Experimental evidence for sex-specific plasticity in adult brain

Background: Plasticity in brain size and the size of different brain regions during early ontogeny is known from many vertebrate taxa, but less is known about plasticity in the brains of adults. In contrast to mammals and birds, most parts of a fish’s brain continue to undergo neurogenesis throughout adulthood, making lifelong plasticity in brain size possible. We tested whether maturing adult three-spined sticklebacks (Gasterosteus aculeatus) reared in a stimulus-poor environment exhibited brain plasticity in response to environmental enrichment, and whether these responses were sex-specific, thus altering the degree of sexual size dimorphism in the brain. Results: Relative sizes of total brain and bulbus olfactorius showed sex-specific responses to treatment: males developed larger brains but smaller bulbi olfactorii than females in the enriched treatment. Hence, the degree of sexual size dimorphism (SSD) in relative brain size and the relative size of the bulbus olfactorius was found...背景：众多脊椎动物类群中，早期个体发育阶段的脑尺寸及不同脑区尺寸的可塑性已被广泛证实，但针对成体脑可塑性的相关研究仍相对匮乏。与哺乳类和鸟类不同，鱼类脑的绝大多数区域在成年后仍可持续进行神经发生，这使得脑尺寸的终身可塑性成为可能。本研究针对饲养于低刺激环境中的成熟成年三棘刺鱼（Gasterosteus aculeatus），探究其在环境富集条件下是否会表现出脑可塑性，以及该响应是否具有性别特异性，进而改变脑内的性大小二态性程度。结果：全脑与嗅球（bulbus olfactorius）的相对尺寸对处理条件呈现出性别特异性响应：在环境富集处理组中，雄性个体的全脑尺寸更大，但嗅球尺寸却小于雌性个体。因此，本研究发现全脑相对尺寸与嗅球相对尺寸的性大小二态性（SSD）程度存在……