Akihiro Kusumi has studied in Kyoto, where he returned to work in 2005. He proposed an explanation for reduced diffusion speed of lipid and protein molecules in the cell membrane, based on a model of hop diffusion in which lipids are confined to a reduced space, created by a membrane-skeleton-induced compartments. These compartments allow the lipids or proteins freely in a limited region and limiting also the diffusion to other parts of the membrane. Getting to a new compartment is called "hop diffusion" while diffusion in the compartment is allowed by Brownian movement, the compartments of the cell are responsible of the reduced diffusion speed of the lipid or proteins when compared to artificial vesicles. His love of biological membranes, particularly in the neuronal network, was accidentally initiated when he, a senior majoring in physics at that time, entered a wrong lecture room where Prof. Shun-ichi Ohnishi of Kyoto University happened to be lecturing about the Singer-Nicolson’s fluid mosaic model in his membrane course in 1974. Prof. Ohnishi became his PhD advisor, with whom he studied the rotational diffusion of rhodopsin in reconstituted membranes. He did his first postdoc with Prof. Jim Hyde of the Medical College of Wisconsin, who is responsible for his experimental physics (nonlinear EPR of membranes, 1980-2). He did his second postdoc with Prof. Malcolm Steinberg (Princeton University, 1982-4), who is responsible for his cellular and developmental biology.