From Scalpel to Light · Episode 8 of 10 · 20 min
What the Light Revealed
Optogenetics became the most powerful tool for mapping the brain's wiring. In mice it showed how deep brain stimulation may work, traced circuits of reward and depression-like behavior, separated the brain's go and stop pathways, and reactivated single memories. The episode keeps the discipline the field requires: these are animal findings, two 2012 studies pointed opposite ways, and erasing trauma with light is science fiction.
Who's who
- Karl Deisseroth+3 more episodesStanford psychiatrist and bioengineer; senior author on much of this work
- Viviana Gradinaru+2 more episodesDeisseroth lab student who took deep brain stimulation apart with light
- Anatol KreitzerDrove the direct and indirect basal-ganglia pathways in mice
- Susumu TonegawaNobel laureate who turned to memory research at MIT
- Kay TyeLed amygdala anxiety and dopamine studies in the Deisseroth lab
- Joseph LeDouxCo-author of the 2010 study replacing a shock with light
- Gregory QuirkCo-author of the 2015 fear extinction study
- Michael FoxCo-author of the 2017 study linking stimulation site connections to outcomes
Where it happens
- Stanford University, California+8 more episodesHome of the Deisseroth lab
- Massachusetts Institute of Technology, CambridgeTonegawa's laboratory for engram studies
- Grenoble, France+1 more episodeWhere modern deep brain stimulation for tremor began
Timeline
- March 19, 2009Study shows deep brain stimulation's benefit tracks driving incoming fibers in rodents
- July 7, 2010Direct and indirect pathways driven separately in mice
- March 22, 2012Reactivating fear-learning cells makes mice freeze in a different place
- December 12, 2012Companion dopamine and depression papers point in opposite directions
- July 2013A false fear memory is implanted in mice
- June 17, 2019Measurements show routine optogenetic light heats tissue
Still debated
Whether the 2009 account is the whole story of deep brain stimulation in humans is still argued. The opposing 2013 dopamine results are reconciled only after the fact, and whether engram reactivation is memory retrieval or something adjacent is open. Rodent maps may not transfer to people.