Thus instead of being synonymous with specific procedures per- formed at the level of the basal ganglia, stereotaxis is in fact a general diagnostic and therapeutic concept, which has as its aim the precise three-dimensional representation of the patient's brain in its entirety. This three-dimensional representation is based on anatomical, neuro- radiological and other localizing information, the spatial integration Prof. Jean Talairach with friends and coworkers at the congress dinner in the Royaumont Abbey near Paris. (From left to right: Drs. ]. Bancaud, N. T. Zervas, B. Nashold, ]. Talairach, G. Szikla, F. Mundinger, P. Tournoux, ]. Peeker) of which allows a more precise "anatomical" approach to the human brain and to the surgical management of localized pathologic proces- ses. Literally, stereotaxis means "orientation in space". Taken in this general sense, all surgical procedures obviously should be stereo- tactic, at least in their principle! Two of the main themes of our meeting, namely the topic of the first day, "Surgery of Epilepsy" and that of the second "Stereotactic Cerebral Irradiation" of small brain tumours correspond to this evolution toward a global "whole brain" concept of stereotaxis. The same philosophy inspired the scientific efforts of the stereotactic group Introduction 3 of the Sainte Anne Hospital, under the leadership of its promoter, Professor Jean Talairach. This is the reason why the present Meeting is dedicated in honor of his scientific work.

has further broadened controversial though this subject and indeed the results of amygdaloidotomy may be. lt was Jinnai in 1963 who first published his work on the control of intractable epilepsy by interruption of conduction pathways of the epileptic discharge using stereotactic lesions in the field of Forel. This was followed by lesions in the thalamus by Mullen in 1967, and by capsular lesions by Bertrand in 1970 and myself in 1971. In the macroscopic form this was carried out by section of the inter hemispheric cerebral connections by open operation by Vogel in 1969. This has been an important contribution to knowledge of the basic mechanisms of the propagation of the epileptic discharge and to our understanding of brain function but I would look to stereotactic techniques for the greater development potential. There are, of course, limitations. Bilateral lesions of effective size are difficult to achieve without side effects, particularly in respect of speech (notably dysarthria) and yet are essential if intractable epilepsy is to be con trolled in severity and frequency. Increased accuracy of target siting and control of the size of lesion are not the whole answer for inevi tably there are areas where important neuronal circuits are very crowded. But we should not underestimate the contribution of surgery. Increasingly the medical therapy of epilepsy is under scrutiny."