Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA.
The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA.
Neuroimage. 2017 Mar 1;148:318-329. doi: 10.1016/j.neuroimage.2016.12.074. Epub 2017 Jan 11.
Non-invasive neuroimaging studies have shown that semantic category and attribute information are encoded in neural population activity. Electrocorticography (ECoG) offers several advantages over non-invasive approaches, but the degree to which semantic attribute information is encoded in ECoG responses is not known. We recorded ECoG while patients named objects from 12 semantic categories and then trained high-dimensional encoding models to map semantic attributes to spectral-temporal features of the task-related neural responses. Using these semantic attribute encoding models, untrained objects were decoded with accuracies comparable to whole-brain functional Magnetic Resonance Imaging (fMRI), and we observed that high-gamma activity (70-110Hz) at basal occipitotemporal electrodes was associated with specific semantic dimensions (manmade-animate, canonically large-small, and places-tools). Individual patient results were in close agreement with reports from other imaging modalities on the time course and functional organization of semantic processing along the ventral visual pathway during object recognition. The semantic attribute encoding model approach is critical for decoding objects absent from a training set, as well as for studying complex semantic encodings without artificially restricting stimuli to a small number of semantic categories.
非侵入性神经影像学研究表明，语义类别和属性信息是在神经群体活动中编码的。脑电描记术（ECoG）相对于非侵入性方法具有几个优势，但在 ECoG 反应中编码语义属性信息的程度尚不清楚。我们记录了患者从 12 个语义类别中命名物体时的 ECoG，并随后训练了高维编码模型，将语义属性映射到任务相关神经反应的光谱-时间特征上。使用这些语义属性编码模型，未受过训练的物体的解码准确率与全脑功能磁共振成像（fMRI）相当，我们观察到基底枕颞电极的高伽马活动（70-110Hz）与特定的语义维度（人造-有生命的、常规大-小的、地方-工具）相关。个体患者的结果与其他成像模式的报告密切一致，这些报告涉及在物体识别过程中腹侧视觉通路中语义处理的时间进程和功能组织。语义属性编码模型方法对于解码不在训练集中的物体以及研究复杂的语义编码非常重要，而无需将刺激人为地限制在少数语义类别中。
