The role of spatial attention during spatial encoding.

In the present fMRI study, we aimed to assess whether spatial encoding is mediated by spatial attention. During encoding, participants were presented with abstract shapes to the left or right of fixation. During retrieval, old and new shapes were presented at fixation and participants classified each shape as "old-left", "old-right", or "new". Subsequently remembered items were assumed to have been attended during encoding, while subsequently forgotten items were assumed to have been unattended during encoding. Mirroring classic spatial attention contralateral extrastriate effects, contralateral subsequent memory effects were observed in extrastriate cortical regions BA18 and BA19 (e.g., encoding-left-hits>encoding-left-misses activated the right extrastriate cortex). An additional individual-trial modeling procedure revealed that 79.35% and 100% of accurately encoded items in the left hemisphere and the right hemisphere, respectively, reflected spatial processing. These results suggest that spatial encoding is largely, but not completely, mediated by spatial attention.