Presentation description

The objective of this project is to investigate whether dorsal striatum (DS) neurons encode valence or conditioned behaviors during fear learning and expression. The DS has been shown to play a role in conditioned reward responses, including action selection based on learned associations. This suggests that the DS may also be involved in the selection of specific defensive behaviors such as freezing and darting, which are part of the fear response. Within the DS, there are two major pathways, which correspond to two major cell types: dopamine receptor type 1 (D1) and type 2 (D2) neurons. In the DS, D1 neurons mediate reinforcement of reward associations, while D2 neurons are purported to mediate aversion. The single neuron activity in the dorsal striatum during fear conditioning has never been directly evaluated, and it is unknown whether D1 or D2 DS neurons play a unique role in encoding valence and defensive behaviors. We address this gap in understanding by using in vivo calcium imaging in freely-moving mice to image D2 neuron activity in the DS during the acquisition and expression of cue-conditioned fear responses. Contrasting these responses with neutral and reward-predicting cues allows us to assess valence encoding, sensitization and generalization of conditioned responses in these neurons.