Neural correlates of hemispatial neglect: A voxel-based SPECT study

Background: Despite many studies that investigated the neural correlates of hemispatial neglect (HN) with structural imaging, studies using voxel-wise analyses of functional imaging are not available. Furthermore, previous studies neither considered the neglect severity nor investigated whether there are differences in these neural correlates according to each neglect subtest. This study aimed to investigate the neural correlates of HN by correlating the total and the individual neglect score with hypoperfusion value on single photon emission computed tomography (SPECT) using voxel-wise analyses. Methods: Forty-two patients with acute right hemisphere strokes underwent a neglect test battery consisting of 3 bisection tasks, 2 cancellation tasks and 2 copying tasks. The SPECT images were acquired in these patients and 10 age- and education-matched normal controls. Results: Patients with HN, compared to those without HN, had hypoperfusion in the right middle temporal-occipital junction, inferior frontal gyrus and retrosplenial area. The total neglect score correlated with the hypoperfusion in the right middle temporal-occipital junction, fusiform gyrus, parahippocampal gyrus, inferior temporal gyrus, anterior part of the superior and middle temporal gyri, cuneus, lingual gyrus, angular gyrus, and the cerebellum. Across the neglect subtests similar correlation patterns were observed with minor variations. Conclusions: Unlike the results of previous studies showing that the critical neural correlates for HN are inferior parietal lobule or superior temporal gyrus, our study showed that the lesions that critically contribute to the neglect severity were located in the posterior parts of the middle temporal gyrus (temporal-occipital junction).