Sanada Motoyuki, Shimada Morihiro, Katayama Jun'ichi
Department of Psychological Science, Kwansei Gakuin University, 1-155 Uegahara Ichiban-cho, Nishinomiya-shi, Hyogo, 662-8501, Japan.
Center for Applied Psychological Science (CAPS), Kwansei Gakuin University, Nishinomiya-shi, Japan.
Exp Brain Res. 2025 Jun 4;243(7):166. doi: 10.1007/s00221-025-07114-8.
In a three-stimulus oddball task, the P3a event-related potential (ERP) is typically elicited by an infrequent deviant, with its amplitude increasing under difficult task conditions. In the visual modality, this P3a enhancement has been shown to reflect attentional process rather than response inhibition to the deviant. This study aimed to examine whether P3a amplitude increase by task difficulty in the auditory modality also reflects attentional process. The same experimental design as in the visual study was applied, manipulating stimulus category (three- vs. two-category) and task difficulty (easy vs. difficult). In the three-category condition, stimuli included standard tones, target deviant tones, and non-target deviant chords, with only target deviant tones requiring a response. In the two-category condition, stimuli were categorized into standard tones, target deviant tones and target deviant chords. Thus, the difference between the two conditions is that deviant chords were non-target or target. Task difficulty was varied by adjusting frequency distance between standard tones and target deviant tones. If P3a reflects attentional process, enhancement should occur in both conditions, while response inhibition would only enhance P3a in the three-category condition. Results showed that P3a amplitude increased by task difficulty occurred in both conditions, supporting the attentional process hypothesis. The fact that the P3a augmentation reflects attentional process regardless of sensory modality suggests that this process is mediated by modality-independent neural mechanisms.
在三刺激偏差任务中，P3a事件相关电位（ERP）通常由罕见的偏差刺激诱发，其波幅在困难任务条件下会增大。在视觉模态中，这种P3a增强已被证明反映的是注意过程而非对偏差刺激的反应抑制。本研究旨在检验在听觉模态中，任务难度导致的P3a波幅增加是否也反映注意过程。采用了与视觉研究相同的实验设计，操纵刺激类别（三类与两类）和任务难度（简单与困难）。在三类条件下，刺激包括标准音、目标偏差音和非目标偏差和弦，只有目标偏差音需要做出反应。在两类条件下，刺激被分为标准音、目标偏差音和目标偏差和弦。因此，两种条件之间的差异在于偏差和弦是非目标的还是目标的。通过调整标准音和目标偏差音之间的频率距离来改变任务难度。如果P3a反映注意过程，那么在两种条件下都应出现增强，而反应抑制只会在三类条件下增强P3a。结果表明，两种条件下均出现了任务难度导致的P3a波幅增加，支持了注意过程假说。P3a增强反映注意过程这一事实与感觉模态无关，表明该过程由模态独立的神经机制介导。
