Next, we verified that anti-His-FVIO-mediated magnetothermal stimulation in vivo can efficiently and safely evoke quick behavioral responses in freely moving mice. The central amygdala (CeA) was chosen for in vivo magnetothermal deep brain stimulation because it plays a crucial role in physiological and behavioral responses to fearful stimuli[51]. And CeA has been widely used to evaluate the efficiency of various neuromodulation techniques, such as optogenetics[52]. Figure 4a schematically illustrates the process of using anti-His-FVIO-based magnetothermal neurostimulation of the CeA and fear behavior analysis of freely moving mice, whereas an adeno-associated virus was used to express a His-tagged TRPV1 and red fluorescent mCherry fusion protein in CeA mouse neurons. After viral transfection, the anti-His-FVIO suspension was injected into the CeA region. The immunohistochemical results showed that anti-His-FVIO-FL (green) colocalized with TRPV1-expressing neurons (red) in the CeA, suggesting that the anti-His-FVIOs successfully targeted TRPV1 channels (Figure 4b). After three days of recovery and habituation, the mice were transferred to a custom-made AMF generator coil equipped with a fear behavior video analysis system. An AMF apparatus with a 6-turn coil (diameter, 12 cm) was used here to produce an AMF with amplitudes up to 20 mT at a frequency of 275 kHz, to guarantee sufficient heat generation by the FVIOs to excite the CeA regions in the deep brains of the mice.