[3] Cai finished his psychological training in California University during 1919–1921, then he entered University of Chicago as a postgraduate with Harvey A. Carr's guidance, he also focused on the subjects overlap psychology such as neuroanatomy and physiology during this period, and finally altered his research field towards the latter thenceforth.

Cai returned to China in 1925, and took a post of professor of physiology at Fudan University.

Cai went to the United Kingdom and Germany as a senior visit scholar within laboratory of C. Lovatt Evans, and later, Edgar Adrian from 1930–1932.

Cai moved to West China followed the university after the Marco Polo Bridge Incident.

Since the school moved to Xi'an, he went to Beijing and entered Academy of Military Medical Sciences (AMMS) in 1954 as vice president and chairman of Academic Council.