Neurons use electrical pulses and chemicals to communicate with each other. Analyzing both is critical for studying brain function and spotting brain diseases, but today’s implants can measure only one or the other. Researchers have now made a multifunctional brain chip that can measure both electrical charges and neurochemicals in the brain and inject drugs in real-time. They tested the chip, which is smaller than a U.S. quarter-dollar coin, in live mice.
Measuring the concentration of neurotransmitters, the chemicals that transmit signals between neurons, can give pivotal insights into brain function. But measuring these neurotransmitter levels today (without innovations such as the brain chip) requires inserting a probe with a fluidic channel into the brain to collect brain fluid, which is analyzed using techniques like spectroscopy. That’s slow, and the millimeter-wide probes can cause tissue damage. Recording the brain’s electrical signals is more straightforward using ultrathin flexible polymer-based neural probes implanted in target brain regions or metal electrodes attached to the scalp.
Brain chip devices that can simultaneously measure electrical and neurochemical signals are hard to come by. One group recently reported tiny MEMS-based sampling devices that collect extracellular fluid without damaging tissue, but these devices cannot record electrical signals. Deciphering the quantitative relationships between those two signals in vivo would be valuable for neuroscience studies.