Woldorff M G, Liotti M, Seabolt M, Busse L, Lancaster J L, Fox P T
Center for Cognitive Neuroscience, Duke University, Box 90999, Durham, NC 27708-0999, USA.
Brain Res Cogn Brain Res. 2002 Dec;15(1):1-15. doi: 10.1016/s0926-6410(02)00212-4.
The temporal dynamics of the effects of lateralized visual selective attention within the lower visual field were studied with the combined application of event-related potentials (ERPs) and positron emission tomography (15O PET). Bilateral stimuli were rapidly presented to the lower visual field while subjects either passively viewed them or covertly attended to a designated side to detect occasional targets. Lateralized attention resulted in strongly enhanced PET activity in contralateral dorsal occipital cortex, while ERPs showed an enhanced positivity (P1 effect, 80-160 ms) for all stimuli (both non-targets and targets) over contralateral occipital scalp. Dipole modeling seeded by the dorsal occipital PET foci yielded an excellent fit for the peak P1 attention effect. However, more detailed ERP modeling throughout the P1 latency window (90-160 ms) suggested a spatial-temporal movement of the attention-related enhancement that roughly paralleled the shape of the dorsal occipital PET attention-related activations-likely reflecting the sequential attention-related enhancement of early visual cortical areas. Lateralized spatial attention also resulted in a longer-latency contralateral enhanced negativity (N2 effect, 230-280 ms) with a highly similar distribution to the earlier P1 effect. Dipole modeling seeded by the same dorsal occipital PET foci also yielded an excellent fit. This pattern of results provides evidence for re-entrance of attention-enhanced activation to the same retinotopically organized region of dorsal extrastriate cortex. Finally, target stimuli in the attended location elicited an additional prolonged enhancement of the longer-latency negativity over contralateral occipital cortex. The combination of PET activation and dipole modeling suggested contribution from a ventral-occipital generator to this target-related activity.
采用事件相关电位（ERP）和正电子发射断层扫描（15O PET）相结合的方法，研究了下视野内单侧视觉选择性注意效应的时间动态变化。向受试者的下视野快速呈现双侧刺激，受试者要么被动观看，要么 covertly 关注指定一侧以检测偶尔出现的目标。单侧注意导致对侧枕叶背侧皮质的PET活动显著增强，而ERP显示，对侧枕部头皮上所有刺激（包括非目标刺激和目标刺激）的正性增强（P1效应，80 - 160毫秒）。由枕叶背侧PET焦点作为种子点进行偶极子建模，对P1注意效应的峰值拟合效果极佳。然而，在整个P1潜伏期窗口（90 - 160毫秒）进行更详细的ERP建模表明，与注意相关的增强存在时空移动，大致与枕叶背侧PET注意相关激活的形状平行，这可能反映了早期视觉皮层区域与注意相关的顺序增强。单侧空间注意还导致潜伏期更长的对侧负性增强（N2效应，230 - 280毫秒），其分布与早期的P1效应高度相似。由相同的枕叶背侧PET焦点作为种子点进行偶极子建模，拟合效果也极佳。这种结果模式为注意增强的激活重新进入背侧纹外皮层的同一视网膜拓扑组织区域提供了证据。最后，在被关注位置的目标刺激在对侧枕叶皮质上引发了潜伏期更长的负性增强的额外延长。PET激活和偶极子建模的结合表明，腹侧枕叶发生器对这种与目标相关的活动有贡献。
