Katsuyasu Sakurai

What is the purpose for all living things? If think thoroughly, all behaviors of human and other organisms aim to fulfill their desires to live. The ultimate goal of my research is to understand the neural mechanisms underlying the desires to live.

I focus on the two fundamental desires which are evolutionarily conserved in all organisms; desire for sex, and desire for sleep.

The biological purpose of sex is to transfer the genes to the next generation. In other words, the desire of sex is the desire for future life. In my view, the desire for sex may be fulfilled by achieving the “orgasm”, hence, the central question is: what is the neural representation of orgasm in the brain. In case of the male mouse, sex consists of a series of sequential behaviors: female recognition, chasing, mounting, intromission and ejaculation as the climax. It is often thought that ejaculation triggers orgasm or vice versa. Thus, we are in the process of identifying the neural ensemble that encodes orgasm using histological and imaging techniques. Afterwards, we will investigate the causality between the neural activity of the specific neural population and ejaculation/orgasm.

Furthermore, sexual activities increase sleep need. Thus, I’m interested in studying how sexual behaviors regulate sleep need. To address this question, I will focus on sexual satiety. It is known that several times of ejaculation induces post ejaculation refractory period and this condition would be the representation of sexual satiety. I speculate that sexual satiety would be the key phenomena for studying how sexual behaviors affect sleep need. I will attempt to reveal the neural basis of sexual satiety induced sleep changes.