Spatial awareness is a function of the temporal not the posterior parietallobe

Our current understanding of spatial behaviour and parietal lobe function i s largely based on the belief that spatial neglect in humans (a lack of awa reness of space on the side of the body contralateral to a brain injury) is typically associated with lesions of the posterior parietal lobe. However, in monkeys, this disorder is observed after lesions of the superior tempor al cortex(1), a puzzling discrepancy between the species. Here we show that , contrary to the widely accepted view, the superior temporal cortex is the neural substrate of spatial neglect in humans, as it is in monkeys. Unlike the monkey brain, spatial awareness in humans is a function largely confin ed to the right superior temporal cortex, a location topographically remini scent of that for language on the left(2). Hence, the decisive phylogenetic transition from monkey to human brain seems to be a restriction of a forme rly bilateral function to the right side, rather than a shift from the temp oral to the parietal lobe. One may speculate that this lateralization of sp atial awareness parallels the emergence of an elaborate representation for language on the left side.