Department of Psychology, Georgia State University, Atlanta, GA, USA; Neuroscience Institute, Georgia State University, Atlanta, GA, USA; Center for Childhood Deafness, Language, and Learning, Boys Town National Research Hospital, Omaha, NE, USA(1).
Department of Psychology, Georgia State University, Atlanta, GA, USA.
Neurobiol Learn Mem. 2020 Mar;169:107175. doi: 10.1016/j.nlm.2020.107175. Epub 2020 Feb 1.
The ability to learn and process sequential dependencies is essential for language acquisition and other cognitive domains. Recent studies suggest that the learning of adjacent (e.g., "A-B") versus nonadjacent (e.g., "A-X-B") dependencies have different cognitive demands, but the neural correlates accompanying such processing are currently underspecified. We developed a sequential learning task in which sequences of printed nonsense syllables containing both adjacent and nonadjacent dependencies were presented. After incidentally learning these grammatical sequences, twenty-one healthy adults (age M = 22.1, 12 females) made familiarity judgments about novel grammatical sequences and ungrammatical sequences containing violations of the adjacent or nonadjacent structure while in a 3T MRI scanner. Violations of adjacent dependencies were associated with increased BOLD activation in both posterior (lateral occipital and angular gyrus) as well as frontal regions (e.g., medial frontal gyrus, inferior frontal gyrus). Initial results indicated no regions showing significant BOLD activations for the violations of nonadjacent dependencies. However, when using a less stringent cluster threshold, exploratory analyses revealed that violations of nonadjacent dependencies were associated with increased activation in subcallosal cortex, paracingulate cortex, and anterior cingulate cortex (ACC). Finally, when directly comparing the adjacent condition to the nonadjacent condition, we found significantly greater levels of activation for the right superior lateral occipital cortex (BA 19) for the adjacent relative to nonadjacent condition. In sum, the detection of violations of adjacent and nonadjacent dependencies appear to involve distinct neural networks, with perceptual brain regions mediating the processing of adjacent but not nonadjacent dependencies. These results are consistent with recent proposals that statistical-sequential learning is not a unified construct but depends on the interaction of multiple neurocognitive mechanisms acting together.
学习和处理顺序依赖性的能力对于语言习得和其他认知领域至关重要。最近的研究表明，学习相邻（例如，“A-B”）和非相邻（例如，“A-X-B”）依赖性具有不同的认知要求，但目前对伴随这种处理的神经相关性还知之甚少。我们开发了一个序列学习任务，其中包含相邻和非相邻依赖性的打印无意义音节序列被呈现。在偶然学习这些语法序列后，二十一名健康成年人（年龄 M=22.1，12 名女性）在 3T MRI 扫描仪中对新的语法序列和包含违反相邻或非相邻结构的不合语法序列进行熟悉度判断。相邻依赖性的违反与后（外侧枕叶和角回）和前（例如，额内侧回、额下回）区域的 BOLD 激活增加有关。最初的结果表明，对于非相邻依赖性的违反，没有显示出显著的 BOLD 激活区域。然而，当使用较不严格的簇阈值进行探索性分析时，发现违反非相邻依赖性与扣带回下皮质、旁中央皮质和前扣带皮层（ACC）的激活增加有关。最后，当直接比较相邻条件和非相邻条件时，我们发现右外侧顶叶上回（BA 19）的激活水平对于相邻条件相对于非相邻条件显著更高。总之，相邻和非相邻依赖性违反的检测似乎涉及不同的神经网络，感知大脑区域介导相邻依赖性但不介导非相邻依赖性的处理。这些结果与最近的建议一致，即统计序列学习不是一个统一的结构，而是取决于多个神经认知机制的相互作用。
