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.