Neural oscillations in the infralimbic cortex after electrical stimulation of the amygdala. Relevance to acute stress processing

• Published in: Journal of comparative neurology (1911) Vol. 526; no. 8; pp. 1403 - 1416
• Main Authors: Luque‐García, Aina, Teruel‐Martí, Vicent, Martínez‐Bellver, Sergio, Adell, Albert, Cervera‐Ferri, Ana, Martínez‐Ricós, Joana
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2018
• Subjects: Activity patterns; Afferent Pathways - physiology; Amygdala; Amygdala - physiology; Animals; Anxiety; Autonomic nervous system; Behavioral plasticity; Brain stem; Cerebral Cortex - cytology; Cortex (temporal); Electric Stimulation - methods; Electrical stimuli; Electrophysiological recording; electrophysiology; Ethyl carbamate; Evoked Potentials - physiology; Female; Hypothalamus; Information processing; Memory; Mental depression; Mimicry; Neural plasticity; Neurons - physiology; Pituitary; Prefrontal cortex; rat; Rats; Rats, Sprague-Dawley; RGD Cat# 1566457; RRID:RGD_1566457; RRID:SCR_000903; RRID:SCR_001622; RRID:SCR_001905; stress; Stress response; Synaptic plasticity; Theta rhythms; Time Factors; RGD Cat# 1566457; anxiety; stress; amygdala; RRID:SCR_000903; RRID:SCR_001905; electrophysiology; rat; prefrontal cortex; RRID:SCR_001622; RRID:RGD_1566457
• ISSN: 0021-9967; 1096-9861
• DOI: 10.1002/cne.24416

The stress system coordinates the adaptive reactions of the organism to stressors. Therefore, dysfunctions in this circuit may correlate to anxiety‐related disorders, including depression. Comprehending the dynamics of this network may lead to a better understanding of the mechanisms that underlie these diseases. The central nucleus of the amygdala (CeA) activates the hypothalamic–pituitary–adrenal axis and brainstem nodes by triggering endocrine, autonomic and behavioral stress responses. The medial prefrontal cortex plays a significant role in regulating reactions to stressors, and is specifically important for limiting fear responses. Brain oscillations reflect neural systems activity. Synchronous neuronal assemblies facilitate communication and synaptic plasticity, mechanisms that cooperatively support the temporal representation and long‐term consolidation of information. The purpose of this article was to delve into the interactions between these structures in stress contexts by evaluating changes in oscillatory activity. We particularly analyzed the local field potential in the infralimbic region of the medial prefrontal cortex (IL) in urethane‐anesthetized rats after the electrical activation of the central nucleus of the amygdala by mimicking firing rates induced by acute stress. Electrical CeA activation induced a delayed, but significant, change in the IL, with prominent slow waves accompanied by an increase in the theta and gamma activities, and spindles. The phase‐amplitude coupling of both slow waves and theta oscillations significantly increased with faster oscillations, including theta‐gamma coupling and the nesting of spindles, theta and gamma oscillations in the slow wave cycle. These results are further discussed in neural processing terms of the stress response and memory formation. Interaction between the infralimbic region of the medial prefrontal cortex (IL) and the central nucleus of the amygdala (CeA) is critical in the stress processes. After the electrical activation of the CeA in urethane‐anesthetized rats, by mimicking firing rates induced by acute stress, a delayed particular slow wave in the IL local field potential, in association with theta, gamma and spindles oscillations, was observed. In addition, this slow oscillation was accompanied by an increase in theta‐gamma coupling. This characteristic oscillatory pattern might be a functional substrate to respond to stress and for memory formation.