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Neurobiology of aggression

開催日 2014/9/11
時間 17:00 - 19:00
会場 Room A(Main Hall)
Chairperson(s) 岡本 仁 / Hitoshi Okamoto (理化学研究所 脳科学総合研究センター / RIKEN Brain Science Institute, Japan)

Evolutionarily conserved role of the habenula in control of self-conficence in aggression

  • S1-A-2-4
  • 岡本 仁 / Hitoshi Okamoto:1 
  • 1:理化学研究所 / RIKEN Brain Science Institute, Japan 

Aggression is an evolutionarily conserved behavior. During animal conflicts, experiences influence the outcome of contests such that previous winning experience increases the probability of winning a subsequent interaction, whereas previous losing experience has the contrary effect. Zebrafish have been used as a model animal for developmental biology and genetic study. They also exhibit aggressive behaviors and winner-loser effects. We previously showed that silencing of the neural pathway from the lateral subnucleus of the dorsal habenula (dHbL) to the dorsal interpeduncular nucleus (dIPN) caused a failure of acclimating behavioral responses by the dHbL-silenced fish from freezing to flight when they experienced repeated electric shocks paired with the conditioned stimuli. As different parts of PAG are responsible for evoking different ways of coping with aversive stimuli, such as flight, freeze and fight, we reasoned that this pathway may be involved in the re-evaluation of stimuli and modulates the switching of freezing and flight behavior. When animals encounter the opponents, each individual must evaluate the strength of the opponent and calculate the cost and benefit of fighting to make a proper decision to continue fighting or to surrender to escape from the conflicts. Taking the possible involvement of the habenula in re-evaluation of the aversive stimuli, we hypothesized that the habenula may integrate and evaluate the positive and negative information of conflicts and choose the proper behavioral reactions in animal fighting. Indeed the dHbL-silenced fish showed the higher tendency to lose when they fought with their control siblings due to the failure to accumulate the capacity to enhance the aggressiveness in a manner dependent on the accumulated experiences of dominance during fight (i.e. confidences) rather than their simple weakness in physical fitness. This failure of confidence accumulation also impaired the winner effect in the dHbL-silenced fish. Our findings suggest the dHbL-dIPN circuit is involved in re-evaluation of the strength of the opponents to accumulate the confidence of fighting experiences and ultimately generate the winner effect during zebrafish fighting. We are now accumulating the evidence that the role of Hb in regulation of aggression is conserved between fish and mammals.

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