[Role of higher divisions of the auditory system in localizing a moving sound source]

Impairment of the ability to localize a moving acoustic image was studied in animal (dogs) following experimental ablation of the auditory cortical areas, and in patients following unilateral electro-shock seizures and focal injuries of the temporal cortex. Unilateral ablation of AI, AII and Ep areas in animals produces a disturbance in differentiation of parameters of a moving acoustic image, while a bilateral ablation results in disappearance of the ability to localize the image. After left-side electro-shock seizures in the patients, localization of movement of the acoustic image did not differ from the normal, while after right-side seizures, the trajectory of the image movement was sharply shortened and shifted to the right. In the case of a focal injury of the patient's left hemisphere, localization changes were of a diffuse nature (shortened trajectory of movement both on the right and left side). In the case of a right-side focus, the trajectory of the movement of the acoustic image on the side of the lesion did not differ from the normal, while on the opposite side it was sharply shortened and shifted towards the mid-line of the head. The conclusion has been made that there is a specialization in the human right hemisphere in achieving spatial hearing, while it is absent in animals.