In this paper, we address the enigma of the memory engram, the physical trace of memory in terms of its composition, processes, and location. A neurochemical approach assumes that neural processes hinge on the same terms used to describe the biochemical functioning of other biological tissues and organs. We define a biochemical process, a tripartite mechanism involving the interactions of neurons with their neural extracellular matrix, trace metals, and neurotransmitters as the basis of a biochemical memory engram. The latter inextricably link physiological responses, including sensations with affective states, such as emotions.