Task-related activations in heterotopic brain malformations: a PET study.

POSITRON emission tomography (PET) studies have shown normal or elevated levels of glucose metabolism in neuronal heterotopia, raising the issue of potential participation of heterotopic neurons in cognitive processing. We studied three patients with heterotopic malformations, using [ 15 O]water PET and experimental conditions selected according to the location of the malformations. Task performance was associated with blood flow increases of > 17% within the heterotopia in each patient. In two, these occurred in left frontal heterotopia during sentence generation. In the third patient, activations for facial and visuospatial discrimination and picture naming were found in a right posterior heterotopion. Our findings may reflect participation of heterotopia in cognitive function and suggest that heterotopic neurons synapse with neurons in other brain regions.