Doctoral Dissertation Improvement Grant: Lateralization of Tool Making and Language in the Brain

这个博士论文项目研究了利手性和大脑功能组织之间的关系，特别是在语言和工具制造方面。最近对石器制造的脑成像研究结果表明，类似的大脑网络在工具制造和语言制造中都很活跃，这导致了关于人类谱系中语言和技术共同进化的假设。可能与这些假设相关的一种未被探索的行为是人类的利手性特征。超过85%的人类是右撇子，而惯用手与大脑组织有关，特别是与语言、工具制造和其他重要行为有关。一些人认为，追踪整个群体对右手偏好的进化可能有助于理解其他重要特征在群体水平上的变化，因为惯用手的进化可以作为大脑半球专业化进化的代表。然而，研究人员需要确保利手性与现代人的大脑功能活动密切相关，特别是在语言和工具制造方面，以确保这种代理关系适用于考古记录。博士生将收集人类参与者（50%是左撇子）的神经成像数据，这些参与者将在进行功能性磁共振成像（fMRI）扫描的同时完成石器制作、语言和视觉空间任务。在接受扫描之前，参与者将完成几项对惯用手的评估，并学习制作简单的石器。这将是第一次在石器工具制造神经成像的背景下对左撇子进行研究，也是第一次比较石器工具制造对同一参与者的语言和视觉空间注意力的大脑网络。需要回答的具体问题是：(1)哪种方法最适合描述参与者的惯用手行为（行为测量、调查，还是两者的混合）？(2)在石器制作、语言和空间技能方面是否有共同的大脑活动区域（以及在哪个半球）？(3)这些任务的半球专业化是否与参与者的利手性有关？这项研究对那些研究人类利手性进化的人有明确的意义，但它对人类认知和语言进化的更广泛讨论也很重要。直接表明利手性与这些行为的功能性大脑活动相对应，将为研究它们的进化背景和历史提供进一步的动力。如果可以建立可靠的方法来确定骨骼遗骸和石器组合中的手性，研究人员可以对人类祖先及其行为做出更明智的解释。如果利手性与工具制造和语言的大脑网络不一致，那么对技术、语言和认知进化感兴趣的研究人员可以将注意力集中在其他主题上进行未来的研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This doctoral dissertation project examines the relationship between handedness and functional brain organization, specifically for language and toolmaking. Results from recent brain imaging studies on stone tool manufacture show that similar brain networks are active for toolmaking and language, leading to hypotheses about the co-evolution of language and technology in the human lineage. One unexplored behavior that may be relevant to these hypotheses is the human trait of handedness. Over 85% of living humans are right-handed, and handedness has been shown to relate to brain organization specifically for language, toolmaking, and other important behaviors. Some have argued that tracking the evolution of population-wide right-hand preference may help to understand population-level changes in other important traits, as handedness evolution can be used as a proxy for the evolution of hemispheric specialization in the brain. However, researchers need to be sure that handedness associates well with functional brain activity in modern humans, specifically for language and toolmaking, to make sure this proxy relationship is applicable to the archaeological record. The doctoral student will collect neuroimaging data from human participants (50% left-handed) who will complete stone toolmaking, language, and visuospatial tasks while undergoing functional Magnetic Resonance Imaging (fMRI) scanning. Before being scanned, participants will complete several assessments of handedness and also learn to make simple stone tools. This will be the first study of left-handers within the context of stone tool making neuroimaging, and it will also be the first comparison of brain networks underlying stone toolmaking to both language and visuospatial attention in the same participants. The specific questions to be answered are: (1) Which methods are best for characterizing participant handedness (behavioral measures, surveys, or a mix of both)? (2) Are there common brain areas active for stone toolmaking, language, and spatial skills (and in which hemisphere)? (3) Does hemispheric specialization for these tasks associate with participant handedness? This study has clear implications for those who study the evolution of handedness in hominins, but it is also significant for wider discussions on the evolution of human cognition and language. Directly showing that handedness corresponds to functional brain activity for these behaviors will provide further motivation to examine their evolutionary contexts and histories. If reliable methods can be established for determining handedness in skeletal remains and stone tool assemblages researchers can make more informed interpretations about human ancestors and their behaviors. If handedness does not correspond to brain networks for toolmaking and language, researchers interested in the evolution of technology, language, and cognition can focus on other topics for future research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.