Microprobe Captures Dual Neuron Signals

Scientists at Quebec’s Laval University have devised a microprobe that allows them to make parallel optical and electrical measurements of individual neurons in live lab rats (Nat. Methods, DOI: 10.1038/nmeth.1572). Such a tool will help researchers determine whether detected electrical activity emanates from specific neurons that have been fluorescently labeled. Yves De Koninck and coworkers construct micrometer-scale probes featuring an optical core through which they can excite neurons and collect fluorescence and an electrolyte-filled hollow core with which they measure electrical activity. Using the probes, they achieved subcellular optical resolution of fluorescently labeled neurons in rat brain slices and in vivo in spinal cords. The researchers used the distance between the positions of the optical and electrical peaks to determine whether the signals came from the same neuron. They also measured spontaneous Ca²⁺ release from single neurons via both fluorescence and electrical signals. The team further used the probes to trigger and measure the activity of light-gated channels in individual neurons. De Koninck and coworkers expect the method will be useful for distinguishing the activity of sparsely distributed neuron subtypes against a background of other neurons.