Kida Tetsuo, Inui Koji, Wasaka Toshiaki, Akatsuka Kosuke, Tanaka Emi, Kakigi Ryusuke
Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Aichi, Japan.
J Neurophysiol. 2007 May;97(5):3585-96. doi: 10.1152/jn.00007.2007. Epub 2007 Mar 14.
The neural mechanisms underlying unimodal spatial attention have long been studied, but the cortical processes underlying cross-modal links remain a matter of debate. To reveal the cortical processes underlying the cross-modal links between vision and touch in spatial attention, we recorded magnetoencephalographic (MEG) responses to electrocutaneous stimuli when subjects directed attention to an electrocutaneous or visual stimulus presented randomly in the left or right space. Neural responses recorded around the bilateral sylvian fissures at 85 and 100 ms after the electrocutaneous stimulus were significantly enhanced by spatial attention in both the touch-irrelevant and -relevant modalities. Source analysis revealed that the sylvian responses were generated in the secondary somatosensory cortex (SII). An early response, M50c, generated in the contralateral primary somatosensory cortex (SI), was not modulated by attention. There were no significant attentional changes in the source location or magnetic field distribution, suggesting attentional facilitation of the neural activity in SII itself, rather than a tonic bias effect or overlapping of separate neuronal populations. The results show that spatial attention enhances responses to tactile inputs in SII, independent of sensory modality attended. The underlying mechanism remains to be determined, but may be an increase in gain.
单峰空间注意力的神经机制早已得到研究，但跨模态联系背后的皮层过程仍存在争议。为了揭示空间注意力中视觉与触觉之间跨模态联系背后的皮层过程，我们记录了受试者将注意力导向随机出现在左或右空间的电皮肤刺激或视觉刺激时，对电皮肤刺激的脑磁图（MEG）反应。在电皮肤刺激后85和100毫秒，双侧颞叶沟周围记录到的神经反应在与触觉无关和相关的模态中均因空间注意力而显著增强。源分析表明，颞叶沟反应是在次级体感皮层（SII）产生的。在对侧初级体感皮层（SI）产生的早期反应M50c不受注意力调节。源位置或磁场分布没有显著的注意力变化，这表明是对SII自身神经活动的注意力促进作用，而不是紧张性偏倚效应或单独神经元群体的重叠。结果表明，空间注意力增强了SII中对触觉输入的反应，与所关注的感觉模态无关。其潜在机制仍有待确定，但可能是增益增加。
