Heroes of the Engram

Abstract

In 1904, Richard Semon introduced the term "engram" to describe the neural substrate responsible for (or at least important in) storing and recalling memories (i.e., a memory trace). The recent introduction of a vast array of powerful new tools to probe and manipulate memory function at the cell and neuronal circuit level has spurred an explosion of interest in studying the engram. However, the present "engram renaissance" was not borne in isolation but rather builds on a long tradition of memory research. We believe it is important to acknowledge the debts our current generation of scientists owes to those scientists who have offered key ideas, persevered through failed experiments and made important discoveries before us. Examining the past can also offer a fresh perspective on the present state and future promise of the field. Given the large amount of empirical advances made in recent years, it seems particularly timely to look back and review the scientists who introduced the seminal terminology, concepts, methodological approaches, and initial data pertaining to engrams. Rather than simply list their many accomplishments, here we color in some details of the lives and milestone contributions of our seven personal heroes of the engram (Richard Semon, Karl Lashley, Donald Hebb, Wilder Penfield, Brenda Milner, James McConnell, and Richard Thompson). In reviewing their historic role, we also illustrate how their work remains relevant to today's studies.

Figure 1.

Images of our heroes of the engram. Left to right: Top, Richard Semon, Karl Lashley, Donald Hebb, Wilder Penfield. Bottom: Brenda Milner, James McConnell, Richard Thompson. Richard Semon: Picture in public domain due to its age. Karl Lashley: Reproduced with permission from the University of Chicago Photographic Archive (apf digital item number, e.g., apf1–03675), Special Collections Research Center, University of Chicago Library. Donald Hebb: Reproduced with permission from the McGill University Archive. Wilder Penfield: Reproduced with permission from the McGill University Archive. Brenda Milner: Reproduced courtesy of McGill University. James McConnell: Reproduced with permission from the Bentley Historical Library, University of Michigan. Richard Thompson: Reproduced with permission from the Society for Neuroscience.

Figure 2.

Images of copy of Worm Runner's Digest. Courtesy of Larry Stern, Professor of Sociology, Collin College (Plano, Texas).