Donders Institute for Brain, Cognition, and Behavior, Radboud University Nijmegen, Netherlands.
J Cogn Neurosci. 2012 Mar;24(3):677-85. doi: 10.1162/jocn_a_00164. Epub 2011 Nov 8.
Effective processing of sensory input in daily life requires attentional selection and amplification of relevant input and, just as importantly, attenuation of irrelevant information. It has been proposed that top-down modulation of oscillatory alpha band activity (8-14 Hz) serves to allocate resources to various regions, depending on task demands. In previous work, we showed that contralateral somatosensory alpha activity decreases to facilitate processing of an anticipated target stimulus in a tactile discrimination task. In the current study, we asked whether somatosensory alpha activity is also modulated when expecting incoming distracting stimuli on the nonattended side. We hypothesized that an ipsilateral increase of alpha to suppress distracters would be required for optimal task performance. We recorded magneto-encephalography while subjects performed a tactile stimulus discrimination task where a cue directed attention either to their left or right hand. Distracters were presented simultaneously to the unattended hand. We found that alpha power contralateral to the attended hand decreased, whereas ipsilateral alpha power increased. In addition, posterior alpha power showed a general increase. Importantly, these three alpha components all contributed to discrimination performance. This study further extends the notion that alpha band activity is involved in shaping the functional architecture of the working brain by determining the engagement and disengagement of specific regions: Contralateral alpha decreases to facilitate stimulus detection, whereas ipsilateral alpha increases when active suppression of distracters is required. Importantly, the ipsilateral alpha increase is crucial for optimal task performance.
日常生活中有效处理感觉输入需要注意力选择和放大相关输入，同样重要的是，衰减不相关信息。有人提出，自上而下的调制振荡 alpha 波段活动（8-14 Hz）可根据任务需求分配资源到各个区域。在以前的工作中，我们表明，对侧体感 alpha 活动的减少有助于在触觉辨别任务中处理预期的目标刺激。在当前的研究中，我们想知道当期待非关注侧传入的分心刺激时，体感 alpha 活动是否也会被调节。我们假设，为了获得最佳的任务表现，需要同侧的 alpha 增加来抑制分心物。当受试者执行触觉刺激辨别任务时，我们记录了脑磁图，其中提示将注意力引导到左手或右手。分心物同时呈现给未被关注的手。我们发现，与被关注手相对应的 alpha 功率降低，而同侧的 alpha 功率增加。此外，后 alpha 功率普遍增加。重要的是，这三个 alpha 成分都有助于辨别性能。这项研究进一步扩展了这样一种观点，即 alpha 波段活动通过确定特定区域的参与和脱离来参与塑造工作大脑的功能结构：对侧 alpha 减少以促进刺激检测，而当需要主动抑制分心物时，同侧 alpha 增加。重要的是，同侧 alpha 的增加对于最佳的任务表现至关重要。
