题目：Representations of attentional priority in human visual cortex

报告人：John Serences, Associate professor Department of Psychology Neuroscience Graduate Program University of California, San Diego

时间：2014年12月09日 星期二 13:00-14:30

地点： 生命科学学院邓佑才报告厅

邀请人: 方方

摘要:Computational theories propose that spatial attention modulates the topographical landscape of ‘priority’ maps in regions of visual cortex so that the location of an important object is associated with higher activation levels. Consistent with this framework, single-unit recording studies reveal attention-related increases in the gain of neural responses as well as changes in the size of spatial receptive fields. However, the joint impact of these modulations on the overall fidelity of region-level priority maps is not well understood. Here, we used fMRI to reconstruct spatial representations of attended and ignored stimuli using large-scale activation patterns measured from areas of occipital, parietal and frontal cortex. We observed a variety of different modulations in single voxels, including increases and decreases in both response amplitude and receptive field size. However, using information from all voxels to reconstruct spatial representations of attended stimuli reveals that attention selectively increases the amplitude of stimulus representations, without substantively changing their size. In a second study, we used a similar method to examine the role of these priority maps in mediating the precision of spatial working memory (WM). Patterns of activation in multiple occipital and parietal visual areas supported reconstructed representations of remembered – but not forgotten – locations. Moreover, the amplitude of representations of remembered locations decreased with increasing memory load, in line with a corresponding decrease in memory recall performance. Together, these results provide initial insights into how fluctuations in the topography of spatial priority maps can influence the fidelity of both sensory and mnemonic representations.