Department of Psychology, University of Nevada, Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV, 89154, USA.
Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 North Charles Street, Barton Hall, Baltimore, MD, 21218, USA.
Neuroimage. 2020 Jan 1;204:116220. doi: 10.1016/j.neuroimage.2019.116220. Epub 2019 Sep 20.
Understanding the neural underpinning of conscious perception remains one of the primary challenges of cognitive neuroscience. Theories based mostly on studies of the visual system differ according to whether the neural activity giving rise to conscious perception occurs in modality-specific sensory cortex or in associative areas, such as the frontal and parietal cortices. Here, we search for modality-specific conscious processing in the auditory cortex using a bistable stream segregation paradigm that presents a constant stimulus without the confounding influence of physical changes to sound properties. ABA_ triplets (i.e., alternating low, A, and high, B, tones, and _ gap) with a 700 ms silent response period after every third triplet were presented repeatedly, and human participants reported nearly equivalent proportions of 1- and 2-stream percepts. The pattern of behavioral responses was consistent with previous studies of visual and auditory bistable perception. The intermittent response paradigm has the benefit of evoking spontaneous perceptual switches that can be attributed to a well-defined stimulus event, enabling precise identification of the timing of perception-related neural events with event-related potentials (ERPs). Significantly more negative ERPs were observed for 2-streams compared to 1-stream, and for switches compared to non-switches during the sustained potential (500-1000 ms post-stimulus onset). Further analyses revealed that the negativity associated with switching was independent of switch direction, suggesting that spontaneous changes in perception have a unique neural signature separate from the observation that 2-stream percepts evoke more negative ERPs than 1-stream. Source analysis of the sustained potential showed activity associated with these differences originating in anterior superior temporal gyrus, indicating involvement of the ventral auditory pathway that is important for processing auditory objects.
理解意识知觉的神经基础仍然是认知神经科学的主要挑战之一。基于视觉系统研究的理论根据引起意识知觉的神经活动是发生在特定感觉皮层还是在关联区域（如额顶叶皮层）而有所不同。在这里，我们使用双稳态流分离范式在听觉皮层中寻找特定感觉的意识处理，该范式呈现恒定的刺激，而没有声音属性物理变化的混杂影响。ABA_三重奏（即交替的低、A 和高、B 音，以及 _ 间隙），每个三重奏后有 700 ms 的静音响应期，重复呈现，人类参与者报告了几乎相等比例的 1- 和 2-流知觉。行为反应模式与之前的视觉和听觉双稳态知觉研究一致。间歇性响应范式具有唤起自发知觉转换的优点，这些转换可以归因于定义明确的刺激事件，从而能够使用事件相关电位 (ERPs) 精确确定与知觉相关的神经事件的时间。与 1-流相比，2-流观察到的 ERPs 明显更负，与转换相比，非转换观察到的 ERPs 更负，在持续电位（刺激后 500-1000 ms）期间。进一步的分析表明，与切换相关的负性与切换方向无关，这表明自发的知觉变化具有独特的神经特征，与 2-流知觉比 1-流引起更负的 ERPs 的观察结果分开。持续电位的源分析显示，与这些差异相关的活动源自前上颞叶，表明参与处理听觉对象的腹侧听觉通路的重要性。
