We sought to provide direct evidence of the attention
movements during dynamic mental imagery. Observers
extrapolated in imagery the horizontal motion of a target with
the gaze in central fixation. We recorded the steady-statevisual-
evoked potentials (SSVEP) generated by flickering the
left and right sides of the screen at two different frequencies.
We found a consistent SSVEP modulation as a function of the
imagined target position. Concurrent finger pointing, but not
mental training, increased the SSVEP modulation. We
conclude that the electrophysiological signature of covert
visuospatial attention can be used to reveal non-invasively the
continuous spatio-temporal dynamics of mental imagery.
