Groupe d'Imagerie Neurofonctionnelle, UMR CI-NAPS 6232, CNRS CEA, GIP Cyceron, Caen, France.
Neuroimage. 2011 Jan 1;54(1):577-93. doi: 10.1016/j.neuroimage.2010.07.036. Epub 2010 Jul 23.
To evaluate the relative role of left and right hemispheres (RH) and describe the functional anatomy of RH during ortholinguistic tasks, we re-analyzed the 128 papers of a former left-hemisphere (LH) meta-analysis (Vigneau et al., 2006). Of these, 59 articles reported RH participation, providing 105 RH language contrasts including 218 peaks compared to 728 on the left, a proportion reflecting the LH language dominance. To describe inter-hemispheric interactions, in each of the language contrasts involving both hemispheres, we distinguished between unilateral and bilateral peaks, i.e. having homotopic activation in the LH in the same contrast. We also calculated the proportion of bilateral peaks in the LH. While the majority of LH peaks were unilateral (79%), a reversed pattern was observed in the RH; this demonstrates that, in contrast to the LH, the RH works in an inter-hemispheric manner. To analyze the regional pattern of RH participation, these unilateral and bilateral peaks were spatially clustered for each language component. Most RH phonological clusters corresponded to bilateral recruitment of auditory and motor cortices. Notably, the motor representation of the mouth and phonological working memory areas were exclusively left-lateralized, supporting the idea that the RH does not host phonological representations. Right frontal participation was not specific for the language component involved and appeared related to the recruitment of attentional and working memory areas. The fact that RH participation during lexico-semantic tasks was limited to these executive activations is compatible with the hypothesis that active inhibition is exerted from the LH during the processing of meaning. Only during sentence/text processing tasks a specific unilateral RH-temporal involvement was noted, likely related to context processing. These results are consistent with split-brain studies that found that the RH has a limited lexicon, with no phonological abilities but active involvement in the processing of context.
为了评估左、右半球（RH）的相对作用，并描述 RH 在正字法任务中的功能解剖结构，我们重新分析了以前左半球（LH）荟萃分析的 128 篇论文（Vigneau 等人，2006 年）。其中，59 篇文章报道了 RH 的参与情况，提供了 105 个 RH 语言对比，包括 218 个与左侧相比的峰值，这一比例反映了 LH 的语言优势。为了描述半球间的相互作用，在涉及两个半球的每一个语言对比中，我们区分了单侧和双侧的峰值，即在同一对比中具有 LH 同型激活的峰值。我们还计算了 LH 中双侧峰值的比例。虽然大多数 LH 峰值是单侧的（79%），但在 RH 中观察到了相反的模式；这表明，与 LH 相反，RH 以半球间的方式工作。为了分析 RH 参与的区域模式，我们对每个语言成分的单侧和双侧峰值进行了空间聚类。大多数 RH 语音聚类对应于听觉和运动皮层的双侧招募。值得注意的是，口部和语音工作记忆区域的运动代表是专门左侧化的，这支持了 RH 不具有语音代表的观点。右额部参与并不是特定于所涉及的语言成分，而是与注意力和工作记忆区域的招募有关。RH 在词汇语义任务中的参与仅限于这些执行激活的事实与这样一种假设是一致的，即主动抑制是在意义处理过程中由 LH 施加的。只有在句子/文本处理任务中，才注意到特定的单侧 RH-颞叶参与，可能与上下文处理有关。这些结果与裂脑研究一致，裂脑研究发现 RH 的词汇量有限，没有语音能力，但积极参与上下文处理。
