[The neuronal reactions of the frog midbrain to tones modulated in amplitude by pseudorandom noise]

Impulse responses of single units located in the torus semicircularis of the immobilized lake frog (Rana ridibunda) to long-lasting characteristic frequency tones modulated by low-frequency pseudorandom noise were registered. Period histograms locked to the direct and inverted modulating waveform with duration of 512 ms were obtained for 32 units. The majority of the histograms revealed the rectification of the envelope waveform in the neural discharge patterns. So, the difference histograms were calculated which in some units represented the stimulus envelope waveform rather well. Other units strongly emphasized the envelope maxima in their responses. In many cases only a few maxima of the envelope were represented in the period histograms. There were neurons that retained peculiarities of their response in the wide range of the carrier intensities.