[Comparative physiological characteristics of the neuronal impulse activity of the midbrain auditory centers in amphibians and mammals].

Comparative studies have been made on the neuronal activity of the midbrain auditory centers of the frog, guinea pig, rat and cat during the effect of sonic signals of various frequency, duration and intensity. It was shown that with the higher taxonomic position of the animal, the range of activating frequencies also increases, together with the increase in the sharpness of frequency tuning of the neurones and the increase in absolute sensitivity of the latter in the band of frequencies of the best sound perception. Minimal latency values for midbrain neuronal reactions decrease, whereas their distribution range becomes more narrow. The depth of temporal summation increases, while the decrease is observed in the duration time of summation in those neurones which are sensitive to transient phenomena in sonic signals. Possible reasons are discussed which account for the differences in time-frequency properties of the auditory system among vertebrates.