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

The stress system coordinates the adaptive reactions of the organism to stressors. Therefore, dys-functions 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 mecha-nisms that underlie these diseases. The central nucleus of the amygdala (CeA) activates thehypothalamic–pituitary–adrenal axis and brainstem nodes by triggering endocrine, autonomic andbehavioral stress responses. The medial prefrontal cortex plays a significant role in regulating reac-tions to stressors, and is specifically important for limiting fear responses. Brain oscillations reflectneural systems activity. Synchronous neuronal assemblies facilitate communication and synapticplasticity, mechanisms that cooperatively support the temporal representation and long-term con-solidation of information. The purpose of this article was to delve into the interactions betweenthese structures in stress contexts by evaluating changes in oscillatory activity. We particularlyanalyzed the local field potential in the infralimbic region of the medial prefrontal cortex (IL) inurethane-anesthetized rats after the electrical activation of the central nucleus of the amygdala bymimicking firing rates induced by acute stress. Electrical CeA activation induced a delayed, but sig-nificant, change in the IL, with prominent slow waves accompanied by an increase in the theta andgamma activities, and spindles. The phase-amplitude coupling of both slow waves and theta oscilla-tions significantly increased with faster oscillations, including theta-gamma coupling and thenesting of spindles, theta and gamma oscillations in the slow wave cycle. These results are furtherdiscussed in neural processing terms of the stress response and memory formation.