Fig. 4 Virus and FVIOs injection into the mouse CeA for the magnetothermal neuromodulation of fear behaviors. (a) Scheme of anti-His-FVIO-based magnetothermal neurostimulation of the CeA and fear behavior analysis of freely moving mice. (b) Confocal images of brain slices showing that the anti-His-FVIOs-FL (green) are located in the TRPV1-expressing CeA regions (red) of the mice. (c, d) Percentage of freezing time in mice after injection with different doses of anti-His-FVIOs (or anti-His-SPIOs) before and during AMF stimulation (H = 20 mT, f = 275 kHz). The black and red (or green) lines represent AMF OFF and AMF ON, respectively. One-way ANOVA was performed followed by a two-sided Student’s test with thresholds. (e) Latency to the start of the first freezing episode during AMF stimulation in mice. (f) DAPI (blue), c-fos (green) and overlay confocal images of the CeA regions of mice obtained after magnetothermal stimulation. (g) Percentage of c-fos-expressing cells in the CeA among the DAPI-labeled cells. Error bars indicate the mean ± SEM, two-sided Student’s t-test with the threshold ****P < 0.0001.