Long-term memory formation of object in context task requires dorsal hippocampus and medial prefrontal cortex activity and it is interfered by another object in context experience.

VILLAR ME; MARTINEZ MC; BALLARINI F; VIOLA H

Milan

Congreso; 9th FENS Forum of Neuroscience, Milan, Italy, July 5-9, 2014.; 2014

FENS

Long-term memory formation of object in context task requires dorsal hippocampus and medial prefrontal cortex activity and it is interfered by another object in context experience. Villar ME, Martinez MC, Ballarini F, Viola H With the aim of analyzing if recognition long-term memory (LTM) formation is susceptible to retrograde interference (RI), we trained rats to learn two different trail associations between objects and their respective arena boxes. Separate group of subjects were tested in these contexts in order to evaluate the LTM for each associate pair (object-context). Furthermore, given the involvement of hippocampus (Hp) and medial prefrontal cortex (mPFC) in several recognition memories, we also analyzed the participation of these structures in the LTM formation of the object in context task by the local infusion of muscimol. Our results show that object in context LTM formation is susceptible to interference by a different and subsequent object-context pair association experienced 1h later. This interference works on the consolidation phase because only affect LTM leaving intact STM expression. Moreover, if the interfered trail occurs 4 h apart the first one, the IR was not observed. Such IR depends on the presentation of another object in context experience, regardless of whether they are familiar or novel. Moreover, this interpolated trail disrupted specifically the consolidation of the object in context memory and did not affect the object recognition memory formation. In addition, we show that the inactivation of the CA1 dorsal hippocampal or mPFC regions, previous to the second trail session, impaired the LTM formation for this trail pair association while restoring the first pair LTM expression. In conclusion our results suggest that object in context LTM formation is suitable of RI by another object in context experience and that requires dorsal Hp and mPFC activity.