Cortical activity time locked to the shift and maintenance of spatial attention

Akiko Ikkai, Clayton E. Curtis

Research output: Contribution to journalArticlepeer-review


Attention increases the gain of visual neurons, which improves visual performance. How attention is controlled, however, remains unknown. Clear correlations between attention and saccade planning indicate that the control of attention is mediated through mechanisms housed in the oculomotor network. Here, we used event-related functional magnetic resonance imaging to compare overt and covert attention shifts. Subjects covertly or overtly shifted attention based on an endogenous cue and maintained attention throughout a long and variable delay. To insure continued attention, subjects counted when the attended target dimmed at near-threshold contrast levels. Overt and covert tasks used identical stimuli and required identical motor responses. Additionally, a staircase procedure that adjusted the target-dimming contrast separately for covert and overt trials equated the difficulty between conditions and across subjects. We found that the same regions along the precentral and intraparietal sulci were active during shifts of covert and overt attention. We also found sustained activation in the hemisphere contralateral to the attended visual field. We conclude that maps of prioritized locations are represented in areas classically associated with oculomotor control. The readout of these spatial maps by posterior visual areas directs spatial attention just as the readout by downstream saccade generators directs saccades.

Original languageEnglish (US)
Pages (from-to)1384-1394
Number of pages11
JournalCerebral Cortex
Issue number6
StatePublished - Jun 2008


  • Attention
  • Control
  • Eye field
  • Saccade
  • Salience
  • Spatial
  • fMRI

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience


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