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The sympathetic nervous system originates in the spinal cord and its main function is to activate the arousal responses that occur during the fight-or-flight response. [13] The sympathetic nervous system transfers signals from the dorsal hypothalamus, which activates the heart, increases vascular resistance, and increases blood flow, especially ...
In fear conditioning, the main circuits that are involved are the sensory areas that process the conditioned and unconditioned stimuli, certain regions of the amygdala that undergo plasticity (or long-term potentiation) during learning, and the regions that bear an effect on the expression of specific conditioned responses.
In 1995, rage was hypothesized to occur when oxytocin, vasopressin, and corticotropin-releasing hormone are rapidly released from the hypothalamus. This results in the pituitary gland producing and releasing large amounts of the adrenocorticotropic hormone, which causes the adrenal cortex to release corticosteroids. This chain reaction occurs ...
These hormones are released into the blood in the posterior pituitary. [10] Much smaller parvocellular neurosecretory cells , neurons of the paraventricular nucleus, release corticotropin-releasing hormone and other hormones into the hypophyseal portal system , where these hormones diffuse to the anterior pituitary .
Some of the hormones involved during the state of fight-or-flight include epinephrine, which regulates heart rate and metabolism as well as dilating blood vessels and air passages, norepinephrine increasing heart rate, blood flow to skeletal muscles and the release of glucose from energy stores, [55] and cortisol which increases blood sugar ...
Norepinephrine release is lowest during sleep, rises during wakefulness, and reaches much higher levels during situations of stress or danger, in the so-called fight-or-flight response. In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and focuses attention; it also ...
Corticotropin-releasing hormone (CRH) (also known as corticotropin-releasing factor (CRF) or corticoliberin; corticotropin may also be spelled corticotrophin) is a peptide hormone involved in stress responses. It is a releasing hormone that belongs to corticotropin-releasing factor family. In humans, it is encoded by the CRH gene. [5]
The central nuclei are involved in the genesis of many fear responses such as defensive behavior (freezing or escape responses), autonomic nervous system responses (changes in blood pressure and heart rate/tachycardia), neuroendocrine responses (stress-hormone release), etc. Damage to the amygdalae impairs both the acquisition and expression of ...