Marchand A, Faugère A, Coutureau E, Wolff M
CNRS, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (INCIA), UMR 5287, Avenue des Facultés, 33405, Talence, Cedex, France.
Brain Struct Funct. 2014 Sep;219(5):1575-86. doi: 10.1007/s00429-013-0586-7. Epub 2013 Jun 4.
Understanding the neural processes that govern the attribution of a predictive value to environmental stimuli is a major issue in behavioural neuroscience. The main strategy to explore this question has been the use of Pavlovian fear conditioning paradigms. While a majority of studies have focussed on the specific role of the hippocampus and amygdala in contextual versus cued fear, very few studies examined the potential role of subcortical limbic areas. Among those, the anterior thalamic nuclei (ATN) connect to both the hippocampus and the amygdala and also to the cingulate region which is known to support fear-related activity. Here, we show that rats sustaining ATN lesions exhibit a specific impairment following context but not tone conditioning. ATN lesions slowed down acquisition without preventing normal freezing behaviour when rats were reexposed to the conditioning context 24 h later. However, ATN rats exhibited poor retrieval of contextual but not cued fear when assessed 3 weeks after conditioning. In addition, extinction was faster in ATN rats and spontaneous recovery of contextual fear was impaired by the lesions. These deficits indicate that contextual fear memories established in the absence of the ATN are not robust. Collectively, these findings support an involvement of the ATN in the circuits underlying contextual fear memory.
理解支配环境刺激预测价值归因的神经过程是行为神经科学中的一个主要问题。探索这个问题的主要策略是使用巴甫洛夫恐惧条件反射范式。虽然大多数研究集中在海马体和杏仁核在情境性恐惧与线索性恐惧中的特定作用，但很少有研究考察皮质下边缘区域的潜在作用。其中，前丘脑核（ATN）与海马体和杏仁核相连，也与已知支持恐惧相关活动的扣带回区域相连。在这里，我们表明，遭受ATN损伤的大鼠在情境条件反射而非音调条件反射后表现出特定的损伤。当大鼠在24小时后重新暴露于条件反射情境时，ATN损伤减缓了习得过程，但并未阻止正常的僵住行为。然而，在条件反射3周后评估时，ATN大鼠表现出情境性恐惧的回忆能力较差，但线索性恐惧的回忆能力正常。此外，ATN大鼠的消退速度更快，情境性恐惧的自发恢复也因损伤而受损。这些缺陷表明，在没有ATN的情况下建立的情境性恐惧记忆并不稳固。总的来说，这些发现支持ATN参与情境性恐惧记忆的潜在神经回路。
