Markham Rebecca G, Shimizu Toru, Lickliter Robert
Department of Psychology, University of Texas, Austin, Texas 78712, USA.
Dev Neurobiol. 2008 Nov;68(13):1463-73. doi: 10.1002/dneu.20667.
Embryonic vision is generated and maintained by spontaneous neuronal activation patterns, yet extrinsic stimulation also sculpts sensory development. Because the sensory and motor systems are interconnected in embryogenesis, how extrinsic sensory activation guides multimodal differentiation is an important topic. Further, it is unknown whether extrinsic stimulation experienced near sensory sensitivity onset contributes to persistent brain changes, ultimately affecting postnatal behavior. To determine the effects of extrinsic stimulation on multimodal development, we delivered auditory stimulation to bobwhite quail groups during early, middle, or late embryogenesis, and then tested postnatal behavioral responsiveness to auditory or visual cues. Auditory preference tendencies were more consistently toward the conspecific stimulus for animals stimulated during late embryogenesis. Groups stimulated during middle or late embryogenesis showed altered postnatal species-typical visual responsiveness, demonstrating a persistent multimodal effect. We also examined whether auditory-related brain regions are receptive to extrinsic input during middle embryogenesis by measuring postnatal cellular activation. Stimulated birds showed a greater number of ZENK-immunopositive cells per unit volume of brain tissue in deep optic tectum, a midbrain region strongly implicated in multimodal function. We observed similar results in the medial and caudomedial nidopallia in the telencephalon. There were no ZENK differences between groups in inferior colliculus or in caudolateral nidopallium, avian analog to prefrontal cortex. To our knowledge, these are the first results linking extrinsic stimulation delivered so early in embryogenesis to changes in postnatal multimodal behavior and cellular activation. The potential role of competitive interactions between the sensory and motor systems is discussed.
胚胎视觉由自发的神经元激活模式产生并维持，但外部刺激也塑造了感觉发育。由于感觉系统和运动系统在胚胎发生过程中相互连接，外部感觉激活如何引导多模态分化是一个重要的课题。此外，在感觉敏感性开始出现时所经历的外部刺激是否会导致大脑的持续变化，最终影响出生后的行为，这一点尚不清楚。为了确定外部刺激对多模态发育的影响，我们在胚胎发育的早期、中期或晚期对北美鹑组进行听觉刺激，然后测试出生后对听觉或视觉线索的行为反应性。对于在胚胎发育晚期受到刺激的动物，听觉偏好倾向更一致地指向同种刺激。在胚胎发育中期或晚期受到刺激的组表现出出生后物种典型视觉反应性的改变，这表明存在持续的多模态效应。我们还通过测量出生后的细胞激活情况，研究了在胚胎发育中期与听觉相关的脑区是否接受外部输入。受刺激的鸟类在深视顶盖（一个与多模态功能密切相关的中脑区域）每单位体积的脑组织中显示出更多的ZENK免疫阳性细胞。我们在端脑的内侧和尾内侧巢皮质中观察到了类似的结果。在下丘或尾外侧巢皮质（鸟类前额叶皮质的类似物）中，各组之间的ZENK没有差异。据我们所知，这些是将胚胎发育早期给予的外部刺激与出生后多模态行为和细胞激活变化联系起来的首批结果。文中还讨论了感觉系统和运动系统之间竞争性相互作用的潜在作用。
