Susumu Tonegawa is interested in the brain mechanisms underlying learning and memory. Working in mice, Tonegawa and his team employ genetic engineering to study the role of gene products in specific neuron types and their circuits, especially for a defined period of a learning or memory process. Comparing engineered mice to standard control mice allows for detection and analysis of behavioral effects. The team seeks to understand what environmental information the brain extracts through experience and how it is stored in neurons and their network (memory engram). They have also been investigating how memory plays into emotion and how memory of past experiences is converted into knowledge supporting new learning.