Neural Mechanisms Supporting Differential Auditory Fear Conditioning

Abstract

Pavlovian fear conditioning provides an ideal way to study memory formation, retention, and updating. Plasticity in the auditory thalamus is required during the acquisition and consolidation of a fear memory when a tone signals a foot shock. The medial geniculate nucleus (MgN) of the auditory thalamus sends projections to the amygdala and auditory cortex and is functionally divided into two different regions, the medial division (MGm) and the ventral division (MGv). Traditionally, these divisions are thought to relay auditory information to the amygdala during fear-related associative learning. However, recent research has suggested a more complex role for the MgN when processing auditory stimuli during conditioning. In the current study, we identified synaptic activity necessary for memory formation in the MgN as well as how this plasticity impacts the amygdala. In order to target MgN plasticity, we used a discriminative fear conditioning procedure to recruit auditory thalamus plasticity during conditioning. We predicted that memory consolidation in the MgN requires mRNA translation, which will initiate amygdala receptor trafficking following auditory fear conditioning. We found that protein synthesis in the MgN is required for amygdala AMPA receptor surface expression and synaptic scaffolding necessary for auditory memory consolidation.