Jin Hyung Lee1, Remy Durand2,
Viviana Gradinaru2, Feng Zhang2, Dae-Shik Kim3,
Karl Deisseroth2
1Electrical Engineering, University of
California, Los Angeles, Los Angeles, CA, United States; 2Bioengineering,
Stanford University, Stanford, CA, United States; 3Boston
University, Boston, MA, United States
Despite
an enormous, rapidly-growing functional brain imaging literature based on
blood oxygenation level dependent (BOLD) signals, it remains controversial
which classes of local activity and cellular elements (e.g., glia, axonal
tracts, or excitatory neurons) can trigger BOLD responses. Using a novel
methodology integrating Optogenetics with high-field fMRI, we show here that
robust BOLD signal can be triggered in primary motor cortex by specific
recruitment of CaMKIIa-expressing excitatory neurons. We further show that
this approach allows for highly specific in vivo circuit identification, in
which the functional role of cell types defined by location and genetic
identity, can be directly observed and globally mapped in the living mammal.