand B) and a ventral mPFC site mostly contain-ing the infralimbic cortex (Fig. 3M and fig. S8,C and D) were not effective in stimulatingwinningbehavior (Fig. 3M and fig. S5, G and H). For cell-type specificity, we used a CaMKII (calcium- andcalmodulin-dependent protein kinase II) promoter

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 4 of 7

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Fig. 3. Optogenetic activation of dmPFC Pyr neurons induces instantwinning and more effortful behaviors in the tube test. (A) Schematicillustrating the CAG::ChR2 viral construct, viral injection site, and opticfiber placement (indicated by the white arrowhead). Scale bar, 100 mm.(B) c-Fos expression induced by photostimulation (NeuN, neuron nuclei).Scale bar, 50 mm. Student’s t test. (C and D) Current-clamp traces froman in vitro slice recording of a ChR2-expressing neuron illuminated by100-Hz phasic (C) or 5-Hz tonic (D) light stimulation. Scale bars in (C),100 ms (horizontal) and 20 mV (vertical); in (D), 1 s and 40 mV. (E andF) Raster plots (top), peristimulus time histogram (middle), and waveform(inset; scale bars, 500 ms and 50 mV) from an in vivo optrode recordingof a single neuron responding to 100-Hz phasic (E) and 5-Hz tonic (F)light stimulation. The Z-scored single-unit firing rates of multiple neuronsare shown in the bottom panels. (G) Daily tube test results for a cage ofmice injected with CAG::ChR2 virus before and after acute dmPFC

photostimulation of the rank-3 mouse at day 0. (H and I) Summaryof dmPFC photostimulation–induced rank change in mice injectedwith CAG::ChR2 (H) or Ubi::eGFP (I) virus. Each line represents oneanimal. (J) Rank change in the tube test under different stimulationconditions. Light stimulation was delivered throughout the tube test atday 0. Wilcoxon matched-pairs signed-rank test. Except as noted,CAG-ChR2 mice were used. (K) Comparison of the behavioral perform-ances of same mice during light-off and light-on trials. Mann-WhitneyU test. (L) A greater rise in rank position requires a stronger laserintensity. Wilcoxon signed-rank test. (M) Left, schematic illustratingmPFC subregions. The dmPFC contains both anterior ACC and the PLregion. IL, infralimbic; pACC, posterior ACC. Right, rank change in thetube test after optogenetic activation of different mPFC subregions.Wilcoxon matched-pairs signed-rank test. *P < 0.05; **P < 0.01; ***P <0.001. Error bars, SEM.

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to drive ChR2 only in dmPFC Pyr neurons, and wefound that it was sufficient to elevate tube test rank(Fig. 3J and fig. S5, I to K).

Synaptic strength in the MDT-dmPFCcircuit underlies the winner effectin the tube test

Performance in the tube test diverged on thesecond day after photostimulation: Some micereturned to their original rank, whereas othersmaintained their newly elevated rank (Fig. 3Hand 4A). Comparison of their experiences revealedthat thesemice differed in the number of winningtrials on the stimulation day:Mice receivingmorethan six photostimulated wins all maintainedtheir new rank, whereas most mice receivingfewer than five photostimulated wins returnedto their original rank (Fig. 4A). This sustainedrank elevation was not caused by a secondaryeffect through the experience of nonstimulatedrival mice (fig. S9). Thus, repeated stimulatedwinning led to sustained dominance withoutfurther photostimulation, reflecting the winnereffect. Systematic injection of MK801 (0.15 mg/kg, i.p.) eliminated the sustained winning in-duced by six photostimulated wins, suggestingthat an NMDAR (N-methyl-D-aspartate receptor)–dependent plasticity mechanism may mediatethis long-lasting increase in dominance (Fig. 4Band fig. S10A).We next searched for the neural circuit path-

