fMRI study on effect of ketamine on cerebral function in dogs

    SUN Xuª²De, ZHANG Hui, XU Liª²Xian, CHAI Wei, GE Yaª²Li, ZHANG Jinª²Song, ZHANG Guiª²He, GAO Changª²Jun, HAN Liª²Chun

    Department of Anesthesiology, Tangdou Hospital, Xi¬ðan 710038, Department of Anesthesiology, Qindu Stomatological Hospital, Department of Radiology, Xijing Hospital, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To study the changes of NMR signal intensity in dog¬ðs cerebral regions after ketamine application, and to investigate specific brain regions that are sensitive to the anesthetic. METHODS: Stimulation procedure was performed from consciousness, to sedation, to unconsciousness, and finally to analepsia. Scan lasted 60 Dy. Ketamine was injected at a dose of 2 mg/kg with a constant speed infusion pump. Functional magnetic resonance imaging (fMRI) was applied during the entire experiment. A dynamic singleª²shot EPI sequence was used to perform BOLD functional MR imaging on a 1.5T Philips Gyroscan MR system and the Functool software was also used to analyze these images. RESULTS: For the ketamine anesthesia groups, the decreased signal intensity was observed at sensory cortex (r=0.79, 19.5%), at motor cortex (r=0.81, 16.6%), at thalamus (r=0.66, 4.5%), and at callosal gyrus (r=0.68, 4.7%). The changes of signal intensity were synchonous. However, there was no significant change in other subcortex regions. CONCLUSION: Ketamine anesthesia suppressed such regions as sensory cortex, motor cortex, thalamus and callosal gyrus, which might be the key targets for ketamine action. ......