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Zariwala, H.A. et al. J. Neurosci. 32, 3131–3141 (2012).

Calcium imaging has proven invaluable for monitoring the activities of neuronal populations, dendrites and dendritic spines both in vitro and in vivo. These experiments are increasingly done using genetically encoded calcium indicators such as the GFP-based GCaMP family. Recently, transgenic mouse lines expressing improved versions of these indicators have been generated. Zariwala et al. generated a Cre-dependent reporter mouse that expresses GCaMP3. A cross of these mice with appropriate Cre mouse lines produced robust GCaMP3 expression in defined cell populations in the retina, cortex and cerebellum. Chen et al. report transgenic lines expressing either GCaMP2.2c or GCaMP3 under the control of the Thy1 promoter. These mice showed GCaMP fluorescence in subsets of neurons in different brain regions and produced long-term, stable expression of the GCaMPs, with no apparent toxicity. The lines will be useful tools for long-term in vivo monitoring of neuronal activity.