Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America.
PLoS One. 2013;8(3):e59857. doi: 10.1371/journal.pone.0059857. Epub 2013 Mar 26.
Male animals often change their behavior in response to the level of competition for mates. Male Lincoln's sparrows (Melospiza lincolnii) modulate their competitive singing over the period of a week as a function of the level of challenge associated with competitors' songs. Differences in song challenge and associated shifts in competitive state should be accompanied by neural changes, potentially in regions that regulate perception and song production. The monoamines mediate neural plasticity in response to environmental cues to achieve shifts in behavioral state. Therefore, using high pressure liquid chromatography with electrochemical detection, we compared levels of monoamines and their metabolites from male Lincoln's sparrows exposed to songs categorized as more or less challenging. We compared levels of norepinephrine and its principal metabolite in two perceptual regions of the auditory telencephalon, the caudomedial nidopallium and the caudomedial mesopallium (CMM), because this chemical is implicated in modulating auditory sensitivity to song. We also measured the levels of dopamine and its principal metabolite in two song control nuclei, area X and the robust nucleus of the arcopallium (RA), because dopamine is implicated in regulating song output. We measured the levels of serotonin and its principal metabolite in all four brain regions because this monoamine is implicated in perception and behavioral output and is found throughout the avian forebrain. After controlling for recent singing, we found that males exposed to more challenging song had higher levels of norepinephrine metabolite in the CMM and lower levels of serotonin in the RA. Collectively, these findings are consistent with norepinephrine in perceptual brain regions and serotonin in song control regions contributing to neuroplasticity that underlies socially-induced changes in behavioral state.
雄性动物通常会根据对配偶的竞争程度改变其行为。雄性林肯麻雀（Melospiza lincolnii）会根据与竞争者歌曲相关的挑战水平，在一周的时间内调节其竞争鸣叫声。歌曲挑战的差异和相关竞争状态的转变应该伴随着神经变化，潜在地在调节感知和歌曲产生的区域。单胺类物质通过调节感知和歌曲产生的区域来介导神经可塑性，以实现行为状态的转变。因此，我们使用高效液相色谱电化学检测法，比较了暴露于被归类为更具挑战性或挑战性较低的歌曲的雄性林肯麻雀的单胺及其代谢物水平。我们比较了听觉端脑的两个感知区域（caudomedial nidopallium 和 caudomedial mesopallium，CMM）中的去甲肾上腺素及其主要代谢物的水平，因为这种化学物质参与调节对歌曲的听觉敏感性。我们还测量了两个歌曲控制核（area X 和 robust nucleus of the arcopallium，RA）中的多巴胺及其主要代谢物的水平，因为多巴胺参与调节歌曲输出。我们测量了四个脑区的 5-羟色胺及其主要代谢物的水平，因为这种单胺类物质参与感知和行为输出，并且存在于整个禽类前脑中。在控制最近的鸣叫后，我们发现，暴露于更具挑战性歌曲的雄性麻雀的 CMM 中去甲肾上腺素代谢物水平较高，RA 中的 5-羟色胺水平较低。总的来说，这些发现与感知脑区中的去甲肾上腺素和歌曲控制区中的 5-羟色胺有助于神经可塑性的形成，而神经可塑性是行为状态的社会诱导变化的基础。
