Department of Psychology and Logopedics, University of Helsinki, Helsinki, Finland.
Department of Psychology and Logopedics, University of Helsinki, Helsinki, Finland; Department of Neuroscience, Georgetown University, Washington D.C., USA.
Brain Res. 2022 Jan 15;1775:147739. doi: 10.1016/j.brainres.2021.147739. Epub 2021 Nov 26.
Selective listening to speech depends on widespread networks of the brain, but how the involvement of different neural systems in speech processing is affected by factors such as the task performed by a listener and speech intelligibility remains poorly understood. We used functional magnetic resonance imaging to systematically examine the effects that performing different tasks has on neural activations during selective attention to continuous audiovisual speech in the presence of task-irrelevant speech. Participants viewed audiovisual dialogues and attended either to the semantic or the phonological content of speech, or ignored speech altogether and performed a visual control task. The tasks were factorially combined with good and poor auditory and visual speech qualities. Selective attention to speech engaged superior temporal regions and the left inferior frontal gyrus regardless of the task. Frontoparietal regions implicated in selective auditory attention to simple sounds (e.g., tones, syllables) were not engaged by the semantic task, suggesting that this network may not be not as crucial when attending to continuous speech. The medial orbitofrontal cortex, implicated in social cognition, was most activated by the semantic task. Activity levels during the phonological task in the left prefrontal, premotor, and secondary somatosensory regions had a distinct temporal profile as well as the highest overall activity, possibly relating to the role of the dorsal speech processing stream in sub-lexical processing. Our results demonstrate that the task type influences neural activations during selective attention to speech, and emphasize the importance of ecologically valid experimental designs.
选择性聆听言语依赖于大脑广泛的网络，但执行听众的任务以及言语可懂度等因素如何影响言语处理中不同神经系统的参与程度仍知之甚少。我们使用功能磁共振成像系统地研究了在存在与任务不相关的言语的情况下，执行不同任务对选择性注意连续视听言语期间神经激活的影响。参与者观看视听对话，并专注于言语的语义或音韵内容，或完全忽略言语并执行视觉控制任务。这些任务与良好和较差的听觉和视觉言语质量进行了析因组合。无论任务如何，选择性注意言语都会激活颞上区域和左侧额下回。与简单声音（例如音高、音节）的选择性听觉注意有关的额顶叶区域不受语义任务的影响，这表明当注意力集中在连续言语上时，该网络可能并不那么重要。与社会认知有关的内侧眶额皮层在语义任务中被激活的程度最高。在左前额叶、运动前和次级体感区域执行音韵任务期间的活动水平具有独特的时间分布，以及最高的总体活动水平，这可能与背侧言语处理流在亚词汇处理中的作用有关。我们的研究结果表明，任务类型会影响选择性注意言语时的神经激活，强调了生态有效实验设计的重要性。
