Research

I try to understand the human brain and intelligence by combining three different approaches. I further apply these technologies to the industry.

Serotonin regulation of brain-wide dynamics [Hamada et al., Nat Commu, 2024]

We investigated the brain-wide response of dorsal raphe serotonin neurons by optogenetic stimulation under awake mice with 11.7T high-resolution MRI.

Findings

We observed brain-wide positive response including reward-related circuits, which is replicated in another session.
We observed a brain-wide negative response under an anesthetized state consistent with a previous study.
The brain-wide BOLD response showed an association with the structural density of dorsal raphe serotonin projections.
Using mRNA maps of 5-HT receptors and structural density, we fit them to brain-wide response by optogenetic stimulation. The inhibitory 5-HT1 system showed negative weights while the excitatory 5-HT2 system showed positive weights. Furthermore, the weights of receptor systems may be different under anesthetized and awake states.

We will study how the serotonin system contributes to brain dynamics and cognitive tasks.

Hamada H.T.*, Abe Y., Takata N., Taira M, Tanaka F.K. and Doya K*. (2024) Optogenetic activation of dorsal raphe serotonin neurons induces brain-wide activation. Nat Commun 15, 4152. https://doi.org/10.1038/s41467-024-48489-6 [Preprint] [Tweets] [Dataset] [Codes]

Related research:

Hata, J., ...., Hamada, H.T. et al., (2023) Multi-modal brain magnetic resonance imaging database covering marmosets with a wide age range. Scientific Data 10, 221. https://doi.org/10.1101/2022.09.21.508952
Youssef, M., Hamada, H.T. et al., (2022) Tob1 is a key effector in hippocampal-mediated acute stress response. Translational Psychiatry 12, 302. https://doi.org/10.1038/s41398-022-02078-7
Abe, Y.*, Takata, N., Sakai, Y., Hamada, H.T., Hiraoka Y., Aida, T., Tanaka, K., Le Bihan, D., Doya, K., and Tanaka, K.F. (2020) Diffusion functional MRI reveals global brain network functional abnormalities driven by targeted local activity in a neuropsychiatric disease mouse model. NeuroImage. 223. https://doi.org/10.1016/j.neuroimage.2020.117318

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