Creating a False Memory in the Hippocampus

TLDR

Memories can be unreliable. The study aimed to create a false memory in mice by optogenetically manipulating hippocampal engram cells. DG or CA1 neurons activated by a context were labeled with channelrhodopsin‑2 and later optically reactivated during fear conditioning in a different context. The optically reactivated engram produced a context‑specific false fear memory, evidenced by increased freezing in the original context, activation of natural fear circuits, and a behaviorally expressed fear response, demonstrating that artificial manipulation can generate an internally represented fear memory.

Abstract

Memories can be unreliable. We created a false memory in mice by optogenetically manipulating memory engram-bearing cells in the hippocampus. Dentate gyrus (DG) or CA1 neurons activated by exposure to a particular context were labeled with channelrhodopsin-2. These neurons were later optically reactivated during fear conditioning in a different context. The DG experimental group showed increased freezing in the original context, in which a foot shock was never delivered. The recall of this false memory was context-specific, activated similar downstream regions engaged during natural fear memory recall, and was also capable of driving an active fear response. Our data demonstrate that it is possible to generate an internally represented and behaviorally expressed fear memory via artificial means.