Neuronal Plasticity Induced by Fear Conditioning Is Expressed During Paradoxical Sleep: Evidence From Simultaneous Recordings in the Lateral Amygdala and the Medial Geniculate in Rats

The lateral amygdala (LA) and its afferent connections from the medial geniculate (MG) play a pivotal role in auditory fear conditioning. The authors evaluated whether those neurons could express in paradoxical sleep (PS) physiological plasticity acquired in waking. After a habituation session, rats received tone-footshock pairings in 3 sessions. After each session, the tone alone was presented during PS episodes. Multiunit activity was simultaneously recorded in the LA and the medial part of the MG. Both in LA and MG, conditioned responses emerged rapidly (within 5 trials), were expressed with short latency (