Functioning neurons have precisely controlled membrane potentials and electrical currents flowing through ion channels. These electrical properties are integral to their role in communicating signals throughout the nervous system. Are you interested in studying pathphysiology, pharmacology, or the molecular and cellular processes that govern signaling? Electrophysiology techniques are used to experimentally probe the electrical properties of neurons. A variety of techniques are employed to directly or indirectly measure changes in electrical currents that flow across cell membranes or changes in the electrical potentials near the cell membranes.
Whole-cell recordings and patch recordings are obtained using specialized recording electrodes and amplifiers that make it possible to measure voltage changes while clamping the current, or measure currents while holding the voltage constant. These techniques allow for the study of ion channels, voltage sensitive proteins, and functional responses to neuro-active compounds. An example is shown of a whole cell recoding in current-clamp mode on BrainXell’s Spinal Motor Neurons (BX-0100) that exhibit spontaneous action potentials.
Whole-cell recordings and patch recordings are tedious techniques that require significant time for data acquisition. However, automated platforms are commercially available that offer improved throughput. As demonstrated here using a Qube 384 (Sophion), the electrophysiological properties of hiPSC-derived motor neurons produced by BrainXell can be characterized and Current-Voltage (IV) relationships for both sodium currents and potassium currents can be measured for dozens of cells.
The Qube 384 was also used to compare the phenotypes of SMA disease motor neurons to wild-type motor neurons. The NaV IV relationship of the SMA motor neurons displayed greater peak NaV current as compared to the control.
Extracellular recordings, which examine changes in electrical field potentials created by neurons that are adjacent to recording electrodes, can also be used to observe neuronal activity. This technique often utilizes Multi-Electrode Arrays (MEA) that record extracellular action potentials (spikes) from numerous neurons at the same time, allowing networks and synchronized signaling to be studied. Such recordings are non-invasive, examine the entire cell culture, and allow for repeated measurements to be made over time in the same plate.
MEA has also been used for functional phenotypic in vitro screening of patient iPSC-derived neurons.
