Fig. 2.

Intrinsic activity in the absence of sensory stimuli monitored in transgenic mice expressing VSFP Butterfly 1.2 in layer II/III pyramidal neurons. (a) Dorsal view over both cortical hemispheres of a mouse with a chronically implanted transcranial window, captured through the FRET donor (upper) and acceptor (lower) channels. Four ROIs are outlined as: (i) left motor cortex (navy), (ii) right motor cortex (cyan), (iii) left visual cortex (red), and (iv) right visual cortex (pink). (b) Intrinsic activity imaged across both hemispheres in the absence of sensory stimulation under light sedation. Upper: individual donor (green) and acceptor (red) fluorescence signals averaged across both hemispheres; middle: ratiometric voltage signal across both hemispheres; lower: ratiometric voltage signal of intrinsic activity across the four ROIs [left motor cortex (navy), right motor cortex (cyan), left visual cortex (red), and right visual cortex (pink)] as outlined in A lower, showing isotopic cortical activity traversing across large distance in both hemispheres. These data were collected as described in Akemann et al.¹¹ and Carandini et al.¹⁴