Biological Psychology, Department of Psychology, Department for Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany; Cluster of Excellence "Hearing4all", Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
Biological Psychology, Department of Psychology, Department for Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany; Cluster of Excellence "Hearing4all", Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
Neuroimage. 2018 Jul 15;175:425-437. doi: 10.1016/j.neuroimage.2018.04.023. Epub 2018 Apr 12.
Hearing loss is associated with difficulties in understanding speech, especially under adverse listening conditions. In these situations, seeing the speaker improves speech intelligibility in hearing-impaired participants. On the neuronal level, previous research has shown cross-modal plastic reorganization in the auditory cortex following hearing loss leading to altered processing of auditory, visual and audio-visual information. However, how reduced auditory input effects audio-visual speech perception in hearing-impaired subjects is largely unknown. We here investigated the impact of mild to moderate age-related hearing loss on processing audio-visual speech using functional magnetic resonance imaging. Normal-hearing and hearing-impaired participants performed two audio-visual speech integration tasks: a sentence detection task inside the scanner and the McGurk illusion outside the scanner. Both tasks consisted of congruent and incongruent audio-visual conditions, as well as auditory-only and visual-only conditions. We found a significantly stronger McGurk illusion in the hearing-impaired participants, which indicates stronger audio-visual integration. Neurally, hearing loss was associated with an increased recruitment of frontal brain areas when processing incongruent audio-visual, auditory and also visual speech stimuli, which may reflect the increased effort to perform the task. Hearing loss modulated both the audio-visual integration strength measured with the McGurk illusion and brain activation in frontal areas in the sentence task, showing stronger integration and higher brain activation with increasing hearing loss. Incongruent compared to congruent audio-visual speech revealed an opposite brain activation pattern in left ventral postcentral gyrus in both groups, with higher activation in hearing-impaired participants in the incongruent condition. Our results indicate that already mild to moderate hearing loss impacts audio-visual speech processing accompanied by changes in brain activation particularly involving frontal areas. These changes are modulated by the extent of hearing loss.
听力损失与理解言语的困难有关，尤其是在不利的听力条件下。在这些情况下，看到说话者可以提高听力受损参与者的言语可懂度。在神经元水平上，先前的研究表明，听力损失后听觉皮层会发生跨模态的可塑性重组，导致听觉、视觉和视听信息的处理方式发生改变。然而，听力受损者的听觉输入减少如何影响视听言语感知，在很大程度上尚不清楚。我们在这里使用功能磁共振成像研究了轻度至中度与年龄相关的听力损失对视听言语处理的影响。正常听力和听力受损的参与者进行了两项视听言语整合任务：在扫描仪内进行句子检测任务和在扫描仪外进行 McGurk 错觉任务。这两个任务都包含一致和不一致的视听条件，以及仅听觉和仅视觉条件。我们发现听力受损参与者的 McGurk 错觉明显更强，这表明更强的视听整合。神经上，当处理不一致的视听、听觉和视觉言语刺激时，听力损失与额区大脑区域的募集增加有关，这可能反映出完成任务的难度增加。听力损失调节 McGurk 错觉测量的视听整合强度以及句子任务中额区的大脑激活，随着听力损失的增加，整合增强，大脑激活增加。与一致的视听言语相比，不一致的视听言语在两组中都显示出左腹侧后中央回的相反大脑激活模式，听力受损组在不一致条件下的激活更高。我们的结果表明，即使是轻度至中度的听力损失也会影响视听言语处理，伴随着大脑激活的变化，特别是涉及额区。这些变化受听力损失程度的调节。
