Kim Sung Soo, Gomez-Ramirez Manuel, Thakur Pramodsingh H, Hsiao Steven S
The Zanvyl Krieger Mind/Brain Institute, The Johns Hopkins University, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD 21218, USA; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.
The Zanvyl Krieger Mind/Brain Institute, The Johns Hopkins University, Baltimore, MD 21218, USA; The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins School of Medicine, Baltimore, MD 21218, USA.
Neuron. 2015 Apr 22;86(2):555-66. doi: 10.1016/j.neuron.2015.03.020. Epub 2015 Apr 9.
The classical view of somatosensory processing holds that proprioceptive and cutaneous inputs are conveyed to cortex through segregated channels, initially synapsing in modality-specific areas 3a (proprioception) and 3b (cutaneous) of primary somatosensory cortex (SI). These areas relay their signals to areas 1 and 2 where multimodal convergence first emerges. However, proprioceptive and cutaneous maps have traditionally been characterized using unreliable stimulation tools. Here, we employed a mechanical stimulator that reliably positioned animals' hands in different postures and presented tactile stimuli with superb precision. Single-unit recordings in SI revealed that most neurons responded to cutaneous and proprioceptive stimuli, including cells in areas 3a and 3b. Multimodal responses were characterized by linear and nonlinear effects that emerged during early (∼20 ms) and latter (> 100 ms) stages of stimulus processing, respectively. These data are incompatible with the modality specificity model in SI, and provide evidence for distinct mechanisms of multimodal processing in the somatosensory system.
体感加工的经典观点认为，本体感觉和皮肤感觉输入通过分离的通道传递到皮层，最初在初级体感皮层（SI）的模式特异性区域3a（本体感觉）和3b（皮肤感觉）进行突触传递。这些区域将它们的信号传递到区域1和2，在那里首次出现多模式汇聚。然而，传统上使用不可靠的刺激工具来表征本体感觉和皮肤感觉图谱。在这里，我们使用了一种机械刺激器，它能够可靠地将动物的手定位在不同姿势，并以极高的精度呈现触觉刺激。SI中的单神经元记录显示，大多数神经元对皮肤感觉和本体感觉刺激都有反应，包括3a和3b区域的细胞。多模式反应的特征分别是在刺激处理的早期（约20毫秒）和后期（>100毫秒）阶段出现的线性和非线性效应。这些数据与SI中的模式特异性模型不相符，并为体感系统中多模式加工的不同机制提供了证据。
