Fig 2. Thy1/GCaMP6 mouse model validation.

Based on previous studies, Thy1/GCaMP6 fluorescence should provide a signal predominantly driven by cortical neuronal neurons and that is faster than hemodynamic measures. (A) Epifluorescence (i) and confocal (ii) images of 50um coronal slices collected from a representative Thy1/GCaMP6 mice. GCaMP6 expression (green) is located throughout the cortex (i) and localized to neuronal soma (ii, blue-DAPI stain) and can be seen throughout cortical layers I-VI. (B) Map of stimulus evoked responses to electrical stimulation of left hindpaw (thresholded at >50% peak response) in the anesthetized state. (C) Time series of evoked responses sampled using masks created from the right half of the 50% peak response images in part B. Green reflectance (green trace, top panel) is used to correct raw GCaMP6 emission (teal trace) for changes in absorption due to hemodynamics using a ratiometric approach (see Methods; the corrected trace is black). The corrected GCaMP6 trace (black) is sensitive to each stimulus presentation (black trace, lower panel), whereas HbO₂ (red) and HbR (blue) follow the slower, canonical hemodynamic response. Error bars are standard error of the mean. Data from 36 blocks across 7 mice are included in all evoked analysis.