Abstract
Current models of cognitive control have argued that the frontal cortex dynamically allocates attentional resources during perceptual decisions. Specifically, momentary changes in sensory or response interference may result in top-down modulations of sensory input. To test this hypothesis, we performed fMRI using a visual motion interference task in which two sets of black and white moving dots were simultaneously presented. Human subjects made simple decisions about the direction of motion of the target dots while ignoring the distractor dots. In this task, reaction time increased with the amount of sensory interference whereas error rate increased with the amount of response interference. These behavioral differences allowed us to psychophysically dissociate these two types of interference. We found neural activity modulated by the amount of sensory interference only in sensory cortex (area MT+/V5), whereas activity modulated by the amount of response interference was located only in frontal cortex (supplementary motor cortex). Furthermore, functional connectivity between sensory and frontal cortex during the decision was found to be close to zero. These data suggest that interference is minimized and resolved locally without engaging top-down feedback loops.
Meeting abstract presented at VSS 2014