De Groof Geert, Balthazart Jacques, Cornil Charlotte A, Van der Linden Annemie
Bio-Imaging Laboratory, University of Antwerp, CDE, Universiteitsplein 1, B-2610 Antwerp, Belgium, and.
Research Group in Behavioral Neuroendocrinology, GIGA Neurosciences, University of Liège, B-4000 Liège, Belgium.
J Neurosci. 2017 Apr 19;37(16):4243-4254. doi: 10.1523/JNEUROSCI.1961-16.2017. Epub 2017 Mar 17.
It is increasingly recognized that brain-derived estrogens (neuroestrogens) can regulate brain physiology and behavior much faster than what was previously known from the transcriptional action of estrogens on nuclear receptors. One of the best examples of such neuromodulation by neuroestrogens concerns the acute regulation of sensory coding by the auditory cortex as demonstrated by electrophysiological studies of selected neurons in zebra finches. Yet, the spatial extent of such modulation by neuroestrogens is not known. Using functional magnetic resonance imaging, we demonstrate here that acute estrogen depletion alters within minutes auditory processing in male European starlings. These effects are confined to very specific but large areas of the auditory cortex. They are also specifically lateralized to the left hemisphere. Interestingly, the modulation of auditory responses by estrogens was much larger (both in amplitude and in topography) in March than in December or May/June. This effect was presumably independent from changes in circulating testosterone concentrations since levels of the steroid were controlled by subcutaneous implants, thus suggesting actions related to other aspects of the seasonal cycle or photoperiodic manipulations. Finally, we also show that estrogen production specifically modulates selectivity for behaviorally relevant vocalizations in a specific part of the caudomedial nidopallium. These findings confirm and extend previous conclusions that had been obtained by electrophysiological techniques. This approach provides a new very powerful tool to investigate auditory responsiveness in songbirds and its fast modulation by sex steroids. Neuroestrogens can acutely modulate sensory processing in a manner similar to neuromodulators. We report that acute estrogen depletion rapidly disrupts auditory processing in large areas of the male starling brain. Effects were larger in March than in December or May/June, lateralized to the left hemisphere and specific to behaviorally relevant stimuli. These findings confirm and extend previous data that identified an acute regulation of auditory neurons in zebra finches by (1) delineating the extent of the brain region affected, (2) confirming its lateralization, and (3) demonstrating that a large part of the auditory brain regions are acutely affected by estrogens. These findings provide a very powerful tool to investigate auditory responsiveness in songbirds and its fast modulation by sex steroids.
人们越来越认识到，脑源性雌激素（神经雌激素）对脑生理和行为的调节速度比以前所知的雌激素对核受体的转录作用要快得多。神经雌激素进行这种神经调节的最佳例子之一涉及听觉皮层对感觉编码的急性调节，这在斑胸草雀选定神经元的电生理研究中得到了证实。然而，神经雌激素这种调节的空间范围尚不清楚。我们在此使用功能磁共振成像证明，急性雌激素耗竭在几分钟内就会改变雄性欧洲椋鸟的听觉处理。这些影响局限于听觉皮层非常特定但很大的区域。它们也特别偏向于左半球。有趣的是，雌激素对听觉反应的调节在3月比12月或5/6月要大得多（在幅度和地形图上都是如此）。这种效应可能与循环睾酮浓度的变化无关，因为类固醇水平由皮下植入物控制，因此表明其作用与季节性周期或光周期操纵的其他方面有关。最后，我们还表明，雌激素的产生在尾内侧巢皮质的特定部分特异性地调节对行为相关发声的选择性。这些发现证实并扩展了以前通过电生理技术得出的结论。这种方法为研究鸣禽的听觉反应及其受性类固醇的快速调节提供了一种非常强大的新工具。神经雌激素可以以类似于神经调节剂的方式急性调节感觉处理。我们报告说，急性雌激素耗竭会迅速破坏雄性椋鸟大脑大片区域的听觉处理。3月的影响比12月或5/6月更大，偏向于左半球，并且特定于行为相关刺激。这些发现证实并扩展了以前的数据，这些数据通过（1）描绘受影响的脑区范围，（2）确认其偏向性，以及（3）证明大部分听觉脑区受到雌激素的急性影响，确定了斑胸草雀听觉神经元的急性调节。这些发现为研究鸣禽的听觉反应及其受性类固醇的快速调节提供了一种非常强大的工具。