way that supports this behavioral plasticitymecha-nism. The mPFC receives prominent projectionsfrom the mediodorsal thalamus (MDT) (24), andtheMDT-dmPFC circuit shows synaptic weaken-ingduring repeated defeat–induced social avoidance(25). We thus hypothesized that this same pathwaymay undergo long-lasting synaptic strengtheningafter repeated winning. If that is the case, weshould be able to (i) detect enhanced synapticstrength in the MDT-dmPFC pathway after re-peated winning, (ii) eliminate the sustained win-ning by introducing long-term depression (LTD)to reverse the synaptic strengthening in theMDT-mPFC circuit, and (iii) directly cause sustainedwinning by inducing long-term potentiation (LTP)in the MDT-mPFC synapses without any tubetest competition. We expressed oCHIEF, a var-iant of ChR2 that can faithfully respond to 100-Hzstimulation (fig. S11A) (26, 27), in the MDT (fig.S12, A to C) and implanted an optrode (for elec-trophysiology recording) or an optic fiber (forbehavioral manipulation) in the dmPFC (Fig. 4C;fig. S12, D and E; and methods). Optical activa-tion of the MDT axonal terminals in the dmPFC(5 Hz, 10 ms) induced instantaneous winning inthe tube test (fig. S12F).To measure synaptic responses of the MDT-

dmPFC pathway in free-moving mice, we recordedfield response in the dmPFC evoked by photo-stimulation of the oCHIEF-expressing MDT-dmPFC axonal terminals. Brief pulses of bluelight were delivered at 0.05 Hz through the opti-cal fiber, and fEPSPs (field excitatory postsynapticpotentials) were used tomeasure theMDT-dmPFCsynaptic efficacy (fig. S11, B and C) (27). After astable baseline was acquired for at least 3 days,

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 5 of 7

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Fig. 4. Synaptic strength of the MDT-dmPFC circuit underlies the winner effect in the tubetest. (A) Mice either maintain their new rank or return to their original rank position after dmPFCphotostimulation, depending on the number of stimulated-win trials. Z test, n = 13 and 11 mice thatunderwent two to five and six to 20 stimulation trials, respectively. d, day. (B) I.p. injection of MK801,but not saline solution, at 30 min before six photostimulated wins abolished sustained winning onsubsequent days. Left,Wilcoxon signed-rank test; right, Z test. (C) Optogenetic LTP or LTD experiment inthe MDT-dmPFC pathway.Top, schematic of viral injection and opotrode recording sites. Bottom left,representative coronal section showing the injection site of AAV-oCHIEF-tdTomato in MDT. Bottom right,representative coronal dmPFC section showing distribution of tdTomato+ axons projected from theMDT. LHb, lateral habenular; MHb, medial habenular; MDC, mediodorsal thalamus, central; MDM,mediodorsal thalamus, medial; MDL, mediodorsal thalamus, lateral. Blue, Hoechst; red, tdTomato.Scale bars, 25 mm (top right) and 500 mm (bottom right). (D) Average slopes of in vivo light-evokedfEPSPs (average of six responses) in the dmPFC (normalized to baseline) before and after six winsinduced by photostimulation of MDT-dmPFC terminals. Insets, representative fEPSP trace before andafter six wins. Paired t test. (E and G) Average slopes of in vivo light-evoked fEPSPs (average of sixresponses) in the dmPFC (normalized to baseline) before and after LFS (E) or HFS (G). Insets,representative fEPSP traces before and after LFS (E) and HFS (G). (F) LFS reverses the sustained rankincrease resulting from six wins induced by MDT-dmPFC photostimulation. Left,Wilcoxon signed-ranktest; right, Z test. (H) HFS induction directly causes sustained winning in the tube test. Left,Wilcoxonsigned-rank test; right, Z test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars, SEM.

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we photostimulated the MDT-dmPFC axonalterminals to induce repeated winning six timesand measured the fEPSPs on the following days.Accompanying the rank elevation, the fEPSP ofthe MDT-dmPFC pathway was significantly in-creased on the following 2 days after repeatedwinning, reflecting strengthening of the MDT-dmPFC synapses (Fig. 4D).Next, by applying low-frequency stimulation

(LFS), an optical LTD protocol (900 pulses of 2-mslight stimulation delivered at 1 Hz; fig. S11D)(27, 28), at theMDT-dmPFC terminals, we wereable to induce LTD in theMDT-dmPFC synapses(Fig. 4E) and eliminate the sustained winningeffect after six stimulated wins (Fig. 4F and fig.S10B). Conversely, delivery of high-frequencystimulation (HFS), an optical LTP protocol (fig.S11A and methods) (28), at the MDT-dmPFCterminals significantly potentiated MDT-dmPFCtransmission in vivo (Fig. 4G). Application of thisin vivo LTP protocol to freely moving mice in thehome cage caused significant, long-lasting tubetest rank increases (Fig. 4H and fig. S10C).

