Positive experience shifts the fear circuit away from the basolateral amygdala — The Association Specialists
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Positive experience shifts the fear circuit away from the basolateral amygdala (22001)

Arvie Rodriguez Abiero 1 , Lauren DiFazio 2 , Zara Greer 2 , Ruiting Jia 2 , Melissa Sharpe 1 2
  1. Department of Psychology, University of Sydney, Camperdown, NSW, Australia
  2. Department of Psychology, University of California, Los Angeles, California, USA

One of the most replicable findings in the behavioural neuroscience literature is that lesions or pharmacological inactivation of the basolateral amygdala (BLA) abolishes the encoding and recall of fear memories. This foundational work in rodents has been replicated in correlative studies in humans. Thus, the basolateral amygdala (BLA) is conceptualised as the brain’s fear center, necessary for formation and storage of fear memories. Yet we recently showed that GABAergic neurons in the lateral hypothalamus (LHGABA) can also become critical for formation of fear memories if rats have had a recent positive experience. That is, LHGABA neurons are not necessary to form fear memories in naïve rats. However, if rats have had a recent positive experience, LHGABA neurons suddenly become necessary to encode the fear memory. Here, we investigated how this recruitment of LHGABA neurons to encode fear memories influences the role of BLA fear memory encoding. Using optogenetic and lesion manipulations of BLA activity, we replicated the existing findings that BLA is necessary for the formation of fear memories in experimentally-naïve rats. However, if rats had a recent positive experience, the BLA was no longer necessary to form the fear memory. Our findings reveal that the recruitment of hypothalamic circuits to encode fear memories shifts the fear memory away from BLA. This begs the question as to the physiological mechanisms underlying this shift in the fear circuit. Together, this work shows that prior experience changes the way we encode memories and suggests a more fluid approach to conceptualising mnemonic processing.