The formation of short-term memory (STM) is widely thought to be a prerequisite for long-term memory (LTM) consolidation. However, Shin et al. now report that inhibiting CaMKII — a kinase involved in the long-term potentiation (LTP) of excitatory synapses and implicated in multiple types of memory — blocks STM but not LTM of inhibitory avoidance in mice.

In the task central to the study, the authors trained mice over two sessions to avoid a dark compartment by delivering footshocks to the animals when they entered the compartment from an adjoining light compartment. They then placed the animals in the light compartment and assessed their latency to cross into the dark compartment shortly after training (to assess STM) and 1 day later (to assess LTM). Trained mice avoided the dark compartment, reflected by longer cross latencies, at both time points, which indicates the formation of STM and LTM.