Fig. 1
Design of optogenetic CSD induction and headache-related behavioural assessments. A CSDs were induced in the primary motor cortex (M1) in a minimally invasive manner by optogenetic stimulation through the intact skull. Two silver ball-tip electrodes were connected to the skull overlaying the visual and parietal cortex for direct current (DC) recording of the CSD-related DC shifts. B After 20-min baseline recording, three CSDs were induced optogenetically within a time window of 10-15 min. Behavioral monitoring was performed before CSD at baseline, and after CSD, i.e. at 30 min, 24 h, 48 h, and 72 h after the 3rd CSD. Brains were harvested from naïve mice and mice that underwent CSD (at the four time points mentioned). C-F Mouse grimace scale (MGS) scores were monitored and recorded with examples shown, that is C 20 min before CSD induction; D at the time of CSD induction (example shown of a video-still with a MGS score of 0.4); E at 30 min after the 3rd CSD (example shown with a MGS score of 1.2); and F at 72 h after the 3rd CSD (example shown with a MGS score of 1.6). G, H Example video-stills of oculotemporal (OT) (head grooming) strokes in a mouse at 30 min after the 3rd CSD