(a). Epifluorescence image of GCaMP-6f fluorescence through MEC microprism (top) and two-photon imaging FOVs through MEC microprism (bottom). Red dot indicates location of Alexa494 pin marking shown in the histological section. (b). Post-mortem histological sagittal sections from same mouse as in a covering region of MEC labeled with GCaMP6f (green). Morphology shown with DAPi staining (blue) and location of pin marking shown with Alexa594 labeling (red). The presence of lamina dissecans, the relative position of the post-rhinal border to the pin mark and the circular shape of the dentate gyrus shown at the medial-lateral position of the sagittal sections indicates recordings were made in MEC. c. Same as b, but magnified view of GCaMP6f region. Cortical layers marked with red dashed lines. d. Same as c, but only DAPi shown. Repeated 5 times across 5 mice with similar results.