Transcranial flavoprotein-autofluorescence imaging of sound-evoked responses in the mouse auditory cortex under three types of anesthesia

Abstract

The effects of anesthesia on the functional auditory characteristics of cortical neurons, such as spatial and temporal response properties, vary between an anesthetized and an awake subject. However, studies have shown that an appropriate anesthetic method that approaches the awake condition is still useful because of its greater stability and controllability. The present study compared neural response properties from two core fields of the mouse auditory cortex under three anesthetic conditions: urethane; ketamine and xylazine hydrochloride (KX) mixture; and a combination of medetomidine, midazolam, and butorphanol (MMB). To measure sound stimulation in vivo, we recorded flavoprotein-autofluorescent images of endogenous green fluorescence. Under all conditions, fluorescence changes in auditory core subfields in response to tones were observed, and response properties, such as peak intensity, latency, duration, and activated areas were analyzed. Results showed larger response peak intensity, latency, and duration in the core subfields under urethane compared with KX and MMB, with no significant differences between KX and MMB. Conversely, under KX anesthesia the activated areas showed characteristic response properties in a subfield-dependent manner. These results demonstrated the varied effects of anesthesia on response properties in the core subfields of the auditory cortex.