Abstract: Objective To compare tonal response properties of neurons in the primary auditory cortex of Sprague-Dawley rats
anesthetized with urethane and ketamine-xylazine. Methods Forty-five female Sprague-Dawley rats (200-250 g) were
randomized into two groups and anesthetized with urethane or ketamine-xylazine. Tone pips were chosen as the stimuli to
obtain the action potentials of the single neurons by in vivo cell-attached recording. The features of the action potentials were
extracted with Matlab software to comparatively analyze the acoustic response properties of the neurons between the two
anesthetic groups. Results The Q values and the characteristic frequencies were independent of the types of anesthetic agents,
but with urethane anesthesia, the neurons tended to have higher minimum thresholds, lower spontaneous firing rates, longer
response latencies, and more frequent occurrence of tuning with stronger inhibition compared to those in ketamine-xylazine
group. Conclusion Urethane and ketamine might have no obvious impact on the transmission pathway of frequency tuning
from the periphery to the auditory cortex, but neurons from rats with urethane anesthesia receive enhanced inhibition
mediated by the interneurons or have a lower intrinsic excitability.