The Brain-Derived Neurotrophic Factor (BDNF) polymorphism, specifically the Val66Met single-nucleotide polymorphism, has significant effects on extinction learning in both mice and humans. This variant influences the brain's capacity to learn from past experiences and adjust behavior based on changing environments. Here's what the research indicates:

1. In Mice:

   • Mice homozygous for the BDNF Val66Met polymorphism exhibit reduced extinction learning, which continues from adolescence into adulthood. These mice show impaired ability to extinguish conditioned fear responses during extinction trials source.

2. In Humans:

   • Humans with the Met allele of the BDNF Val66Met polymorphism also display impaired extinction learning. This polymorphism is associated with atypical frontoamygdala activity when attempting to extinguish fear responses, suggesting a potential link to anxiety disorders source.
   • There is evidence that such genetic variants may play a role in the efficacy of treatments, like exposure-based Cognitive Behavioral Therapy (CBT), which rely on extinction mechanisms source.

3. General Implications:

   • The BDNF Val66Met polymorphism leads to diminished synaptic plasticity, impacting learning and memory processes. This has broader implications for the treatment of anxiety-related behavior and disorders, as understanding this polymorphism can help tailor more effective therapeutic approaches source.

Here are some relevant images that illustrate these findings:

In conclusion, the BDNF Val66Met polymorphism significantly affects extinction learning and represents a crucial factor in both animal models and humans, with substantial implications for understanding and treating anxiety disorders.