Recruitment of neurons in basolateral amygdala after intense training produces a stronger memory trace

• Published in: Neurobiology of learning and memory Vol. 181; p. 107428
• Main Authors: Ruiz-López, C.X., Medina, A.C., Bello-Medina, P.C., Quirarte, G.L., Prado-Alcalá, R.A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.2021
• Subjects: Animals; Avoidance Learning - physiology; Basolateral amygdala; Basolateral Nuclear Complex - metabolism; Basolateral Nuclear Complex - physiology; c-Fos; Extinction; Extinction, Psychological; Inhibition, Psychological; Inhibitory avoidance; Intense training; Male; Memory - physiology; Neurons - metabolism; Neurons - physiology; Proto-Oncogene Proteins c-fos - metabolism; Rats; Basolateral amygdala; c-Fos; Inhibitory avoidance; Intense training; Extinction
• ISSN: 1074-7427; 1095-9564; 1095-9564
• DOI: 10.1016/j.nlm.2021.107428

•Inhibitory avoidance training activates neurons in basolateral amygdaloid nucleus.•Intense training increases expression of c-Fos in basolateral amygdaloid nucleus.•Memory strength correlates with percentage of c-Fos expressing cells. Typical amnestic treatments are ineffective when administered to subjects trained in aversively-motivated tasks using relatively high foot-shock intensities. This effect has been found when treatments that disrupt neuronal activity are administered to different regions of the brain, including the amygdala. However, the molecular mechanisms induced by this intense training are unknown. We made a detailed mapping of c-Fos-expressing neurons in four regions of the amygdala after moderate and intense one-trial inhibitory avoidance training. Rats were sacrificed 90 min after training or after appropriate control procedures, and their brains were prepared for immunohistochemical c-Fos protein detection in the central, lateral, and in the anterior and posterior parts of the basolateral amygdaloid nucleus. We found a high percentage of neurons expressing c-Fos in the anterior part of the basolateral nucleus after moderate training, and this percentage increased further after intense training. Moderate and intense training did not induce changes in c-Fos expression in the other explored amygdaloid regions. These results show that inhibitory avoidance training produces a localized expression of c-Fos in the basolateral anterior nucleus of the amygdala, which is dependent upon the intensity of training, and indicate that synaptic plastic changes in this region may be required for the formation of memory of moderate and intense aversive learning.