General Anesthetics’Effects On The Brain Functional Connectivity

Objective:The brain information integration processing not only relies on the central nervous system on the connectivity of the anatomical structure, but also on its function connectivity. With the resting state functional magnetic resonance (rs-fMRI) technology, we study the effects of general anesthetics (propofol and sevoflurane) on the brain functional connectivity and discuss the possible target site in the brain of propofol and sevoflurane and mechanism of loss of consciousness induced by the general anesthetics.Methods:Thirty ASA classification I patients undergoing selective butterfly pituitary tumor resection were enrolled. All the subjects are randomly divided into propofol (group P) and sevoflurane group (group S) and receive general anesthesia. Induction was performed by two different manners and mechanical ventilation was applied after tracheal intubation. The induction protocol of group P:propofol TCI4.0μg/ml, Remifentanyl1.0μg/kg and scholine1mg/kg. The propofol is maintained at a stable concentration TCI4.0μg/ml in the entire process. The induction protocol of group S:sevoflurane concentration at8%, fresh gas flow at6L/min, Remifentanyl Remifentany1 1.0μg/kg and scholine1mg/kg. Inhaled density of sevoflurane is maintained at2.6%(1.3MAC),fresh gas flow at2L/min.Three times of rs-fMRI scanning are performed respectively in awake, anesthesia and pain stimulating state. AFNI software is used to analyze the change of brain functional connectivity. Paired t test which programmed by AFNI and SPSS16.0is used for statistical analysis. P＜0.01is considered significant.Results:Compared with the awake state, the brain functional connectivity of default network, somatic sensory motor cortex and the network consisted of pain-related brain regions are diminished in varying degree at the level of surgical anesthesia caused by propofol and sevoflurane. The results of P group show that Cingulate, Medial prefrontal and insular cortex are suppressed.(P<0.01).In the S group, less brain region were suppressed, such as cingulate, superior frontal gyrus, superior temporal gyrus, lingual gyrus and cerebellum brain regions. In the state of pain stimulation, the brain functional connectivity in somatic sensory motor cortex and the network consisted of pain-related brain regions are recovered, the result of P group indicated that the right lingual gyrus, fusiform gyrus, insular cortex and cingulate are activated. The precuneus, fusiform gyrus and cerebellar vermis are activated in S group (P0＜0.01). The functional connectivity of default network is declined in further.(P＜0.01)Conclusion:At the level of surgical anesthesia, propofol and sevoflurane can reduce brain metabolic activity, which appears as a form of reduction of functional connectivity in brain networks and between the two hemispheres. All of the changes are related closely to reduction of the level of consciousness. Cingulate, Medial prefrontal and insular cortex may be the target sites of propofol in central nervous system. The sensitive target sites of sevoflurane in central nervous system may be the precuneus, fusiform gyrus and cerebellar vermis.