Paolini Antonio G, Morgan Simeon J, Kim Jee Hyun
ISN Psychology, Institute for Social Neuroscience, Ivanhoe 3087, Australia.
School of Psychology and Public Health, La Trobe University, Bundoora 3086, Australia.
Neuronal Signal. 2020 Nov 16;4(4):NS20200009. doi: 10.1042/NS20200009. eCollection 2020 Dec.
Anxiety disorders involve distorted perception of the world including increased saliency of stress-associated cues. However, plasticity in the initial sensory regions of the brain following a fearful experience has never been examined. The cochlear nucleus (CN) is the first station in the central auditory system, with heterogeneous collections of neurons that not only project to but also receive projections from cortico-limbic regions, suggesting a potential for experience-dependent plasticity. Using wireless neural recordings in freely behaving rats, we demonstrate for the first time that neural gain in the CN is significantly altered by fear conditioning to auditory sequences. Specifically, the ventral subnuclei significantly increased firing rate to the conditioned tone sequence, while the dorsal subnuclei significantly decreased firing rate during the conditioning session overall. These findings suggest subregion-specific changes in the balance of inhibition and excitation in the CN as a result of conditioning experience. Heart rate was measured as the conditioned response (CR), which showed that while pre-conditioned stimulus (CS) responding did not change across baseline and conditioning sessions, significant changes in heart rate were observed to the tone sequence followed by shock. Heart-rate findings support acquisition of conditioned fear. Taken together, the present study presents first evidence for potential experience-dependent changes in auditory perception that involve novel plasticity within the first site of processing auditory information in the brain.
焦虑症涉及对世界的扭曲认知，包括与压力相关线索的显著性增加。然而，恐惧经历后大脑初始感觉区域的可塑性从未被研究过。耳蜗核（CN）是中枢听觉系统的第一站，其神经元种类多样，不仅投射到皮质-边缘区域，还接收来自该区域的投射，这表明其具有依赖经验的可塑性潜力。通过对自由活动大鼠进行无线神经记录，我们首次证明，对听觉序列进行恐惧条件反射会显著改变耳蜗核的神经增益。具体而言，腹侧亚核对条件化音调序列的放电率显著增加，而在整个条件化过程中，背侧亚核的放电率显著降低。这些发现表明，由于条件化经历，耳蜗核中抑制和兴奋平衡发生了亚区域特异性变化。测量心率作为条件反应（CR），结果显示，虽然在基线期和条件化期对条件前刺激（CS）的反应没有变化，但对随后伴有电击的音调序列观察到心率有显著变化。心率结果支持了条件性恐惧的习得。综上所述，本研究首次提供了证据，表明听觉感知中可能存在依赖经验的变化，这种变化涉及大脑中处理听觉信息的首个部位的新型可塑性。
