General Biology Seminar

The idea that memory is stored in the brain as physical alterations goes back at least as far as Plato, but further conceptualization of this idea had to wait until the 20th century when two guiding theories were presented: the "engram theory" of Richard Semon, published at the turn of the century but largely forgotten until the 1970s, and Donald Hebb's "synaptic plasticity theory," posited in 1949. While a large number of studies have been conducted since, each supporting some aspect of these theories, they all fell short of providing integrative evidence for the existence of engram cells and circuits as defined by the theories. During the past few years, the advent of transgenics, optogenetics, and other technologies has allowed neuroscientists to identify memory engram cells, engineer them to evoke memory recall, and demonstrate that these cells indeed undergo synaptic, cellular, and circuit changes, thus linking the two major concepts in memory research. Furthermore, the engram engineering technology is allowing neuroscientists not only to reinvestigate fundamental mnemonic phenomena like memory consolidation, but also to implant false memory or restore memory-related disorders in animal models.