Huang Juan, Wu Xihong, Yeomans John, Li Liang
Department of Psychology, Speech and Hearing Research Center, National Key Laboratory on Machine Perception, Peking University, Beijing, 100871, China.
Eur J Neurosci. 2005 Apr;21(7):1943-56. doi: 10.1111/j.1460-9568.2005.04030.x.
The amygdala mediates both emotional learning and fear potentiation of startle. The lateral amygdala nucleus (LA) receives auditory inputs from both the auditory thalamus (medial geniculate nucleus; MGN) and auditory association cortex (AAC), and is critical for auditory fear conditioning. The central amygdala nucleus, which has intra-amygdaloid connections with LA, enhances startle magnitude via midbrain connections to the startle circuits. Tetanic stimulation of either MGN or AAC in vitro or in vivo can induce long-term potentiation in LA. In the present study, behavioural consequences of tetanization of these auditory afferents were investigated in awake rats. The acoustic startle reflex of rats was enhanced by tetanic stimulation of MGN, but suppressed by that of AAC. All the tetanization-induced changes of startle diminished within 24 h. Blockade of GABAB receptors in the LA area reversed the suppressive effect of tetanic stimulation of AAC on startle but did not change the enhancing effect of tetanic stimulation of MGN. Moreover, transient electrical stimulation of MGN enhanced the acoustic startle reflex when it lagged behind acoustic stimulation, but inhibited the acoustic startle reflex when it preceded acoustic stimulation. The results of the present study indicate that MGN and AAC afferents to LA play different roles in emotional modulation of startle, and AAC afferents are more influenced by inhibitory GABAB transmission in LA.
杏仁核介导情绪学习和惊吓恐惧增强。外侧杏仁核核团（LA）接收来自听觉丘脑（内侧膝状体核；MGN）和听觉联合皮层（AAC）的听觉输入，并且对听觉恐惧条件反射至关重要。与LA有杏仁核内连接的中央杏仁核核团，通过与惊吓回路的中脑连接增强惊吓幅度。在体外或体内对MGN或AAC进行强直刺激可在LA诱导长时程增强。在本研究中，在清醒大鼠中研究了这些听觉传入纤维强直刺激的行为后果。对MGN进行强直刺激可增强大鼠的听觉惊吓反射，但对AAC进行强直刺激则抑制该反射。所有强直刺激引起的惊吓变化在24小时内消失。阻断LA区域的GABAB受体可逆转对AAC进行强直刺激对惊吓的抑制作用，但不改变对MGN进行强直刺激的增强作用。此外，当MGN的短暂电刺激滞后于声音刺激时，可增强听觉惊吓反射，但当它先于声音刺激时，则抑制听觉惊吓反射。本研究结果表明，LA的MGN和AAC传入纤维在惊吓的情绪调节中发挥不同作用，并且AAC传入纤维受LA中抑制性GABAB传递的影响更大。
