Figure 2.
Wide-field imaging reveals global changes in cortical processing
(A and B) Wide-field calcium imaging in Emx1-RCaMP mice. (A) Fluorescence images of an ex vivo fixed brain in dorsal view (left) and a coronal section of somatosensory area (right) showing RCaMP expression in pyramidal neurons in deep and superficial layers. (B) In vivo fluorescence image of the tilted (24 degrees) left dorsal hemisphere through a transparent, intact skull preparation (left). In vivo images were registered to the Allen Mouse Brain Atlas (right). Cortical areas targeted for electrophysiological experiments are indicated: wS1, primary whisker somatosensory cortex; wS2, secondary whisker somatosensory cortex; wM1, primary whisker motor cortex; wM2, secondary whisker motor cortex; Aud, auditory area; Vis, visual area; PPC, posterior parietal cortex; tjM1, primary tongue and jaw motor cortex; ALM, anterior lateral motor area.
(C) Grand-average time course of global cortical activity in hit trials for novice versus expert mice. Each frame shows ΔF/F0 without temporal smoothing (10 ms/frame). For each pixel, baseline activity in a 50-ms window before visual cue onset was subtracted. Mean calcium activity of 62 novice and 82 expert sessions from seven mice, novice and expert difference, and the statistical significance of the difference (p value of Wilcoxon rank-sum test, FDR corrected, p < 0.05) are plotted from top to bottom. Green traces, anatomical borders based on Allen Mouse Brain Atlas. Black plus sign indicates bregma.
(D) Selectivity index in novice and expert mice. For each brain region, selectivity between hit versus correct-rejection trials was determined in non-overlapping 50-ms bins based on the area under the ROC curve. Mean selectivity of each area in 62 novice and 82 expert sessions from seven mice, and the statistical significance of the difference (p value of non-parametric permutation test, FDR corrected, p < 0.05) is plotted. Region-of-interest (ROI) size, 3 × 3 pixels.