Department of Vision Science, UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
J Neurophysiol. 2010 Dec;104(6):3644-56. doi: 10.1152/jn.00303.2010. Epub 2010 Sep 15.
Spatial attention modulates signal processing within visual nuclei of the thalamus--but do other nuclei govern the locus of attention in top-down mode? We examined functional MRI (fMRI) data from three subjects performing a task requiring covert attention to 1 of 16 positions in a circular array. Target position was cued after stimulus offset, requiring subjects to perform target detection from iconic visual memory. We found positionally specific responses at multiple thalamic sites, with individual voxels activating at more than one direction of attentional shift. Voxel clusters at anatomically equivalent sites across subjects revealed a broad range of directional tuning at each site, with little sign of contralateral bias. By reference to a thalamic atlas, we identified the nuclear correspondence of the four most reliably activated sites across subjects: mediodorsal/central-intralaminar (oculomotor thalamus), caudal intralaminar/parafascicular, suprageniculate/limitans, and medial pulvinar/lateral posterior. Hence, the cortical network generating a top-down control signal for relocating attention acts in concert with a spatially selective thalamic apparatus-the set of active nuclei mirroring the thalamic territory of cortical "eye-field" areas, thus supporting theories which propose the visuomotor origins of covert attentional selection.
空间注意调节丘脑视觉核团内的信号处理——但其他核团是否以自上而下的模式控制注意的焦点？我们检查了三个受试者执行一项任务的 fMRI 数据，该任务要求受试者在一个圆形排列中 covert 注意 16 个位置中的 1 个。目标位置在刺激结束后提示，要求受试者从图标视觉记忆中进行目标检测。我们在多个丘脑部位发现了位置特异性反应，单个体素在多个注意力转移方向上激活。在受试者之间的解剖学上等效部位的体素簇显示了每个部位的广泛的方向性调谐，几乎没有对侧偏向的迹象。通过参考丘脑图谱，我们确定了四个最可靠地在受试者中激活的部位的核对应关系：mediodorsal/central-intralaminar（动眼神经核）、caudal intralaminar/parafascicular、suprageniculate/limitans 和 medial pulvinar/lateral posterior。因此，生成用于重新定位注意力的自上而下控制信号的皮质网络与空间选择性丘脑仪器协同作用——活跃核的集合反映了皮质“眼区”的丘脑区域，从而支持了提出隐蔽注意力选择的运动起源的理论。
