Lateralized alpha oscillatory activity in the inferior parietal lobule to the right hemisphere during left-side visual stimulation.

Understanding the neural mechanisms underlying spatial attention is crucial for unraveling the pathogenesis of unilateral spatial neglect (USN). However, the neural link between spatial attention and USN remains unclear. Thus, the neural mechanisms of spatial attention in the left and right hemispheres were compared. Twenty healthy volunteers participated in a hand mental rotation task in which they determined whether images depicted as left or right hands. The hand images were randomly displayed in the upper, lower, left, and right directions, centered on a fixation point. The laterality index for the alpha oscillatory activity was determined to assess the lateralization of neural activity during visual stimulation. Our results revealed a significant shift in alpha oscillatory neural activity in the inferior parietal lobule (IPL) towards the right hemisphere when visual stimulation occurred on the left side. In contrast, no significant oscillatory shift in the alpha band towards the left hemisphere was observed in the IPL when the visual stimulus was presented on the right side. These findings indicate that the spatial attention on the left side depends on oscillatory alpha activity in the right IPL, whereas that on the right side doesn't depend on either hemispheric alpha activity. These results provide valuable insights into the neural mechanisms of hemispatial neglect.