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Learning and Long-term Memory

開催日 2014/9/11
時間 16:00 - 17:00
会場 Poster / Exhibition(Event Hall B)

Intermediate hyperpallium apicale , a dorsal posterior part of visual Wulst, is necessary for filial imprinting in domestic chicks

  • P1-268
  • 青木 直哉 / Naoya Aoki:1 山口 真二 / Shinji Yamaguchi:1 北島 孝明 / Takaaki Kitajima:1 松島 俊也 / Toshiya Matsushima:2 本間 光一 / Koichi J Homma:1 
  • 1:帝京大学・薬 / Sch Pharm Sci, Teikyo Univ, Tokyo, Japan 2:北海道大・院・生命科学 / Dept Biol, Fac Sci, Hokkaido Univ, Hokkaido, Japan 

Filial imprinting of domestic chicks is a useful model for early learning. In imprinting, the chick follows a moving object and then memorizes it after a series of the training, even it is inanimate. Imprinting has clear sensitive period which is from hatching to day 3. Our recent study showed thyroid hormone 3,5,3'-triiodothyronine (T3) plays critical roles for the start of the sensitive period. Even after the sensitive period closed, intravenous T3 injection enables the chick acquire imprinting. Furthermore, direct injection of T3 into an associative area IMM (intermediate medial mesopallium) which is necessary for imprinting recovers the sensitive period. The IMM has been intensively studied as a central neural mechanism for the imprinting. However, brain regions which are important as downstreams from IMM for imprinting is not known. In this study, we show IMHA (Intermediate hyperpallium apicaleplay), a dorsal posterior part of visual Wulst which is homologous to the primary visual cortex in mammals, plays important roles as a downstream from IMM. Bilateral ablation of IMHA prevented the acquisition of imprinting and the recovery of sensitive period induced by T3. But direct injection of T3 into IMHA could not enable the chick acquire imprinting, suggesting that IMHA alone is not sufficient for imprinting acquisition. On the other hand, IMHA-ablated chicks which were injected with T3 into IMM were not imprinted. Futhermore, by using an anterograde tracer WGA (wheat-germ agglutinin) which can transfer transsynaptically, the neural connections from IMM to IMHA were detected. These results suggest the IMHA receives T3 signaling from IMM and modulates it to acquire imprinting.

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