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Kasugai, Y., Vogel, E., Hortnagl, H. [...] Peterschmitt, Y., [...] Ferraguti, F. (2019)

Structural and Functional Remodeling of Amygdala GABAergic Synapses in Associative Fear Learning

Associative learning is thought to involve differentforms of activity-dependent synaptic plasticity. Although previous studies have mostly focused onlearning-related changes occurring at excitatory glu-tamatergic synapses, we found that associativelearning, such as fear conditioning, also entails long-lasting functional and structural plasticity of GABAergic synapses onto pyramidal neurons of themurine basal amygdala. Fear conditioning-mediatedstructural remodeling of GABAergic synapses was associated with a change in mIPSC kinetics and an increase in the fraction of synaptic benzodiazepine-sensitive (BZD) GABAA receptors containing the α2 subunit without altering the intrasynaptic distributionand overall amount of BZD-GABAA receptors. These structural and functional synaptic changes were partly reversed by extinction training. These findings provide evidence that associative learning, such as Pavlovian fear conditioning and extinction, sculpts inhibitory synapses to regulate inhibition of active neuronal networks, a process that may tune amygdala circuit responses to threats.