Probing Deep Brain Circuitry: New Advances in in Vivo Calcium Measurement Strategies

The study of neuronal ensembles in awake and behaving animals is a critical question in contemporary neuroscience research. Through the examination of calcium fluctuations, which are correlated with neuronal activity, we are able to better understand complex neural circuits. Recently, the development of technologies including two-photon microscopy, miniature microscopes, and fiber photometry has allowed us to examine calcium activity in behaving subjects over time. Visualizing changes in intracellular calcium in vivo has been accomplished utilizing GCaMP, a genetically encoded calcium indicator. GCaMP allows researchers to tag cell-type specific neurons with engineered fluorescent proteins that alter their levels of fluorescence in response to changes in intracellular calcium concentration. Even with the evolution of GCaMP, in vivo calcium imaging had yet to overcome the limitation of light scattering, which occurs when imaging from neural tissue in deep brain regions. Currently, researchers have created ...