Laureate Institute for Brain Research, Tulsa, OK 74136, USA; University of Tulsa, Oxley College of Health Sciences, Tulsa, OK 74104, USA; University of Iowa, Department of Neurology, Iowa City, IA 52242, USA.
Laureate Institute for Brain Research, Tulsa, OK 74136, USA.
Biol Psychol. 2022 Apr;170:108305. doi: 10.1016/j.biopsycho.2022.108305. Epub 2022 Mar 7.
Although the amygdala plays an important part in the pathogenesis of anxiety and generation of exteroceptive fear, recent discoveries have challenged the directionality of this brain-behavior relationship with respect to interoceptive fear. Here we highlight several paradoxical findings including: (1) amygdala lesion patients who experience excessive fear and panic following inhalation of carbon dioxide (CO), (2) clinically anxious patients who have significantly smaller (rather than larger) amygdalae and a pronounced hypersensitivity toward CO, and (3) epilepsy patients who exhibit apnea immediately following stimulation of their amygdala yet have no awareness that their breathing has stopped. The above findings elucidate an entirely novel role for the amygdala in the induction of apnea and inhibition of CO-induced fear. Such a role is plausible given the strong inhibitory connections linking the central nucleus of the amygdala with respiratory and chemoreceptive centers in the brainstem. Based on this anatomical arrangement, we propose a model of Apnea-induced Anxiety (AiA) which predicts that recurring episodes of apnea are being unconsciously elicited by amygdala activation, resulting in transient spikes in CO that provoke fear and anxiety, and lead to characteristic patterns of escape and avoidance behavior in patients spanning the spectrum of anxiety. If this new conception of AiA proves to be true, and activation of the amygdala can repeatedly trigger states of apnea outside of one's awareness, then it remains possible that the chronicity of anxiety disorders is being interoceptively driven by a chemoreceptive system struggling to maintain homeostasis in the midst of these breathless states.
尽管杏仁核在焦虑症的发病机制和外感受性恐惧的产生中起着重要作用,但最近的发现挑战了这种大脑-行为关系的方向性,涉及内感受性恐惧。在这里,我们强调了一些矛盾的发现,包括:(1)杏仁核损伤患者在吸入二氧化碳(CO)后会经历过度的恐惧和恐慌;(2)临床焦虑患者的杏仁核明显较小(而不是较大),并且对 CO 有明显的超敏反应;(3)癫痫患者在刺激其杏仁核后立即出现呼吸暂停,但没有意识到他们的呼吸已经停止。上述发现阐明了杏仁核对呼吸暂停和抑制 CO 诱导的恐惧的全新作用。鉴于杏仁核的中央核与脑干中的呼吸和化学感受中心之间存在强烈的抑制性连接,这种作用是合理的。基于这种解剖结构,我们提出了一种“呼吸暂停诱导焦虑(AiA)”的模型,该模型预测,反复发生的呼吸暂停是由杏仁核激活无意识地引起的,导致 CO 短暂增加,引起恐惧和焦虑,并导致跨越焦虑谱的患者产生特征性的逃避和回避行为模式。如果 AiA 的这种新概念被证明是正确的,并且杏仁核的激活可以在一个人不知情的情况下反复引发呼吸暂停状态,那么焦虑症的慢性可能是由化学感受系统在这些呼吸暂停状态中努力维持体内平衡所驱动的,这种情况可能会发生。