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Several neuropsychological studies have suggested parallel processing of somatosensory input when localising a tactile stimulus on one's own by pointing towards it (body schema) and when localising this touched location by pointing to it on a map of a hand (body image). Usually these reports describe patients with impaired detection, but intact sensorimotor localisation. This study examined three patients with a lesion of the angular gyrus with intact somatosensory processing, but with selectively disturbed finger identification (finger agnosia). These patients performed normally when pointing towards the touched finger on their own hand but failed to indicate this finger on a drawing of a hand or to name it. Similar defects in the perception of other body parts were not observed. The findings provide converging evidence for the dissociation between body image and body schema and, more importantly, reveal for the first time that this distinction is also present in higher-order cognitive processes selectively for the fingers.

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.