SAME CONTEXT, DIFFERENT OBJECTS, LONG-TERM MEMORY FAILURE IN OBJECT RECOGNITION.

MARÍA EUGENIA VILLAR; PAUL MARCHAL; MARTINEZ MARÍA CECILIA; PAMELA LOPES DA CUNHA; BALLARINI FABRICIO; VIOLA HAYDÉE

Montevideo

Congreso; XII Congress of the International Society for Neuroethology; 2016

With the aim of assessing if object recognition long-term memory (OR-LTM) formation is susceptible to retrograde interference (RI), we submitted rats to two sequential familiarization sessions using the same arena but changing the identity of the pair of objects presented. Separate groups of subjects were tested in order to evaluate the LTM for both objects. We investigated the existence of a RI process, if it could operate within the consolidation window and what kinds of events were able to interfere with OR-LTM. Furthermore, given the involvement of hippocampus (Hp) and medial prefrontal cortex (mPFC) in several recognition memories, we assessed the involvement of these structures inOR-LTM formation by using local infusion of muscimol. Our results suggest that OR-LTM formation is retrograde interfered by a new (but not familiar) object explored in the same arena, within a critical time window. In the test session performed three hour after familiarization, STM expression is not affected but LTM measured 24h after familiarization is impaired, therefore RI acts on the consolidation process. Moreover, local inactivation of the dorsal Hp or mPFC previous to the exploration of the second object pair impaired its LTM consolidation restoring the LTM of the first pair. On the whole, these data suggest that both Hp and mPFC are involved in processing OR tasks which LTM formation is susceptible to RI by the spatial/temporal overlapping of two distinct memory traces consolidations.