Investigating a Role of the Lateral Entorhinal Cortex in Temporal Duration Memory: Contextual Discrimination of Temporal Sequences

The lateral entorhinal cortex (LEC) is proposed to be a site of origin of a timing signal that is transmitted to the hippocampus for the generation of episodic time. However, the LEC’s role in temporal duration memory remains elusive. The present study investigated effects of LEC inactivation on retrieval and acquisition of temporal duration memory. Rats were trained on a novel temporal duration task to discriminate event sequences comprising cues of differing durations. Rats learned to press a lever for food reward upon hearing one auditory sequence and another lever for reward for a second sequence. Pharmacogenetic inactivation of the LEC post-acquisition left memory expression intact on tests of recognition memory. In a subsequent experiment, inactivation of the LEC prior to daily training revealed behavioural differences in early acquisition that diminished with time. These data implicate the LEC in early encoding, but likely not retrieval, of temporal duration memories.M.A