Department of Psychiatry and Psychotherapy, University of Regensburg, Universitätsstraße 84, 93053, Regensburg, Germany.
Brain Struct Funct. 2018 Dec;223(9):4087-4098. doi: 10.1007/s00429-018-1740-z. Epub 2018 Aug 24.
Perceptual decision making is the cognitive process wherein the brain classifies stimuli into abstract categories for more efficient downstream processing. A system that, during categorization, can process information regardless of the information's original sensory modality (i.e., a supramodal system) would have a substantial advantage over a system with dedicated processes for specific sensory modalities. While many studies have probed decision processes through the lens of one sensory modality, it remains unclear whether there are such supramodal brain areas that can flexibly process task-relevant information regardless of the original "format" of the information. To investigate supramodality, one must ensure that supramodal information exists somewhere within the functional architecture by rendering information from multiple sensory systems necessary but insufficient for categorization. To this aim, we tasked participants with categorizing auditory and tactile frequency-modulated sweeps according to learned, supramodal categories in a delayed match-to-category paradigm while we measured their blood-oxygen-level dependent signal with functional MRI. To detect supramodal information, we implemented a set of cross-modality pattern classification analyses, which demonstrated that the left caudate nucleus encodes category-level information but not stimulus-specific information (such as spatial directions and stimulus modalities), while the right inferior frontal gyrus, showing the opposite pattern, encodes stimulus-specific information but not category-level information. Given our paradigm, these results reveal abstract representations in the brain that are independent of motor, semantic, and sensory-specific processing, instead reflecting supramodal, categorical information, which points to the caudate nucleus as a locus of cognitive processes involved in complex behavior.
知觉决策是大脑将刺激分类为抽象类别以进行更有效的下游处理的认知过程。在分类过程中，能够处理信息而不受信息原始感觉模态限制的系统（即超模态系统）将比具有特定感觉模态专用过程的系统具有显著优势。虽然许多研究已经通过一种感觉模态的视角探究了决策过程，但仍然不清楚是否存在这样的超模态大脑区域，能够灵活地处理与任务相关的信息，而不受信息原始“格式”的限制。为了研究超模态，必须通过使来自多个感觉系统的信息对于分类是必要但不充分的，来确保在功能架构中存在超模态信息。为此，我们要求参与者在延迟匹配到类别范式中根据学习的超模态类别对听觉和触觉调频扫频进行分类，同时我们使用功能磁共振成像测量他们的血氧水平依赖性信号。为了检测超模态信息，我们实施了一系列跨模态模式分类分析，这些分析表明，左侧尾状核编码类别水平的信息而不编码刺激特异性信息（如空间方向和刺激模态），而右侧下额叶，表现出相反的模式，编码刺激特异性信息而不编码类别水平信息。鉴于我们的范式，这些结果揭示了大脑中的抽象表示，这些表示独立于运动、语义和感觉特异性处理，而是反映了超模态、分类信息，这指向尾状核作为涉及复杂行为的认知过程的所在地。
