Effects of temporal-parietal lesions on the somatosensory P3 to lower limb stimulation.

Temporal-parietal junction lesions reduce the auditory and upper limb somatosensory P3 event-related potential (ERP) to target and novel stimuli. The current study examined the somatosensory P3 to target and novel stimuli delivered to the sole of the foot in patients with unilateral temporal-parietal lesions (n = 6). Age-matched controls (n = 10) generated a parietal maximal target P3 and a frontal-central maximal novelty P3 ERP to foot stimulation. Unilateral temporal-parietal lesions abolished target and novelty P3 responses over all scalp sites for stimuli delivered contralateral to the lesion. The P3 was also reduced to ipsilateral stimuli at electrodes over the lesioned hemisphere with partial P3 preservation observed at electrode sites over the non-lesioned hemisphere. These results parallel the findings for upper limb stimulation and support the critical role of temporal-parietal cortex in P3 generation.