Neuroscience & Mental Health Program, The Hospital for Sick Children, 555 University Avenue, Room 4265, Toronto, Ontario, Canada M5G 1X8.
Neuroimage. 2010 Jan 15;49(2):1777-85. doi: 10.1016/j.neuroimage.2009.09.035. Epub 2009 Sep 23.
Recent studies have shown evidence of somatosensory deficits in individuals with attentional difficulties yet relatively little is known about the role of attention in the processing of somatosensory input. Neuromagnetic imaging studies have shown that rhythmic oscillations within the human somatosensory cortex are strongly modulated by somatosensory stimulation and may reflect the normal processing of such stimuli. However, few studies have examined how attention influences these cortical oscillations. We examined attentional effects on human somatosensory oscillations during median nerve stimulation by conducting time-frequency analyses of neuromagnetic recordings in healthy adults. We found that selective attention modulated somatosensory oscillations in the alpha, beta, and gamma bands that were both phase-locked and non-phase-locked to the stimulus. In the primary somatosensory cortex (SI), directing the subject's attention toward the somatosensory stimulus resulted in increased gamma band power (30-55 Hz) that was phase-locked to stimulus onset. Directed attention also produced an initial suppression (desynchrony) followed by enhancement (synchrony) of beta band power (13-25 Hz) that was not phase-locked to the stimulus. In the secondary somatosensory cortex (SII), directing attention towards the stimulus increased phase-locked alpha (7-9 Hz) power approximately 30 ms after onset of phase-locked gamma in SI, followed by a non-phase-locked increase in alpha power. We suggest that earlier phase-locked oscillatory power may reflect the relay of input from SI to SII, whereas later non-phase-locked rhythms reflect stimulus-induced oscillations that are modulated by selective attention and may thus reflect enhanced processing of the stimulus underlying the perception of somatosensory events.
最近的研究表明，注意力困难的个体存在体感缺陷的证据，但人们对注意力在体感输入处理中的作用知之甚少。神经磁成像研究表明，人类体感皮层内的节律性振荡强烈地受到体感刺激的调制，可能反映了对这种刺激的正常处理。然而，很少有研究探讨注意力如何影响这些皮层振荡。我们通过对健康成年人的神经磁记录进行时频分析，研究了注意对正中神经刺激下人体体感振荡的影响。我们发现，选择性注意调制了与刺激锁相和非锁相的 alpha、beta 和 gamma 频段的体感振荡。在初级体感皮层（SI）中，引导受试者的注意力朝向体感刺激会导致与刺激起始锁相的 gamma 频段功率（30-55 Hz）增加。定向注意还会产生初始抑制（去同步），然后是 beta 频段功率（13-25 Hz）的增强（同步），与刺激不锁相。在次级体感皮层（SII）中，将注意力引导到刺激上会增加与锁相 gamma 在 SI 中起始锁相的 alpha 功率（7-9 Hz），大约 30 毫秒后，随后是非锁相的 alpha 功率增加。我们认为，早期的锁相振荡功率可能反映了从 SI 到 SII 的输入传递，而后期的非锁相节律反映了由选择性注意调制的刺激诱导的振荡，因此可能反映了对感知体感事件的刺激的增强处理。
