Involvement of primary visual cortex in visual mental imagery: A transcranial magnetic stimulation study

It has been hypothesized that visual mental imagery and visual perception share the same processing systems in the brain. Evidence from ERP and PET studies examining this hypothesis is conflicting. In this study we investigated whether transcranial magnetic stimulation (TMS) over the occipital pole would interfere with visual imagery. Subjects performed a visual letter-imagery task, while TMS was applied to the occipital cortex (2 cm above the inion). An increase in reaction times was observed at a delay of 300 ms or later in the experimental TMS condition, compared to a control TMS condition with the coil at an angle of 90°. These findings provide TMS evidence for primary visual cortex involvement in visual imagery.