Center for Systems Neuroscience, Biology Department, Boston University, Boston, MA, United States of America.
PLoS One. 2023 Apr 17;18(4):e0282349. doi: 10.1371/journal.pone.0282349. eCollection 2023.
Sex hormones can affect cellular physiology and modulate synaptic plasticity, but it is not always clear whether or how sex-dependent differences identified in vitro express themselves as functional dimorphisms in the brain. Historically, most experimental neuroscience has been conducted using only male animals and the literature is largely mute about whether including female mice in will introduce variability due to inherent sex differences or endogenous estrous cycles. Though this is beginning to change following an NIH directive that sex should be included as a factor in vertebrate research, the lack of information raises practical issues around how to design experimental controls and apply existing knowledge to more heterogeneous populations. Various lines of research suggest that visual processing can be affected by sex and estrous cycle stage. For these reasons, we performed a series of in vivo electrophysiological experiments to characterize baseline visual function and experience-dependent plasticity in the primary visual cortex (V1) of male and female mice. We find that sex and estrous stage have no statistically significant effect on baseline acuity measurements, but that both sex and estrous stage have can modulate two mechanistically distinct forms of experience dependent cortical plasticity. We also demonstrate that resulting variability can be largely controlled with appropriate normalizations. These findings suggest that V1 plasticity can be used for mechanistic studies focusing on how sex hormones effect experience dependent plasticity in the mammalian cortex.
性激素会影响细胞生理学并调节突触可塑性，但并不总是清楚体外鉴定的性别依赖性差异是否以及如何表现为大脑中的功能性二态性。从历史上看，大多数实验神经科学仅使用雄性动物进行，而文献中很大程度上没有提到在研究中包括雌性小鼠是否会因内在的性别差异或内源性动情周期而引入变异性。尽管这在 NIH 指令要求将性别作为脊椎动物研究的一个因素之后开始发生变化，但由于缺乏信息，围绕如何设计实验对照以及将现有知识应用于更具异质性的人群，这引发了实际问题。各种研究表明，视觉处理可能会受到性别和动情周期阶段的影响。出于这些原因，我们进行了一系列体内电生理实验，以描述雄性和雌性小鼠初级视觉皮层（V1）的基线视觉功能和经验依赖性可塑性。我们发现，性别和动情周期阶段对基线视力测量没有统计学上的显著影响，但性别和动情周期阶段都可以调节两种机制上不同的经验依赖性皮质可塑性形式。我们还证明，通过适当的归一化可以在很大程度上控制由此产生的可变性。这些发现表明，V1 可塑性可用于研究性激素如何影响哺乳动物皮层中经验依赖性可塑性的机制。
