Generation of a Synthetic Memory Trace

Abstract

Adding Artificial Associations In the mammalian cortex, there is significant spontaneous neural activity that is internally generated, rather than arising from sensory inputs, and this activity influences the processing of natural sensory stimuli. What role does this internally generated activity play in forming and accessing new memory representations? Using transgenic mice combined with controlled artificial activation of widely distributed neuronal ensembles associated with specific contexts, Garner et al. (p. 1513 ; see the Perspective by Morris and Takeuchi ) investigated how spontaneous neuronal activity is integrated into a given context representation. Animals underwent fear conditioning in two distinct contexts. When a circuit in one context was artificially activated during fear conditioning in a separate context, a so-called “hybrid” memory was formed. This artificially stimulated network became a necessary component of the memory trace. These results are consistent with the emerging view that internally generated brain activity is not noise, but a coherent representation that can be incorporated into new associations and memories.