Independence of anticipatory signals for spatial attention from number of nontarget stimuli in the visual field.
Independence of anticipatory signals for spatial attention from number of nontarget stimuli in the visual field.
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空间注意力的预期信号独立于视野中非目标刺激的数量。
DOI：
10.1152/jn.00030.2008
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发表时间：
2008
影响因子：
2.5
通讯作者：
Corbetta,M
中科院分区：
文献类型：
--
作者：
Sestieri,C;Sylvester,CM;Jack,AI;d'Avossa,G;Shulman,GL;Corbetta,M
即使在没有视觉刺激的情况下，隐蔽地关注一个位置也会调节视觉区域的活动。这些影响是广泛的，被发现在皮质表示的关注和无人看管的部分的视野。然而，目前尚不清楚预备调制是否取决于受试者对视野中存在额外非目标刺激的预期。在这里，我们要求受试者内源性地将注意力集中在上视野的外围位置，以确定低对比度目标刺激的方向，我们操纵了其他低对比度非目标刺激在视野中的数量和行为相关性。预期（即，刺激前）血氧水平依赖性（BOLD）信号在对侧关注位置处的增加最强，而信号在未关注的镜像相对的同侧位置/区域处的减少最强。重要的是，这些强烈的预期递减与非目标低对比度刺激的存在/不存在无关，也与较弱的目标诱发反应或较差的表现无关。第二，在视野中的其他低对比度刺激的存在下，即使是潜在的目标，并没有修改预期的信号调制无论是在目标或非目标位置。我们的结论是，地形的空间注意力相关的预期BOLD信号调制整个视觉皮层，特别是在无人值守的位置递减，主要是由过程中的线索位置，而不是由数量或行为相关性的远处低对比度非目标刺激在视野中的其他地方。
Covertly attending to a location modulates the activity of visual areas even in the absence of visual stimulation. These effects are widespread, being found in the cortical representations of both attended and unattended portions of the visual field. It is not clear, however, whether preparatory modulations depend on subjects' expectation regarding the presence of additional nontarget stimuli in the visual field. Here, we asked subjects to endogenously direct attention to a peripheral location in the upper visual field, to identify the orientation of a low-contrast target stimulus, and we manipulated the number and behavioral relevance of other low-contrast nontarget stimuli in the visual field. Anticipatory (i.e., prestimulus) blood oxygenation level–dependent (BOLD) signal increments in visual cortex were strongest at the contralateral attended location, whereas signal decrements were strongest at the unattended mirror-opposite ipsilateral location/region of visual cortex. Importantly, these strong anticipatory decrements were not related to the presence/absence of nontarget low-contrast stimuli and did not correlate with either weaker target-evoked responses or worse performance. Second, the presence of other low-contrast stimuli in the visual field, even when potential targets, did not modify the anticipatory signal modulation either at target or nontarget locations. We conclude that the topography of spatial attention–related anticipatory BOLD signal modulation across visual cortex, specifically decrements at unattended locations, is mainly determined by processes at the cued location and not by the number or behavioral relevance of distant low-contrast nontarget stimuli elsewhere in the visual field.