  Neural representations of visual perception are affected by mental imagery
and attention. Although attention is known to modulate neural representations,
it is unknown how imagery changes neural representations when imagined and
perceived images semantically conflict. We hypothesized that imagining an image
would activate a neural representation during its perception even while
watching a conflicting image. To test this hypothesis, we developed a
closed-loop system to show images inferred from electrocorticograms using a
visual semantic space. The successful control of the feedback images
demonstrated that the semantic vector inferred from electrocorticograms became
closer to the vector of the imagined category, even while watching images from
different categories. Moreover, modulation of the inferred vectors by mental
imagery depended on both the image category and time from the initiation of
imagery. The closed-loop control of the semantic vectors revealed an
asymmetrical interaction between visual perception and imagery.
