Stimulus level of dichotically presented tones and cat superior olive S-segment cell dcharge.

Knowledge of the frequency of the stimulus and existing interaural intensity differences are inadequate for predicting S‐segment cell discharge rates. The stimulus level, re threshold, of dichotically delivered tones must also be known. At low stimulus levels, the most active population of S‐segment cells consists of cells whose CF's are tuned to the frequency of the stimulus tone. As stimulus levels of dichotically delivered tones increase above threshold. cells with CF's not tuned to the stimulus frequency tend to discharge at rates higher than those of the cells initially responsive at low levels. The higher the stimulus level the greater the discrepancy in frequency between the CF's of the most active cell population and the stimulus. Thus, the locus of maximum activity within the S segment is dependent not only on the frequency of the dichotically delivered stimulus tone but also on its stimulus level. [Research supported in part by U. S. Public Health Service.]