Post-training reversible disconnection of the ventral hippocampal–basolateral amygdaloid circuits impairs consolidation of inhibitory avoidance memory in rats

Abstract

The ventral hippocampus (VH) and the basolateral amygdala (BLA) are both crucial in inhibitory avoidance (IA) memory. However, the exact role of the VH-BLA circuit in IA memory consolidation is unclear. This study investigated the effect of post-training reversible disconnection of the VH-BLA circuit in IA memory consolidation. Male Wistar rats with implanted guide cannulae were trained with a one-trial IA task, then received immediate intracerebral injections of muscimol or saline, and were tested 24 h later. Muscimol injection into the bilateral BLA, or the unilateral VH and contralateral BLA, but not the unilateral VH and ipsilateral BLA, significantly decreased the retention latencies (versus saline treatment). The results suggest that the VH-BLA circuit could be an important circuit to modulate consolidation of IA memory in rats.

The role of the hippocampus in the consolidation of emotional memories during sleep

“…Manipulating BLA inputs to the vHPC in mice modulates anxiety-like behaviors, depressive-like behaviors, and fear extinction [61][62][63]. Post-training manipulation of the BLA inputs to the vHPC modulates aversive memory consolidation [64,65]. The BLA neurons projecting to the vHPC encode positive and negative valence in the same proportion [66].…”

The amygdala mediates the facilitating influence of emotions on memory through multiple interacting mechanisms

“…BLA is thought to modulate memory through its downstream targets. For instance, the intermediate/ventral hippocampus receives a prominent projection from the BLA ( Pikkarainen et al, 1999 ), and this pathway has been implicated in memory consolidation ( Wang et al, 2017 ). When rats learn that a specific path on a linear track is associated with an aversive stimulus, coordinated ensembles of BLA and dorsal hippocampal neurons representing that path are re-engaged during post-training SWS ( Girardeau et al, 2017 ).…”

Two Behavioral Tests Allow a Better Correlation Between Cognitive Function and Expression of Synaptic Proteins

“…We administrated in series the Morris water maze (MWM) and the step-through passive avoidance (STPA) tests. We considered these tests suitable to validate/reject our hypothesis for three reasons: (i) together, they allow to assess the performance of both the DH and the VH (Moser et al, 1995 ; Lorenzini et al, 1996 ; Ambrogi Lorenzini et al, 1997 ; Wang et al, 2017 ); (ii) the MWM test is the preferred test for assessing core aspects of spatial learning and memory (Vorhees and Williams, 2014 ), while one-trial inhibitory avoidance is the best studied task concerning the molecular post-training processes of hippocampal cellular memory consolidation (Izquierdo et al, 2016 ); and (iii) evidence exists that spatial and aversive memories, both crucial for a proper interaction with the environment, undergo age-related changes (Lovatel et al, 2013 ; Beaudet et al, 2014 ; Leffa et al, 2014 ).…”