Perry Christina J, John Ricky, Trinh Han B, Richards Brandon K, Drummond Katherine D, Park Chun Hui J, Kim Jee Hyun
School of Psychological Sciences, Centre for Emotional Health, Macquarie University, North Ryde, NSW, Australia.
Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia.
Front Behav Neurosci. 2025 Oct 22;19:1636674. doi: 10.3389/fnbeh.2025.1636674. eCollection 2025.
Latent inhibition is diminished associative memory because of pre-exposure to the conditioned stimulus without any consequences. Latent inhibition likely plays a significant role in the ontogeny of anxiety disorders, contributing to why anxiety disorders are particularly prevalent in adolescence. Therefore, the present study examined latent inhibition of conditioned fear in adolescent and adult rats of each sex. Given that adolescence is associated with deficits in fear extinction, we hypothesized that latent inhibition will be impaired in adolescents compared to adults and expected females to show age-specific estrous cycle effects.
On day 1, male (Experiment 1) and female (Experiment 2) rats were placed in fear conditioning chambers. Half of the rats received pre-exposure to the tone cue while the other half received nothing. On day 2, all rats were placed back in the same chambers and exposed to three cue-footshock pairings. Latent inhibition was tested on day 3 with 20 presentations of the cue by itself in the same chamber.
We unexpectedly observed enhanced latent inhibition in adolescents compared to adults in both male and female rats, indicated by lower levels of freezing due to pre-exposure to the cue. Estrous cycle did not affect latent inhibition at any age.
These results suggest that benign experience to a cue reduces subsequent conditioning to the cue more potently in adolescence compared to adulthood, which suggests a potential resilience mechanism naturally occurring in adolescence.
潜伏抑制是指由于对条件刺激进行了无任何后果的预先暴露而导致的联想记忆减弱。潜伏抑制可能在焦虑症的个体发生中起重要作用，这有助于解释为什么焦虑症在青少年中尤为普遍。因此，本研究考察了各性别青少年和成年大鼠的条件性恐惧潜伏抑制情况。鉴于青春期与恐惧消退缺陷有关，我们假设与成年大鼠相比，青少年大鼠的潜伏抑制会受损，并预期雌性大鼠会表现出特定年龄的发情周期效应。
在第1天，将雄性（实验1）和雌性（实验2）大鼠置于恐惧条件反射箱中。一半大鼠接受对音调线索的预先暴露，而另一半则不接受任何处理。在第2天，所有大鼠被放回同一箱中，并接受三次线索-足底电击配对。在第3天，通过在同一箱中单独呈现20次线索来测试潜伏抑制。
我们意外地观察到，与成年大鼠相比，青少年大鼠在潜伏抑制方面增强，这表现为由于预先暴露于线索而导致的僵立水平较低。发情周期在任何年龄都不影响潜伏抑制。
这些结果表明，与成年期相比，青春期对线索的良性体验更有效地减少了随后对该线索的条件反射，这表明青春期自然存在一种潜在的恢复机制。
