Govic Antonina, Paolini Antonio G
School of Health Sciences, RMIT University, Bundoora, Victoria, Australia; and
School of Health Sciences, RMIT University, Bundoora, Victoria, Australia; and School of Psychological Science, La Trobe University, Bundoora, Victoria, Australia.
J Neurophysiol. 2015 Mar 1;113(5):1423-36. doi: 10.1152/jn.00373.2014. Epub 2014 Dec 4.
Chemosensory cues signaling predators reliably stimulate innate defensive responses in rodents. Despite the well-documented role of the amygdala in predator odor-induced fear, evidence for the relative contribution of the specific nuclei that comprise this structurally heterogeneous structure is conflicting. In an effort to clarify this we examined neural activity, via electrophysiological recordings, in amygdala subnuclei to controlled and repeated presentations of a predator odor: cat urine. Defensive behaviors, characterized by avoidance, decreased exploration, and increased risk assessment, were observed in adult male hooded Wistar rats (n = 11) exposed to a cloth impregnated with cat urine. Electrophysiological recordings of the amygdala (777 multiunit clusters) were subsequently obtained in freely breathing anesthetized rats exposed to cat urine, distilled water, and eugenol via an air-dilution olfactometer. Recorded units selectively responded to cat urine, and frequencies of responses were distributed differently across amygdala nuclei; medial amygdala (MeA) demonstrated the greatest frequency of responses to cat urine (51.7%), followed by the basolateral and basomedial nuclei (18.8%) and finally the central amygdala (3.0%). Temporally, information transduction occurred primarily from the cortical amygdala and MeA (ventral divisions) to other amygdala nuclei. Interestingly, MeA subnuclei exhibited distinct firing patterns to predator urine, potentially revealing aspects of the underlying neurocircuitry of predator odor processing and defensiveness. These findings highlight the critical involvement of the MeA in processing olfactory cues signaling predator threat and converge with previous studies to indicate that amygdala regulation of predator odor-induced fear is restricted to a particular set of subnuclei that primarily include the MeA, particularly the ventral divisions.
表明存在捕食者的化学感应线索能够可靠地刺激啮齿动物的先天性防御反应。尽管杏仁核在捕食者气味诱发的恐惧中所起的作用已有充分记载，但关于构成这个结构异质结构的特定核团的相对贡献的证据却相互矛盾。为了阐明这一点，我们通过电生理记录，研究了杏仁核亚核在控制性且重复呈现捕食者气味（猫尿）时的神经活动。在暴露于浸有猫尿的布的成年雄性带帽Wistar大鼠（n = 11）中观察到了以回避、探索减少和风险评估增加为特征的防御行为。随后，在通过空气稀释嗅觉计暴露于猫尿、蒸馏水和丁香酚的自由呼吸麻醉大鼠中，获得了杏仁核的电生理记录（777个多单位簇）。记录的单位对猫尿有选择性反应，并且反应频率在杏仁核各核团中的分布不同；内侧杏仁核（MeA）对猫尿的反应频率最高（51.7%），其次是基底外侧核和基底内侧核（18.8%），最后是中央杏仁核（3.0%）。在时间上，信息转导主要从皮质杏仁核和MeA（腹侧部分）传递到其他杏仁核核团。有趣的是，MeA亚核对捕食者尿液表现出不同的放电模式，这可能揭示了捕食者气味处理和防御的潜在神经回路的某些方面。这些发现突出了MeA在处理表明捕食者威胁的嗅觉线索中的关键作用，并与先前的研究一致，表明杏仁核对捕食者气味诱发的恐惧的调节仅限于一组特定的亚核团，主要包括MeA，特别是腹侧部分。
