Anesthesia and EEG Discontinuity in Infants

Inclusion Criteria: * Infants who were born as full-term (\>37 weeks postconception) and are equal to or less than 12 month old who were scheduled to undergo surgery under general anesthesia using inhalation agents. * Belongs to American Society of Anesthesiologists Physical Status 1 or 2 Exclusion Criteria: * Infants who were born less than 37 weeks postconception or has history of mechanical ventilation immediately after birth * Presence of any genetic disease, chromosomal anomaly or congenital anomaly that can affect brain development * Presence of any disease or disability in central nervous system * History of trauma at head or surgery on brain * History of hypersensitivity to any anesthetic agents * Status of sedation or endotracheal intubation before induction of anesthesia * Inability to attach probes for EEG monitoring * Expectation of operation time as less than 5 minutes * Other conditions that researchers regard as inappropriate for enrollment