Life Science, Tokyo Gakugei University
Research group for Brain & Behavior

Hara Lab


            PI: Kenji Hara, e-mail: khara [at]      

Early in adult life animals receive input from the environment that shapes their behavior and neuronal connectivity. Environmental stimulation elicits various plastic responses in the brain, ranging from biochemical parameters to dendritic arborization, gliogenesis, or neurogenesis, resulting in improved learning abilities. The process through which an individual learns to respond to stimuli to which it is exposed during an early post-natal period has become an important paradigm for the study of the neural mechanisms of learning and memory.

In ants as in most social insects the first days after the emergence of the adult insect seem crucial for the integration and the socialization of individuals into their maternal colony. Newly emerged workers must learn nestmate recognition cues which are referred to as a sensory template (memory). This template is assumed to be involved in comparing individuals that are encountered and in determining their colony membership. The chemical signals mediating the nestmate discrimination are relative proportions of cuticular hydrocarbons, which are colony-specific and shared by all members of a colony. Therefore the olfactory system of ants should have the ability to process and learn the subtle differences in colony-specific odorant mixtures.

   The neuronal correlations with early learning of nestmate discrimination cues and the search for factors and mechanisms by which these processes are regulated are not known and pose challenging questions. Because many of the cellular and molecular mechanisms underlying neural plasticity appear to be common across different invertebrate taxa and even between insects and vertebrates, studies of neuronal mechanisms underlying ant nestmate discrimination are of broad significance. To address the functional significance of particular brain regions for the nestmate recognition ability, we have undertaken to analyze the structural modification in the brain of young worker during the familiarization period with nestmates of the carpenter ant Camponotus japonicus.

(Representive publications)

Kenji Hara (2002) A sensitve and reliable assay for queen discrimination ability in laboratory-reared workers of the ant Camponotus japonicus. Zool. Sci. 19:1019-1025.
Kenji Hara (2003) Queen discrimination ability of ant workers (Camponotus japonicus) coincides with brain maturation. Brain Behav. Evol. 62: 56-64.

Yuri Ishii, Kanae Kubota and Kenji Hara (2005) Postembryonic development of the mushroom bodies in the ant, Camponotus japonicus. Zool. Sci. 22: 743-753.

Michie Nemoto and Kenji Hara (2007) Ecdysone receptor expression in developing and adult mushroom bodies of the ant Camponotus japonicus. Dev. Genes Evol. 217: 619-627.

Natsume Nasu and Kenji Hara (2012) Gliogenesis in the mushroom body of the carpenter ant, Camponotus japonicus. Zool. Sci. 29: 800-806.

Kenji Hara (2013) Social association brings out the altruism in an ant. In: Witzany G (ed) Biocommunication of Animals. Springer, Capter9, 149-160....