Spike-history gating of plateau potentials enables closed-loop rewriting of CA1 representations

New research suggests that the timing of a specific type of electrical activity in hippocampal CA1 neurons plays a crucial role in determining when and where these brain cells can form or shift memory-related patterns, known as place fields. According to the findings, the recent history of a neuron's firing activity acts as a gatekeeper, permitting plasticity-inducing events only when the cell has a brief respite from continuous firing. This gate mechanism serves to suppress repeated plasticity during sustained neuronal firing.

Using a two-part computer simulation model of CA1 neurons, researchers found that this gate interacts with signals from the entorhinal cortex, a brain region involved in memory processing. The model demonstrated that existing memory representations can influence the precise location of future plateau potentials, leading to gradual changes in place fields over time.

This dynamic system also allows for the reinforcement of memory traces associated with rewards, as well as the recovery and reinstatement of specific memory patterns on different days.

The researchers further suggest that the amount of residual activity following a plasticity event could bias subsequent plateaus towards previously established memory locations. By reexamining existing experimental data, the team identified this relationship and confirmed it within their model. Ultimately, the study's findings reveal that the expression of neural representations may not only facilitate memory encoding but also dictate when and where these representations are subsequently rewritten.