The role of the Dentate Gyrus and Perirhinal cortex in the formation of non spatial "pattern-separated" memories

FRANCISCO GALLO; MAGDALENA MIRANDA; BEKINSCHTEIN, PEDRO; PIROMALLI GIRADO, DINKA; FACUNDO MORICI, JUAN; NOELIA WEISSTAUB

Berlín

Congreso; 11th FENS Forum of Neuroscience, Berlin 2018; 2018

FENS

Successful memory involves not only remembering information over time but also keeping memories distinct. The ability to separate components of memories into distinct memory representations relies on pattern separation, a computational process by which similar events are disambiguated. Although pattern separation of spatial information has been localized to the dentate gyrus (DG), this function could also take place during processing of other types of information. The perirhinal cortex (PRH) is involved in the acquisition and storage of object memories, especially for tasks with ambiguous features. However, there is some debate on whether the DG participates in pattern separation of non spatial representations. Here we use a modified version of the object recognition task and manipulated the load of pattern separation during encoding of the task. We show that two plasticity-related proteins, BDNF and Arc, are required for pattern separation of object memories both in the PRH and the DG. Additionally, while exogenous BDNF was able to enhance pattern separation when injected into PRH, it was not effective when infused within the DG. Finally, BDNF injected into PRH was able to rescue the memory deficit produce by blockade of Arc in the DG and the AMPA antagonist DNQX, which blocks excitatory transmission, impairs overlapping object memory retrieval when injected in the PRH, but not in the DG. These results reveal a complex interaction between plasticity mechanisms in the PRH and the DG for non spatial pattern separation and posit the Prh as the key structure where unique object representations are stored.