The memory engram: beginning the search.

Some of the earliest conceptual milestones in memory research with relevance to the physical means through which its preservation is made possible, namely, the 'memory trace' or 'engram', are analysed in this study. The fundamental notions were laid down by Platon and Aristoteles. While Platon regarded memory as an imprint on a 'wax block' in the immortal soul, Aristoteles considered memory a modification in the mortal soul, imprinted like a cast at birth time. The Roman orators were interested in mnemotechnics, and Cicero is credited for the term 'trace' (vestigium) used for the first time. Much later, Descartes described the (memory) 'trace' (trace), linking psychic, and physical processes. Finally, Semon posited innovative concepts and terms centralized by the 'engram' (Engramm). The search of this important question, which begun about two and a half millennia ago, continues in focus, as can be seen through the growing rate of published papers on the subject.