Environmental enrichment (EE) is known to improve memory and cognition and modulate the impact of aversive stimuli in animals, promoting the development of resilience to stressful situations. Likewise, it is known that EE can modulate synaptic plasticity as is the case of long-term potentiation (LTP). These findings have been described initially in ex vivo preparations, suggesting that the effects of EE are the result of an early modification of the synaptic excitability and transmission. In this regard, it is known that metaplasticity refers to the persistent modification, by previous activity, in the ability to induce synaptic plasticity. Our previous studies have shown that prior training in conditioned taste aversion (CTA) prevents the subsequent induction of LTP in the projection from the basolateral nucleus of the amygdala (Bla) to the insular cortex (IC) in vivo. In addition, we have shown that CTA extinction allows the induction but not the maintenance of IC-LTP of the Bla-IC pathway. Recently, we also showed that prior exposure to environmental enrichment for three weeks reduces the strength of CTA, restoring the brain-derived neurotrophic factor (BDNF) levels in the IC. The present study aimed to analyze the effects of brief exposure to an enriched environment on the strength of aversive memory, as well as on the in vivo IC-LTP. To do so, adult rats were exposed for seven days to an EE, either before CTA training or LTP induction in the Bla-IC pathway. Our results demonstrate that a seven-day exposure to an enriched environment attenuates the aversive response to a strong CTA and allows the induction but not the maintenance of LTP in the insular cortex. These findings provide evidence that metaplastic regulation in a neocortical region takes part in the mechanisms through which brief exposure to enriched environments attenuates an aversive response.

众所周知，环境丰富（EE）可以改善动物的记忆和认知，调节厌恶刺激的影响，促进应激情况恢复能力的发展。同样，众所周知，EE 可以调节突触可塑性，就像长时程增强 (LTP) 的情况一样。这些发现最初是在离体制剂中得到描述的，表明 EE 的作用是突触兴奋性和传递早期改变的结果。在这方面，众所周知，化塑性是指通过先前的活动，诱导突触可塑性的能力的持续改变。我们之前的研究表明，条件性味觉厌恶（CTA）的预先训练可以防止随后在体内从杏仁核基底外侧核（Bla）到岛叶皮质（IC）的投射中诱导LTP。此外，我们还表明，CTA 消光可以诱导但不能维持 Bla-IC 途径的 IC-LTP。最近，我们还表明，预先暴露于浓缩环境三周会降低 CTA 的强度，从而恢复 IC 中的脑源性神经营养因子 (BDNF) 水平。本研究旨在分析短暂暴露于丰富环境对厌恶记忆强度以及体内 IC-LTP 的影响。为此，在 CTA 训练或 Bla-IC 途径中的 LTP 诱导之前，成年大鼠暴露于 EE 7 天。我们的结果表明，暴露在丰富的环境中 7 天可以减弱对强 CTA 的厌恶反应，并且可以诱导但不能维持岛叶皮质中的 LTP。这些发现提供了证据，表明新皮质区域的化生调节参与了短暂暴露于丰富环境中减弱厌恶反应的机制。