Auditory cortical neurons in the cat sensitive to the direction of sound source movement

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The neural mechanisms involved in the detection of moving sounds were studied by recording single-neuron responses from primary auditory cortical cells in cats, which were paralyzed and under neuroleptanalgesia. A subpopulation of 25 cells was selected on the basis of brief preliminary tests, from among a group of 60 cells, for quantitative analyzes with a moveable sound source. We recorded, in repeated trials, responses to stationary tones presented from different angles around the animal's head and to the movement of the sound source in several directions in different planes and sectors. Per-stimulus-time (PST) histograms from the responses of each trial series were compiled with a computer. In 5 cells the response patterns depended on the place of the sound source but not on the movement of the sound. Eight cells responded selectively with sustained excitation to the movement of the sound source in a specific direction in a certain sector butreacted either with inhibition or with phasic ‘on’ and ‘off’ responses, or both, to stationary tones presented from different directions. These findings indicate that some cells in the primary auditory cortex of the cat perform a special function in the detection of the direction of sound source movement.