TY - JOUR

T1 - Spatially distributed encoding of covert attentional shifts in human thalamus

AU - Hulme, Oliver J

AU - Whiteley, Louise Emma

AU - Shipp, Stewart

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

KW - Adult

KW - Attention

KW - Brain Mapping

KW - Female

KW - Humans

KW - Image Processing, Computer-Assisted

KW - Magnetic Resonance Imaging

KW - Male

KW - Photic Stimulation

KW - Space Perception

KW - Thalamic Nuclei

KW - Young Adult

U2 - 10.1152/jn.00303.2010

DO - 10.1152/jn.00303.2010

M3 - Journal article

C2 - 20844113

VL - 104

SP - 3644

EP - 3656

JO - Journal of Neurology & Neurophysiology

JF - Journal of Neurology & Neurophysiology

SN - 2155-9562

IS - 6

ER -