NeuroSyntax Lab, Department of Communication Sciences and Disorders, Arnold School of Public Health, University of South Carolina, 915 Greene Street, Columbia, SC, 29208, USA.
Speech Neuroscience Lab, Department of Speech, Language, and Hearing, Callier Center for Communication Disorders, School of Behavioral and Brain Sciences, The University of Texas at Dallas, 2811 N. Floyd Rd, Richardson, TX, 75080, USA.
Exp Brain Res. 2024 Jan;242(1):225-239. doi: 10.1007/s00221-023-06743-1. Epub 2023 Nov 24.
The present study examined opposing and following vocal responses to altered auditory feedback (AAF) to determine how damage to left-hemisphere brain networks impairs the internal forward model and feedback mechanisms in post-stroke aphasia. Forty-nine subjects with aphasia and sixty age-matched controls performed speech vowel production tasks while their auditory feedback was altered using randomized ± 100 cents upward and downward pitch-shift stimuli. Data analysis revealed that when vocal responses were averaged across all trials (i.e., opposing and following), the overall magnitude of vocal compensation was significantly reduced in the aphasia group compared with controls. In addition, when vocal responses were analyzed separately for opposing and following trials, subjects in the aphasia group showed a significantly lower percentage of opposing and higher percentage of following vocal response trials compared with controls, particularly for the upward pitch-shift stimuli. However, there was no significant difference in the magnitude of opposing and following vocal responses between the two groups. These findings further support previous evidence on the impairment of vocal sensorimotor control in aphasia and provide new insights into the distinctive impact of left-hemisphere stroke on the internal forward model and feedback mechanisms. In this context, we propose that the lower percentage of opposing responses in aphasia may be accounted for by deficits in feedback-dependent mechanisms of audio-vocal integration and motor control. In addition, the higher percentage of following responses may reflect aberrantly increased reliance of the speech system on the internal forward model for generating sensory predictions during vocal error detection and motor control.
本研究通过改变听觉反馈（AAF）来观察对立和跟随的发声反应，以确定左半球脑网络损伤如何损害卒中后失语症的内部前馈模型和反馈机制。49 名失语症患者和 60 名年龄匹配的对照组在进行语音元音产生任务时，其听觉反馈会受到随机 ± 100 音分的向上和向下音高移位刺激的影响。数据分析显示，当将所有试验（即对立和跟随）的发声反应平均化时，与对照组相比，失语症组的发声补偿总体幅度明显降低。此外，当对立和跟随试验的发声反应分别进行分析时，与对照组相比，失语症组的对立和跟随发声反应试验的比例明显降低，尤其是对于向上的音高移位刺激。然而，两组之间对立和跟随发声反应的幅度没有显著差异。这些发现进一步支持了以前关于失语症发声运动控制受损的证据，并为左半球卒中对内前馈模型和反馈机制的独特影响提供了新的见解。在这种情况下，我们提出失语症中对立反应的比例较低可能是由于音频-声音整合和运动控制的反馈依赖机制缺陷所致。此外，跟随反应的比例较高可能反映了语音系统在检测发声错误和进行运动控制时对内部前馈模型的异常依赖增加。
