The use of the Emotional-Object Recognition as an assay to assess learning and memory associated to an aversive stimulus in rodents
Journal of Neuroscience Methods. 2016-12-01; 274: 106-115
DOI: 10.1016/j.jneumeth.2016.09.010
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BACKGROUND: Emotionally salient experiences induce the formation of explicit
memory traces, besides eliciting automatic or implicit emotional memory in
rodents. This study aims at investigating the implementation of a novel task for
studying the formation of limbic memory engrams as a result of the acquisition-
and retrieval- of fear-conditioning – biased declarative memory traces, measured
by animal discrimination of an « emotional-object ». Moreover, by using this new
method we investigated the potential interactions between stimulation of
cannabinoid transmission and integration of emotional information and cognitive
functioning.
NEW METHOD: The Emotional-Object Recognition task is composed of 3 following
sessions: habituation; cued fear-conditioned learning; emotional recognition.
Rats are exposed to Context « B chamber » for habituation and cued
fear-conditioning, and tested in Context « A chamber » for emotional-object
recognition.
RESULTS: Cued fear-conditioning induces a reduction in emotional-object
exploration time during the Emotional-Object Recognition task in controls. The
activation of cannabinoid signalling impairs limbic memory formation, with
respect to vehicle.
COMPARISON TO EXISTING METHODS: The Emotional-Object Recognition test overcomes
several limitations of commonly employed methods that explore declarative-,
spatial memory and fear-conditioning in a non-integrated manner. It allows the
assessment of unbiased cognitive indicators of emotional learning and memory.
CONCLUSIONS: The Emotional-Object Recognition task is a valuable tool for
investigating whether, and at what extent, specific drugs or pathological
conditions that interfere with the individual affective/emotional homeostasis,
can modulate the formation of emotionally salient explicit memory traces, thus
jeopardizing control and regulation of animal behavioural strategy.