State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, China.
Department of Brain Cognition and Intelligent Medicine, Beijing University of Posts and Telecommunications, Beijing, China.
Hum Brain Mapp. 2024 Oct 15;45(15):e26713. doi: 10.1002/hbm.26713.
Despite being a relatively new cultural phenomenon, the ability to perform letter-sound integration is readily acquired even though it has not had time to evolve in the brain. Leading theories of how the brain accommodates literacy acquisition include the neural recycling hypothesis and the assimilation-accommodation hypothesis. The neural recycling hypothesis proposes that a new cultural skill is developed by "invading" preexisting neural structures to support a similar cognitive function, while the assimilation-accommodation hypothesis holds that a new cognitive skill relies on direct invocation of preexisting systems (assimilation) and adds brain areas based on task requirements (accommodation). Both theories agree that letter-sound integration may be achieved by reusing pre-existing functionally similar neural bases, but differ in their proposals of how this occurs. We examined the evidence for each hypothesis by systematically comparing the similarities and differences between letter-sound integration and two other types of preexisting and functionally similar audiovisual (AV) processes, namely object-sound and speech-sound integration, by performing an activation likelihood estimation (ALE) meta-analysis. All three types of AV integration recruited the left posterior superior temporal gyrus (STG), while speech-sound integration additionally activated the bilateral middle STG and letter-sound integration directly invoked the AV areas involved in speech-sound integration. These findings suggest that letter-sound integration may reuse the STG for speech-sound and object-sound integration through an assimilation-accommodation mechanism.
尽管是一种相对较新的文化现象，但即使大脑没有时间进化，进行字母-声音整合的能力也很容易获得。关于大脑如何适应读写能力的主要理论包括神经再利用假说和同化-顺应假说。神经再利用假说提出，一种新的文化技能是通过“入侵”预先存在的神经结构来发展的，以支持类似的认知功能，而同化-顺应假说则认为，新的认知技能依赖于预先存在的系统的直接调用（同化），并根据任务要求增加大脑区域（顺应）。这两个理论都认为，字母-声音整合可以通过重复使用预先存在的功能相似的神经基础来实现，但它们在如何实现这一点的建议上存在分歧。我们通过进行激活似然估计 (ALE) 荟萃分析，系统比较字母-声音整合与另外两种预先存在且功能相似的视听 (AV) 过程（即物体-声音和语音-声音整合）之间的异同，来检验每个假设的证据。这三种类型的视听整合都募集了左侧后颞上回 (STG)，而语音-声音整合还额外激活了双侧中颞 STG，而字母-声音整合则直接调用了参与语音-声音整合的视听区域。这些发现表明，字母-声音整合可能通过同化-顺应机制，将 STG 重新用于语音-声音和物体-声音整合。
