The role of the Island of Calleja in emotional behavior

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K07436
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 52020:Neurology-related
• Research Institution: Hiroshima University
• Principal Investigator: Matsumata Miho (酒寄美穂) 広島大学, 医系科学研究科(医), 助教 (50595460)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: カレハ島 / 嗅結節 / 側座核 / 意欲 / うつ病 / アンヘドニア

Outline of Final Research Achievements

The Islands of Calleja (ICj) are a group of neural cells that line the ventral part of the olfactory tubercle in the olfactory cortex, in a floating island-like pattern from rostral to caudal and from medial to lateral. In mice, because the ICj are located deep in the forebrain, and the number and size of islands have the large individual variations, it was difficult to physically manipulate the ICj. Therefore, we used transgenic mice in which Cre expression was specifically localized to the ICj, for histological analyses and behavioral changes induced by ICj activation. The ICj is mostly GABAergic granule cells, but cholinergic neurons and NOergic neurons were scattered around its periphery. Their projections extended toward the nucleus accumbens and the ventral surface of the ICj, a granule cells area. Furthermore, activation of the ICj granule neurons via optogenetic stimulation caused place preference among some of behavior analyses.

Free Research Field

神経科学

Academic Significance and Societal Importance of the Research Achievements

ICjはげっ歯類では腹側表面に一部が露呈しており目立つこともあって、古くから注目を浴び当時から研究は行われていた。しかし一方で個体差が激しく、また脳底へのアクセスの難しさからなかなか理解が進まず、役割についてもわかっていなかった。今回、ICjが関与すると思われるいくつかの行動の変異がマウス個体を用いた実験から明らかとなり、すでに知られていた神経基盤に加えてICjが新たな寄与神経核であることがわかった。本研究は抑うつ状態の中心症状である意欲や気力の減衰、アンヘドニアの神経基盤の理解を目指して立案しており、治療介入手法の選択肢を増やすという意味でも社会的意義があると考えられる。