[Frequency characteristics of central auditory neurons following a decrease in the number of periods of excitatory pure tones].

In anesthetized rats, frequency-threshold curves of the inferior colliculus neurons to signals with various number of cycles in a pure tone burst (n=1;10;f/1000X50), were estimated. A great majority of neurons were characterized by pronounced frequency selectivity even to signals containing one cycle. Response thresholds mainly depended on the tone frequency; the maximal threshold sensitivity was obtained at the same frequency when tested with 1 or 10/sec sine wave and 50 msec duration tone. Sharpness of the frequency-threshold curve depends both on duration of signal and discharge pattern of the neuron: when the signal duration decreases sharpening of the frequency-threshold is observed in neurons with initial response, while flattening of the frequency-threshold curve is observed in neurons with sustained response.