Basolateral amygdala projections in the modulation of memory consolidation

Memory is a fundamental capability of our nervous system and a critical part of how we understand ourselves and the world around us. Memory is not monolithic but rather comprises multiple types of memories, however, emotional arousal via the amygdala influences the consolidation of many types of memories. Therefore, it is critical to understand the mechanisms by which the amygdala can separately and dissociably modulate the consolidation of these different types of learning. To that end, my work has investigated how different neural connections from the amygdala to other brain regions influence the consolidation of spatial and cued-response learning in rats. To do so, I have used an optogenetic approach, in which amygdala neurons are transduced to express light-sensitive opsins and then light is applied to amygdala axons in various downstream brain regions immediately after training. The findings from these studies indicate that posttraining optogenetic stimulation of amygdala projections to the entorhinal cortex selectively enhance hippocampus-dependent spatial memory, whereas amygdala projections to the nucleus accumbens are critical for striatum-dependent cued-response memory. Moreover, my findings suggest that the mechanisms for spatial vs. cued-response memory consolidation are, at least sometimes, in competition with one another. Results further suggest that post-spatial training optogenetic stimulation of the amygdala-entorhinal cortex pathway alters the balance of expression of a plasticity-associated protein (ARC) across the hippocampus and striatum. Together, the present work indicates that the ability of the amygdala to influence the consolidation across different types of memory depends on distinct efferent projections and likely via influences on the balance of activity in downstream regions.