Transferrable winner effect from thetube test to the warm spot competitionWe next asked whether dominance acquired inthe tube tests can transfer to other forms of domi-nance behavior. We subjected mice to an inde-pendent measure of social hierarchy, the warmspot test, in which four cagemate C57 mice com-peted for a warm corner in a cage with an ice-cold floor (Fig. 5A). The amount of time that eachmouse occupied the warm spot correlated withits tube test rank (Fig. 5, B to D, and movie S5),cross-validating that these two assays sharedominance as a common core variable. Activationof dmPFC neurons by using AAV2 expressingthe engineered Gq-coupled hM3D receptor (20)increased the occupation time and rank in thewarm spot test at 2 hours, but not 2 days, afterCNO injection (1 mg/kg, i.p.) (Fig. 5, E and F).We then tested whether sustained winning in

the tube test resulting from repeated dmPFC stim-ulation could lead to increased rank in the warmspot test. After we subjected mice that were pre-viously subordinate in both tests to 10 photo-

stimulated tube test wins, their occupation timesand ranks in thewarm spot test were significantlyelevated compared with their performances be-fore the tube test (P = 0.016 for occupation time,P = 0.016 for rank, Wilcoxon signed-rank test;Fig. 5, G to I), even though these mice were notdirectly stimulated in the warm spot context.

Discussion

Collectively, these results provide strong evidencethat activation of the dmPFC is both necessaryand sufficient to quickly inducewinning in socialcompetitions. Specifically, by optogenetically isolat-ing a synaptic input from the MDT to the dmPFC,we could selectively manipulate synapses drivenby this input and establish a causal relationshipbetween the activity of theMDT-dmPFC circuitand dominance behavior. dmPFC activation doesnot seem to boost dominance by enhancing basalaggression level or physical strength (fig. S7), butrather by initiating andmaintainingmore effort-ful behaviors in social competition (Fig. 3K). ThemPFChas been implicated in cost-benefit analysis

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Fig. 5. Transferrable dominance from the tube test to the warm spotcompetition. (A) Schematic of the warm spot test. Four mice competefor a warm corner in a cage with an ice-cold floor. (B) Cumulative timein the warm spot of four cagemate mice of different tube test rank.Inset, total time in the warm spot in the 20-min test. (C) Correlationbetween time in the warm spot and tube test rank. Pearson’s correlationtest, P = 0.046. (D) Contingency table showing the correlation betweenrank in the tube test and rank in the warm spot test. The number ofanimals in each category is displayed. (E and F) Time in the warm spot(top) and rank in the warm spot test (bottom) for mice expressing hM3Din the dmPFC at 1 day before, 2 hours after, and 2 days after i.p. injectionof CNO (E) or saline solution (F). Data for each mouse are shown ingray; averages are shown in red and blue; n = 6. (G) Schematic of

the experimental procedure. After basal ranks were assessed in the tubetest and warm spot test, dmPFC photostimulation was applied tosubordinate mice during the tube test to induce winning in 10 successivetrials; mice were confirmed to maintain the elevated tube test rank inthe absence of photostimulation and then subjected to the warm spottest. The red asterisk marks the mouse being manipulated. (H) Timein the warm spot (left) and rank (right) in the warm spot test wereelevated 2 hours after repeated winning in the tube test. Wilcoxonmatched-pairs signed rank test, n = 6. (I) Rank increase in the warm spottest is specific to mice with a sustained rank increase in the tube test.Mann-Whitney U test. (J) Reciprocal reinforcement of winning in differentcontests leads to establishment of dominance hierarchy. *P < 0.05; **P <0.01. Error bars, SEM.

