Fu Shimin, Zinni Marla, Squire Peter N, Kumar Reshma, Caggiano Daniel M, Parasuraman Raja
ARCH Laboratory, MS 3F5, George Mason University, Fairfax, VA 22030-4444, USA.
Neuroimage. 2008 Feb 1;39(3):1345-55. doi: 10.1016/j.neuroimage.2007.09.068. Epub 2007 Oct 13.
Perceptual load is recognized to affect visual selective attention, but at an unknown spatiotemporal locus in the brain. To examine this issue, event-related potentials (ERPs) were recorded while participants performed an orientation discrimination task, under conditions of low or high perceptual load. Participants were required to respond to targets (10% of trials) presented in the attended visual field while ignoring all stimuli in the unattended visual field. The interaction between voluntary attention and perceptual load was significant for the posterior N1 component (190 ms) but not for the earlier C1 (84 ms) or P1 (100 ms) components. This load by attention interaction for N1 was localized to the temporoparietal-occipital (TPO) gyrus by dipole modeling analysis. Dipole modeling also showed that a reversed attentional effect in the C1 time range was due to ERP overlap from the subsequent attention-sensitive P1 component. Results suggest that perceptual load affects voluntary visuospatial attention at an early (but not the earliest) processing stage and that the TPO gyrus mediates target selection at the discrimination stage.
知觉负载被认为会影响视觉选择性注意，但在大脑中其时空位置尚不清楚。为了研究这个问题，在参与者执行方向辨别任务时，记录了事件相关电位（ERP），实验设置了低或高知觉负载条件。要求参与者对出现在被关注视野中的目标（占试验次数的10%）做出反应，同时忽略未被关注视野中的所有刺激。自愿注意和知觉负载之间的相互作用对后部N1成分（190毫秒）有显著影响，但对较早的C1（84毫秒）或P1（100毫秒）成分没有显著影响。通过偶极子模型分析，N1的这种负载与注意的相互作用定位于颞顶枕（TPO）回。偶极子模型还表明，C1时间范围内注意效应的反转是由于后续对注意敏感的P1成分的ERP重叠所致。结果表明，知觉负载在早期（但不是最早）加工阶段影响自愿视觉空间注意，并且TPO回在辨别阶段介导目标选择。
