Sex steroids such as estrogens and testosterone influence the nervous system in many ways. Which of the following statements about their actions is correct?  雌激素和睾酮等性激素会以多种方式影响神经系统。关于它们的作用，下列哪项陈述是正确的？单项选择题

When acting in neurons, estrogens and testosterone always function independently of gene transcription.   雌激素和睾酮在神经元中发挥作用时，其功能始终独立于基因转录。

Estrogens and testosterone cannot cross the blood-brain barrier, so exert their effects exclusively through peripheral endocrine organs.  雌激素和睾酮不能穿过血脑屏障，因此只能通过外周内分泌器官发挥作用。

Estrogens and testosterone modulate synaptic plasticity and neurotransmitter systems in specific regions of the brain.  雌激素和睾酮调节大脑特定区域的突触可塑性和神经递质系统。

Estrogens and testosterone act on the nervous system only during a short “critical period” that occurs at puberty.  雌激素和睾酮只在青春期短暂的“关键期”内对神经系统起作用。