Correlation analysis
To assess the possible relationship between abnormal ALFF values and corneal chemical sensitivity, we conducted Pearson’s correlation analyses of the ALFF values and eye blinking in the 30s after capsaicine or menthol application (significance level: P< 0.05).
Insular cortex administration
Cyclotraxin-B (HY-P1178, MCE, New Jersey, USA) was dissolved in physiological saline and injected into insular cortex using a dual channel microinjection pump (SP200, Shenzhen Huayang Biotechnology Co., Ltd). Infusion cannulas (RWD Life Science Co., Ltd) were placed in the target insular cortex (50 nl, bregma 0.14 mm; lateral ±3.65mm; ventral -4.0mm) and cemented to the skull using dental cement (Lang Dental Manufacturing). After surgery, dummy cannulas were inserted, and caps were screwed to keep the guide cannula from becoming occluded. Mice were allowed 7 days to recover.