Department of Optometry and Vision Sciences, The University of Melbourne, Parkville 3010, Australia.
Department of Anatomy & Neuroscience, The University of Melbourne, Parkville 3010, Australia.
Neuroimage. 2014 Jun;93 Pt 1:47-52. doi: 10.1016/j.neuroimage.2014.02.023. Epub 2014 Feb 28.
Heavy demands are placed on the brain's attentional capacity when selecting a target item in a cluttered visual scene, or when reading. It is widely accepted that such attentional selection is mediated by top-down signals from higher cortical areas to early visual areas such as the primary visual cortex (V1). Further, it has also been reported that there is considerable variation in the surface area of V1. This variation may impact on either the number or specificity of attentional feedback signals and, thereby, the efficiency of attentional mechanisms. In this study, we investigated whether individual differences between humans performing attention-demanding tasks can be related to the functional area of V1. We found that those with a larger representation in V1 of the central 12° of the visual field as measured using BOLD signals from fMRI were able to perform a serial search task at a faster rate. In line with recent suggestions of the vital role of visuo-spatial attention in reading, the speed of reading showed a strong positive correlation with the speed of visual search, although it showed little correlation with the size of V1. The results support the idea that the functional size of the primary visual cortex is an important determinant of the efficiency of selective spatial attention for simple tasks, and that the attentional processing required for complex tasks like reading are to a large extent determined by other brain areas and inter-areal connections.
当在杂乱的视觉场景中选择目标项目或阅读时，大脑的注意力容量会受到很大的压力。人们普遍认为，这种注意力选择是由来自更高皮质区域的自上而下的信号介导的，这些信号传递到初级视觉皮层（V1）等早期视觉区域。此外，据报道，V1 的表面积存在相当大的差异。这种变化可能会影响注意力反馈信号的数量或特异性，从而影响注意力机制的效率。在这项研究中，我们调查了执行注意力任务的人类之间的个体差异是否与 V1 的功能区域有关。我们发现，那些在 fMRI 的 BOLD 信号测量中 V1 对中央 12°视野的代表性更大的人，能够以更快的速度执行串行搜索任务。与最近关于视空间注意力在阅读中的重要作用的观点一致，阅读速度与视觉搜索速度呈很强的正相关，尽管与 V1 的大小相关性很小。结果支持这样一种观点，即初级视觉皮层的功能大小是决定简单任务中选择性空间注意力效率的重要决定因素，而像阅读这样的复杂任务所需的注意力处理在很大程度上由其他大脑区域和区域间连接决定。
