General anesthesia changes gap-evoked auditory responses in guinea pigs

CONCLUSION. General anesthesia induced by sodium pentobarbital reduces temporal resolution as represented by an increase in the threshold of gap-evoked auditory responses in guinea pigs. OBJECTIVES. To explore the potential impact of general anesthesia by sodium pentobarbital (PB), a common anesthetic used in animal research, on gap-evoked responses. MATERIALS AND METHODS. The evoked potentials in response to gaps formed by bursts of broadband noise were recorded from electrodes implanted in the inferior colliculus (IC) and the auditory cortex (AC) of guinea pigs. The gap responses were compared in three conditions: unanesthetized and anesthetized with two doses of sodium pentobarbital (40 mg/kg and 20 mg/kg). RESULTS. PB increased the gap response thresholds, especially when applied at the higher dose. The threshold shift induced by PB was greater in the AC than in the IC. In addition, the higher dose of PB significantly increased the gap response latency in both IC and AC, and decreased response amplitude in IC only.