In 1981, the Norwegian physiologist and cyberneticist, Rune Aaslid, developed a device which made it possible to apply the transcranial Doppler sonographic technique in man. In 1983, Dr. Albrecht Harders took on the project of working out a clinically practicable method that would allow atraumatic measurements to be made of the blood flow velocity in the large branches ofthe circle of Willis. The technique has now become a competitor of the conventional methods of measuring the intracranial hemodynamics, including angiography and the xenon method of cerebral blood flow measurement. Harders...