To understand the behavior of whole circuits in the brain, neuroscientists want to monitor the activity of as many neurons as possible. To address this need we have developed a complete extracellular electrophysiology solution, including custom microfabricated multi-site silicon electrodes with low-impedance PEDOT polymer electrode coatings, a 256-channel low-noise multiplexed recording system, and open source data acquisition software. Building on this experience, we are spearheading an international effort, the Neuropixels Project, to enable large-scale brain recordings through the development of active electronic probes having several hundred sites per shank. This 3-year project brings Janelia together with the European consortium IMEC, the Allen Brain Institute, the Welcome Trust, the Gatsby Foundation, Oxford University, and University College London.
The standard tool for exploring characteristics of individual neurons is patch physiology. We have enhanced this technique by creating several novel probes: motion-tolerant patch pipettes, patch pipettes containing extracellular tri-electrodes enabling co-located intra- and extracellular recordings, and fluorescent patch pipettes for image-guided electrophysiology. We have developed novel multifunction optrode devices that combine light delivery (for target cell localization and/or optogenetic manipulation) with fluorescence collection, and additionally with conventional electrophysiology.