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 s hare the same processing systems in the brain. Evidence from ERP and PET st udies examining this hypothesis is conflicting. In this study we investigat ed whether transcranial magnetic stimulation (TMS) over the occipital pole would interfere with visual imagery. Subjects performed a visual letter-ima gery task, while TMS was applied to the occipital cortex (2 cm above the in ion). An increase in reaction times was observed at a delay of 300 ms or la ter in the experimental TMS condition, compared to a control TMS condition with the coil at an angle of 90 degrees. These findings provide TMS evidenc e for primary visual cortex involvement in visual imagery.