Abstract
Based on the pulvinar’s widespread connectivity with the visual cortex, as well as with putative attentional source regions in the frontal and parietal lobes, the pulvinar is suspected to play an important role in visual attention. However, there remain many hypotheses on the pulvinar’s specific function. One hypothesis is that the pulvinar may play a role in filtering distracting stimuli when they are actively ignored. Because it remains unclear whether this is the case, how this might happen, or what the fate of the ignored objects is, we sought to characterize the spatial representation of visual information in the human pulvinar for equally salient attended and ignored objects that were presented simultaneously. In an fMRI experiment, we measured the spatial precision with which attended and ignored stimuli were encoded in the pulvinar, and we found that attention completely gated position information: attended objects were encoded with high spatial precision, but there was no measurable spatial encoding of actively ignored objects. This is despite the fact that the attended and ignored objects were identical and present simultaneously, and both attended and ignored objects were represented with great precision throughout the visual cortex. These data support a role for the pulvinar in distractor filtering and reveal a possible mechanism: by modulating the spatial precision of stimulus encoding, signals from competing stimuli can be suppressed in order to isolate behaviorally relevant objects.
Meeting abstract presented at VSS 2012