Assignment of valence, positive or negative, to external stimuli is essential to the formation of emotional responses. Information pertaining to an animal’s emotional state serve as critical components of memories. However, the neural circuits which govern the valence representations, and which modulate the balance of their dynamic interactions are barely known. I will our recent advances in understanding the valence encoding and emotional memories in amygdala circuits. We identified genetically-distinct neuronal populations in the central amygdala (CeA) and characterized their functional contributions towards valence-specific behaviors. Using cell-type specific approaches, we dissected a basolateral amygdala (BLA)-to-CeA circuit that promotes and suppresses appetitive behaviors. This intra-amygdalar circuit motif reveals an organizing principle of genetic-specific representation of positive and negative valence in the mammalian brain. Next, we sought to examine the role of positive and negative neurons in control of fear memory. Using the engram-identification technique, we demonstrated that fear extinction memory is formed and stored in a genetically-defined population of BLA neurons that also drives reward behaviors and antagonizes BLA’s fear neurons. The fear extinction engram cells and reward neurons are equivalent with regard to their neuronal representations within the BLA and their functions in driving appetitive functions and fear extinction behaviors. Thus, fear extinction is a newly formed reward memory. Collectively, our work sheds light on the cellular and circuit mechanisms underlying valence encoding and memories in the amygdala, and offers implications for developing therapeutic targets for emotional disorders, such as post-traumatic syndrome disorders (PTSD).

Location: Zoom Meeting
Contact: Aimee Schroeder aimeesch@mit.edu
               Kaytee Flick kayteeflick@gmail.com

Thesis Supervisor: Susumu Tonegawa
Join Zoom Meeting: https://mit.zoom.us/j/7386985279
Meeting ID: 738-698-5279