Scientists at the Allen Institute and HHMI's Janelia Research Campus have developed a new protein sensor capable of recording the incoming chemical signals in brain cells. This engineered protein, called iGluSnFR4 (pronounced 'glue sniffer'), is designed to detect the neurotransmitter glutamate as it is released into synapses. Glutamate plays a central role in neural communication, learning, memory, and emotion.
Previously, researchers could only record outgoing electrical signals from neurons. The ability to measure incoming signals—especially those as faint and fast as glutamate transmission—was limited by existing technology. The new indicator allows scientists to observe these subtle chemical exchanges in real time within living brain tissue.
According to Podgorski, "Neuroscientists have pretty good ways of measuring structural connections between neurons, and in separate experiments, we can measure what some of the neurons in the brain are saying, but we haven't been good at combining these two kinds of information. It's hard to measure what neurons are saying to which other neurons." He added: "What we have invented here is a way of measuring information that comes into neurons from different sources, and that's been a critical part missing from neuroscience research."
Jeremy Hasseman, Ph.D., a scientist with HHMI's Janelia Research Campus said: "The success of iGluSnFR4 stems from our close collaboration started at HHMI's Janelia Research Campus between the GENIE Project team and Kaspar's lab. That research has extended to the phenomenal in vivo characterization work done by the Allen Institute's Neural Dynamics group. This was a great example of collaboration across labs and institutes to enable new discoveries in neuroscience."
The development addresses a longstanding challenge for neuroscientists: monitoring how brain cells receive information through thousands of synaptic inputs. Older methods lacked either speed or sensitivity for detecting single-synapse activity.
With iGluSnFR4 now available through Addgene, researchers may gain deeper insights into how neural circuits function and interact.
