Memories are thought to be stored as material changes occurring in sparse, widely distributed populations of neurons known as engrams. This neural plasticity is theorised to promote re-activation of this network of engram cells upon re-exposure to relevant cues, thus leading to memory retrieval. Significant evidence exists to support this theory in relation to highly aversive or rewarding experiences, however less evidence exists to support the existence of engrams for day-to-day learning experiences. Here we used TRAP2 mice to characterize expression patterns and plasticity in neurons activated by the object-in-place associative memory task, focussing on the lateral entorhinal cortex (LEC). We found that, compared to control animals, LEC was robustly activated by the object-in-place task. Moreover, there was a selective increase the ratio of active cells in deep versus superficial LEC layers compared to animals that had explored an empty but novel arena suggesting that object-place information is enriched within deep layers of LEC. Chemogenetic silencing of TRAP2 neurons LEC impaired retrieval of object-in-place memory, implicating these neurons as engram cells. Electrophysiological recordings revealed heightened intrinsic excitability and increased levels of firing in deep layer TRAP2-labelled neurons in LEC when animals had been exposed to a novel configuration of the objects used at time of engram labelling. No increase in excitability was observed in response to a familiar configuration of the engram object set, nor by exposure to an entirely new set of objects, indicating that neuronal excitability in deep layers of LEC may encode novel information into existing representations.