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and effort-based decision-making (14–16, 29–32).We propose that thesemPFC-based cognitive pro-cesses may provide a neurobiological foundationfor dominance-associated personality traits, suchas perseverance or competitive drive.One important parameter for the cost-benefit

computation in a social confrontation is the his-tory of winning. With the in vivo optogenetic LTPand LTD experiments, we provide evidence thatsynapses in the MDT-dmPFC pathway may en-code winning history. Whereas earlier work onthe winner effect in fish was mostly focused onhormonal changes after repeated winning (33),our results reveal that the synaptic plasticitymechanism in the MDT-dmPFC circuit plays akey role in the winner effect in mammals. More-over, we discovered a generalized form of thewinner effect, where dominance transfers fromone contest type to another through a sharedneural circuit mechanism. Previous studies ofthe winner effect were restricted to the impact ofwinning on the same behavior paradigm (33).However, given that animals are dealing withdifferent forms of competition in setting up thesocial hierarchy, the generalized winner effectthat we describe here is of high evolutionaryimportance—for example, it may allow amonkeythat succeeds in fighting for bananas earlier tooccupy a more comfortable resting spot later.Such reciprocal reinforcement between winningin different behavioral paradigms would help toaccelerate the establishment of a stable domi-nance hierarchy (Fig. 5J). It may also have im-portant implications in cognitive training forcompetitive games. Considering that an excessor lack of dominance drive is associatedwithmanypersonality disorders and mental problems, our

results might shed light on the treatment ofthese psychiatric diseases.

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ACKNOWLEDGMENTS

We thank Q. Li, H. Kessels, H. Li, and W. Li for critical comments onthe manuscript; D. Anderson for stimulating discussions that led tothe idea of the warm spot test; J. Zhu and K. Yuan for assistancein experiments; K. Deisseroth and Z. Qiu for AAV-ChR2 constructs;B. Roth for AAV-hM4D and AAV-hM3D constructs; C. Li and X. Gufor advice on analysis of tetrode recording data; and X. Xu forMatlab code for behavior annotation. This work was supported bygrants from the Ministry of Science and Technology of China(2011CBA00400 and 2016YFA0501000), the National NaturalScience Foundation of China (91432108, 31225010, and 81527901),and the Strategic Priority Research Program (B) of the ChineseAcademy of Sciences (XDB02030004) to H.H. All the datanecessary to understand and assess the conclusions of thismanuscript are available in the supplementary materials.Computer codes are archived at www.dropbox.com/sh/7pthozsrzj4vxr0/AACMaW9a8_5ITDumIJw_6Z_pa?dl=0. T.Z. andH.Z. conducted most optogenetic and behavioral experimentsand designed the experiments with H.H. T.Z. performed in vivotetrode recording with the help of Y.C. and Z.Y. and conductedoptogenetic LTP and LTD experiments. Z.F. performed the warmspot test and dominance transfer experiments. F.W. and H.L.participated in tube test and viral injection experiments. L.Z.,L.L., Y.Z., and Z.W. participated in analysis of in vivo tetroderecordings. H.H. conceived the project and wrote the manuscriptwith the help of T.Z. and H.Z.

SUPPLEMENTARY MATERIALS

www.sciencemag.org/content/357/6347/162/suppl/DC1Materials and MethodsFigs. S1 to S12Table S1References (34–51)Movies S1 to S5

18 February 2017; accepted 9 June 201710.1126/science.aak9726

Zhou et al., Science 357, 162–168 (2017) 14 July 2017 7 of 7

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History of winning remodels thalamo-PFC circuit to reinforce social dominance

Zhan, Zheng Wang and Hailan HuTingting Zhou, Hong Zhu, Zhengxiao Fan, Fei Wang, Yang Chen, Hexing Liang, Zhongfei Yang, Lu Zhang, Longnian Lin, Yang

DOI: 10.1126/science.aak9726 (6347), 162-168.357Science 

, this issue p. 162Sciencehistory.

based dominance behavior. Thus, synapses in this pathway store the memory of previous winning or losing−effort Selective manipulation of synapses driven by this input revealed a causal relationship between circuit activity and mental

is mediated by neuronal projections from the thalamus to a brain region called the dorsomedial prefrontal cortex. found that this effect et al.Social dominance in mice depends on their history of winning in social contests. Zhou

The brain circuits of a winner

ARTICLE TOOLS http://science.sciencemag.org/content/357/6347/162

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