[Characteristics of the reactions of neurons of successive links in the auditory pathway to changes in the timing of acoustic signals]

Abstract

Afferent impulsation was compared for different levels of the auditory system: the cochlear nuclei, posterior colliculi, and the auditory cortex. While moving from the cochlear nuclei over to the posterior colliculi and the auditory cortex, the number of neurons describing the temporal structure of the amplitude-modulated signal's envelope in the impulse activity pattern, becomes sharply reduced; the number of neurons selectively responding to certain phases of the envelope increases; the firing rate of neurons of the auditory pathway's higher levels decreases; the repetition rates becomes narrow due to limitation from both the high- and the low-frequency sides. Selectivity of responses to combination of such signal parameters as the frequency of the carrier and the rhythm of the amplitude modulation, increases. Specificity of the neuronal responses increases on certain combinations of such parameters of the frequency-modulated sounds as the frequency range in the signal, the direction and speed of the frequency modulation. The data obtained revealed some general tendencies of the impulsation transformation in successive levels of the auditory pathway.