They combined conventional PETimaging, which requires a radioactive tracer to highlight the brain's metabolic activity, with other recent advances in the genetic engineering of brain cells that allows them to target specific brain circuits in lab animals.
In addition, Techniques like Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), and Magnetic Resonance Imaging (MRI) are going to unravel the mystery of the neuron jungle.