Although Karl Lashley did not succeed in finding a single physical engram, he proposed that memories are distributed throughout the entire brain rather than being stored in one specific area.

Google

Karl Lashley was a psychologist who, about a century ago, investigated the physical basis of memory. His research methodology involved creating lesions, or intentional damage, in the cerebral cortex of animals like rats and monkeys. This was part of his pioneering search for the engram, the physical trace of a memory, which ultimately led to his formulation of the equipotentiality hypothesis.

Karl Lashley

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

In an early attempt to physically locate the engram, Karl Lashley conducted experiments in which he created brain lesions in rats after they had learned to navigate a maze. He found that the rats retained the ability to find their way through the maze regardless of the size or specific location of the brain damage, demonstrating a lack of evidence for a localized memory trace.

Karl Lashley's Lesion Experiments

The equipotentiality hypothesis, formulated by Karl Lashley in 1950, posits that if a specific part of the brain involved in memory is damaged, another part of that same area can take over that memory function. Lashley developed this theory based on the animals' reactions in his lesion experiments, where rats could still navigate a maze regardless of the size or location of the lesion.

Learn Before

Related