Sabri Merav, Binder Jeffrey R, Desai Rutvik, Medler David A, Leitl Michael D, Liebenthal Einat
Medical College of Wisconsin, Department of Neurology, MEB 4550, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
Neuroimage. 2008 Feb 1;39(3):1444-56. doi: 10.1016/j.neuroimage.2007.09.052. Epub 2007 Oct 11.
The role of attention in speech comprehension is not well understood. We used fMRI to study the neural correlates of auditory word, pseudoword, and nonspeech (spectrally rotated speech) perception during a bimodal (auditory, visual) selective attention task. In three conditions, Attend Auditory (ignore visual), Ignore Auditory (attend visual), and Visual (no auditory stimulation), 28 subjects performed a one-back matching task in the assigned attended modality. The visual task, attending to rapidly presented Japanese characters, was designed to be highly demanding in order to prevent attention to the simultaneously presented auditory stimuli. Regardless of stimulus type, attention to the auditory channel enhanced activation by the auditory stimuli (Attend Auditory>Ignore Auditory) in bilateral posterior superior temporal regions and left inferior frontal cortex. Across attentional conditions, there were main effects of speech processing (word+pseudoword>rotated speech) in left orbitofrontal cortex and several posterior right hemisphere regions, though these areas also showed strong interactions with attention (larger speech effects in the Attend Auditory than in the Ignore Auditory condition) and no significant speech effects in the Ignore Auditory condition. Several other regions, including the postcentral gyri, left supramarginal gyrus, and temporal lobes bilaterally, showed similar interactions due to the presence of speech effects only in the Attend Auditory condition. Main effects of lexicality (word>pseudoword) were isolated to a small region of the left lateral prefrontal cortex. Examination of this region showed significant word>pseudoword activation only in the Attend Auditory condition. Several other brain regions, including left ventromedial frontal lobe, left dorsal prefrontal cortex, and left middle temporal gyrus, showed Attention x Lexicality interactions due to the presence of lexical activation only in the Attend Auditory condition. These results support a model in which neutral speech presented in an unattended sensory channel undergoes relatively little processing beyond the early perceptual level. Specifically, processing of phonetic and lexical-semantic information appears to be very limited in such circumstances, consistent with prior behavioral studies.
注意力在言语理解中的作用尚未得到充分理解。我们使用功能磁共振成像（fMRI）来研究在双模态（听觉、视觉）选择性注意力任务期间，听觉单词、假词和非言语（频谱旋转语音）感知的神经关联。在三种条件下，即“关注听觉（忽略视觉）”、“忽略听觉（关注视觉）”和“视觉（无听觉刺激）”，28名受试者在指定的关注模态下执行了一个1-back匹配任务。视觉任务是关注快速呈现的日文字符，其设计要求很高，以防止对同时呈现的听觉刺激的关注。无论刺激类型如何，对听觉通道的注意力增强了双侧后颞上区和左额下回皮质中听觉刺激的激活（关注听觉>忽略听觉）。在所有注意力条件下，左眶额皮质和几个右半球后部区域存在言语处理的主效应（单词+假词>旋转语音），尽管这些区域也显示出与注意力的强烈交互作用（在关注听觉条件下的言语效应大于忽略听觉条件），并且在忽略听觉条件下没有显著的言语效应。其他几个区域，包括中央后回、左缘上回和双侧颞叶，仅在关注听觉条件下由于存在言语效应而显示出类似的交互作用。词汇性的主效应（单词>假词）局限于左侧前额叶皮质的一个小区域。对该区域的检查显示，仅在关注听觉条件下存在显著的单词>假词激活。其他几个脑区，包括左腹内侧额叶、左背外侧前额叶皮质和左颞中回，仅在关注听觉条件下由于存在词汇激活而显示出注意力×词汇性的交互作用。这些结果支持了一个模型，即在未被关注的感觉通道中呈现的中性言语在早期感知水平之外接受的处理相对较少。具体而言，在这种情况下，语音和词汇语义信息的处理似乎非常有限，这与先前的行为研究一致。
