Martínez A, Di Russo F, Anllo-Vento L, Sereno M I, Buxton R B, Hillyard S A
Department of Radiology, University of California, San Diego, La Jolla, CA 92093-8756, USA.
Vision Res. 2001;41(10-11):1437-57. doi: 10.1016/s0042-6989(00)00267-4.
This study investigated the cortical mechanisms of visual-spatial attention in a task where subjects discriminated patterned targets in one visual field at a time. Functional magnetic imaging (fMRI) was used to localize attention-related changes in neural activity within specific retinotopic visual areas, while recordings of event-related brain potentials (ERPs) traced the time course of these changes. The earliest ERP components enhanced by attention occurred in the time range 70-130 ms post-stimulus onset, and their neural generators were estimated to lie in the dorsal and ventral extrastriate visual cortex. The anatomical areas activated by attention corresponded closely to those showing increased neural activity during passive visual stimulation. Enhanced neural activity was also observed in the primary visual cortex (area V1) with fMRI, but ERP recordings indicated that the initial sensory response at 50-90 ms that was localized to V1 was not modulated by attention. Modeling of ERP sources over an extended time range showed that attended stimuli elicited a long-latency (160-260 ms) negativity that was attributed to the dipolar source in area V1. This finding is in line with hypotheses that V1 activity may be modulated by delayed, reentrant feedback from higher visual areas.
本研究在一项任务中探究了视觉空间注意的皮层机制，该任务要求受试者每次辨别一个视野中的图案目标。功能磁共振成像（fMRI）用于定位特定视网膜拓扑视觉区域内与注意相关的神经活动变化，而事件相关脑电位（ERP）记录则追踪这些变化的时间进程。受注意增强的最早ERP成分出现在刺激开始后70 - 130毫秒的时间范围内，其神经发生器估计位于背侧和腹侧纹外视觉皮层。受注意激活的解剖区域与被动视觉刺激期间显示神经活动增加的区域密切对应。fMRI还观察到初级视觉皮层（V1区）神经活动增强，但ERP记录表明，在50 - 90毫秒时定位于V1区的初始感觉反应不受注意调节。在更长时间范围内对ERP源进行建模显示，受注意刺激引发了一种长潜伏期（160 - 260毫秒）负波，该负波归因于V1区的偶极源。这一发现与以下假设一致，即V1区的活动可能受到来自更高视觉区域的延迟、折返反馈的调节。
