[2] While a student at Kyoto University, Tonegawa became fascinated with operon theory after reading papers by François Jacob and Jacques Monod, whom he credits in part for inspiring his interest in molecular biology.

Tonegawa resigned his directorship in 2006 and currently serves as a Picower Professor of Neuroscience and Biology and a Howard Hughes Medical Institute Investigator.

Tonegawa's Nobel Prize work elucidated the genetic mechanism of the adaptive immune system, which had been the central question of immunology for over 100 years.

[5] Tonegawa was an early adopter of optogenetics and biotechnology in neuroscience research, leading to his groundbreaking work identifying and manipulating memory engram cells.

In 2012, his lab demonstrated that the activation of a specific sub-population of mouse hippocampal neurons, labelled during a fear conditioning paradigm, is sufficient to evoke a behavioral response correlated with a precise memory trace.

[6] More recently, his lab continues to employ optogenetic technology and virus injection techniques to expand their findings on the engram cell ensemble.