A transparent set of electrodes enables researchers to simultaneously record electrical signals and visualize neurons in the brains of awake mice1.
Syncing neuronal signals with videos of neurons helps researchers map those signals to particular sites in the brain. The technology could yield insights into how the brain works and what goes awry in conditions such as autism.
Two-photon calcium imaging and electroencephalography (EEG) are both popular tools for studying the brain, but combining them has proved challenging. In the former technique, researchers tag calcium ions with fluorescent proteins. When neurons fire, a microscope picks up the fluorescence as calcium ions rush into the cells. EEG requires inserting a recording electrode into the brain. However, the electrode blocks light in the area from reaching the microscope.
In the new study, researchers built electrodes that transmit light. They layered a metallic material into a flat plastic mold, roughly the size of a single neuron, that is studded with hundreds of plastic spheres. The material fills the space around the spheres, creating holes that allow light to pass through.