[Role of the auditory cortex in the formation of complex reflexes to amplitude-modulated stimuli in rats].

Motor alimentary conditioned reflexes to acoustic stimuli were elaborated in 27 laboratory rats. After bilateral ablation of the auditory cortex, differentiation of tonal stimuli from amplitude-modulated (AM) signals with a 5 c/s modulation frequency was completely abolished, without its subsequent restoration in six months after the operation. Differentiation of tonal from AM-stimuli with a 50 and 500 c/s modulation frequency, however, not only persists, but is elaborated in animals with a preliminarily ablated auditory cortex. Results of the investigation permit to draw the conclusion that the auditory cortex is the centre where the coding of stimuli with a low frequency of amplitude modulation is completed. Correspondingly, the structural organization of the sensory part of the arc of conditioned responses to different classes of AM-stimuli is discussed.