Cranial window implants in head-fixed rodents are becoming a preparation of choice for stable optical access to large areas of the cortex over extended periods of time. Here we provide a highly detailed and reliable surgical protocol for a cranial window implantation procedure for chronic wide-field and cellular imaging in awake, head-fixed mice, which enables subsequent window removal and replacement in the weeks and months after the initial craniotomy. This protocol has facilitated awake, chronic imaging in adolescent and adult mice over several months from a large number of cortical brain regions; targeted virus and tracer injections from data obtained using prior awake functional mapping; and functionally targeted two-photon imaging across all cortical layers in awake mice using a microprism attachment to the cranial window. Collectively, these procedures extend the reach of chronic imaging of cortical function and dysfunction in behaving animals.
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acknowleDGMents The authors thank W.-C. Lee, M. Histed, D. Smith, K. Kuchibhotla and M. Henry for assistance in developing the initial window implant and headpost design; A. Vagodny, J. Curry, C. Holland, K. Levandowski and D. Woloszyn for technical assistance; and J. Maunsell for sharing his surgical rig during initial stages of development of these procedures. M. Kirk performed the window implant shown in Figure 9. We also thank members of the Reid and Andermann laboratories for useful discussions. We thank L.L. Looger, Janelia Farm Research Campus, Howard Hughes Medical Institute for provision of AAV-GCaMP3 (ref. 21) via the University of Pennsylvania Vector Core. We thank V. Jayaraman, R.A. Kerr, D.S. Kim, L.L. Looger and K. Svoboda from the Genetically-Encoded Neuronal Indicator and Effector (GENIE) Project, Janelia Farm Research Campus, Howard Hughes Medical Institute, for provision of AAV-GCaMP6 (ref. 22) via the University of Pennsylvania Vector Core. The writing of this protocol was supported by grants from the Smith Family Foundation, the Pew Scholars Program in the Biomedical Sciences, the Klarman Family Foundation, the Boston Nutrition and Obesity Research Center, the Association for Aging Research New Investigator Award in Alzheimer’s Disease and the Harvard– Massachusetts Institute of Technology (MIT) Joint Research Grants Program (M.L.A.).
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