Neuroanatomy of Unilateral Neglect Syndrome

ABSTRACT

Unilateral spatial neglect is caused by a failure of attentional orienting mechanism. Over 90% of spatial neglect patients have right hemisphere injury. The most frequent sites of damage are right dorsal and ventral frontal cortex (Brodmann area 6, 8, 44), right inferior parietal and superior temporal cortex (Brodmann area 39, 40, 41) and subcortical nuclei (thalamus (pulvinar), putamen, caudate nucleus). Functional neuroimaging studies showed that spatial neglect is associated with lesions of dorsal fronto-parietal network which is involved in top-down control of selective attention, and right ventral fronto-parieto-temporal network which is specialized for detection of salient or unexpected stimuli. The ventral network works as a 'circuit breaker' for the dorsal system, directing attention to salient stimuli. Structural or functional disruption of both network cause unilateral spatial neglect.