In this year, we conducted three major sub-projects. First, we employed glucose-sensitive sensors coupled with high-speed amperometry to evaluate rapid fluctuations in brain glucose levels following exposure to heroin and fentanyl. Second, we employed oxygen microsensors to examine fluctuations in brain oxygen levels induced by these two opioid drugs. The changes in these two metabolism-related substances were examined in relationships with changes in metabolic brain activity and peripheral vascular tone.