In 1889, nearly 20 years before Horsley and Clarke published their paper on the use of stereotaxy to examine the brain, Dmitrii Zernov, a professor of anatomy at Moscow University, invented the first prototype of a stereotaxic instrument, an arc-based device for cerebral mapping that he called an encephalometer. Zernov briefly described this device in  preliminary communication published in the Russian journal Trudy Fiziko-meditsynskogo Obshestva Moscovskogo Universiteta (Vol. 2 [1889]: 70-80).

Two years later Zernov’s student Nikolai Altukhov provided a complete description of the encephalomete, including six detailed projection maps based on 40 post-mortem examinations. “Projections of anterior and posterior parts of the corpus callosum, insula and some basal ganglia (thalamus, nucleus lenticularis and caput nuclei caudate) were localized on the surface of the head. [Altukhov] also noted similarity in female and pediatric brains and concluded that the former are underdeveloped” (Lichterman, p. 3). Since both Zernov and Altukhov’s papers were published only in Russian, Western scientists did not learn of Zernov’s encephalometer until much later. Lichterman, “The first instrument for cerebral mapping: Zernov’s encephalometer and its modifications,” Kopf Carrier no. 61 (April 2005): 1-5.