[Reactions of tonic-type neurons in the cat auditory cortex to tones of various frequency and intensity].

Extra- and intracellularly recorded responses of the acoustic cortex neurons to sound tones of different frequency and intensity and peculiarities of the organization of receptive fields of these units were studied in immobilized cats. Special attention was paid to neurons with tonic spike responses to these stimuli. Such tonic-type neurons were met in different cortical layers but most of them (93%) were localized at depth of 1.0-2.2 mm. Mean response threshold of these cells was lower by 7.7 dB than that of phasic-type neurons. Tonic-type units were characterized by lower frequency-discriminative ability in comparison with phasic ones: mean values of Q10 were 4.1 +/- 0.4 and 9.1 +/- 0.7, respectively. Dimensions of receptive fields of tonic-type units were 3.5 times as large as those of phasic ones. Most of tonic-type neurons (80%) differed from phasic ones in 1.5-2.0 time shorter action potentials. Tonic neurons demonstrated high sensitivity to variations of duration and intensity of the acoustic stimulation.