Can we edit the content of our memories? It’s a sci-fi-tinged question that Steve Ramirez and Xu Liu are asking in their lab at MIT. Essentially, the pair shoot a laser beam into the brain of a living mouse to activate and manipulate its memory. What are some of the implications of this technology, both for good and for harm.

Why you should listen:

Last year, MIT neuroscientists Xu Liu and Steve Ramirez manipulated the memory of a mouse. In a fascinating and mildly troubling breakthrough caused by a laser and the protein channelrhodopsin, they “activated” fear memories in a mouse.

Xu Liu received his Ph. D. from Baylor College of Medicine. During his Ph. D., he studied the mechanisms of learning and memory using fruit flies as a model system. By changing the expression of certain genes in the fly brain, he generated smart flies that can learn many times faster than their peers. Using live imaging, he also detected learning induced changes in the brain cells and observed memory formation inside the brain with light. He and colleague Rameriz are currently working with mice

Who are they:

Steve Ramirez aims to be a professor who runs a lab that plucks questions from the tree of science fiction to ground them in experimental reality. He believes that a team-oriented approach to science makes research and teaching far more exciting. When he’s not tinkering with memories in the lab, Ramirez also enjoys running and cheering on every sports team in the city of Boston.

Xu Liu moved to MIT and joined Dr. Susumu Tonegawa’s lab as a postdoctoral associate. He continued his pursuit of memory with light there. Instead of just watching memory formation, he developed a system in mice where one can not only identify and label cells in the brain for a particular memory, but also turn these cells on and off with light to activate this memory at will. This work was published in Science, and has been covered by the media worldwide, including The Boston Globe, Scientific American, The Daily Mail, and The Guardian.


  1. Rameriz opens the talk by telling of a recent breakup, which he wishes he could erase from his memory. Do you have any memories that you wish you could make go away?
  1. This pair of neuroscientists work with what species to explore how memory works?
  1. The process is as simple as finding a memory in the brain and turning it on or off with a switch. But it also much more complex. What two factors were used in their research? One biological, the other man-made?
  1. The light sensitive switch in the brain is A) xylocain or B) OxyContin or C)channelrhodopsinor D) phencyclidine.
  1. As a psychologist, would you like to have the ability to alter a patient’s memory of events they had lived through?
  1. In a discussion with your classmates tease out some of the ethical factors that are impacted by the possibilities the research foreshadows.

A mouse. A laser beam. A manipulated memory. with Steve Ramirez and Xu Liu


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