Response characteristics of neurons in each column of the primary auditory cortex (Al) of Mongolian gerbils were studied by single-unit recording. Tone-burst stimuli were presented to the ear contralateral to the recording side. During a near-radial microelectrode penetration of Al in steps of 100 (mu)m, best frequencies (BFs), best thresholds, best amplitudes (BAs), latencies, tuning curves, and Q[inf 10 dB]'s, defined as BF/(frequency bandwidth 10 dB above the best threshold), were measured. Neurons in single penetrations had similar BFs, showing columnar organization of frequency, but had various values of best thresholds (19.1--81.3 dB SPL), BAs (44.9--102.1 dB SPL), latencies (5--80 ms), and Q[inf 10 dB]'s (0.34--17.53). There was a tendency for high Q[inf 10 dB]'s to be located around layer IV, while there was no tendency in the distribution of low Q[inf 10 dB]'s, best thresholds, and BAs. These results provide a layer specificity of tuning properties within a single column of frequency.