4OY4:
reference: Neural circuits. Labeling of active neural circuits in vivo with designed calcium integrators., Fosque BF, Sun Y, Dana H, Yang CT, Ohyama T, Tadross MR, Patel R, Zlatic M, Kim DS, Ahrens MB, Jayaraman V, Looger LL, Schreiter ER, Science. 2015 Feb 13;347(6223):755-60. doi: 10.1126/science.1260922. PMID: 25678659

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