Effects of head rotation on space- and word-based reading errors in spatial neglect

Area of Science:

• Neuroscience
• Cognitive Psychology
• Ophthalmology

Background:

• Right hemisphere lesions can cause neglect dyslexia (ND), characterized by omissions and word-based reading errors.
• ND involves neglecting text on the left side or initial word letters, with errors categorized as space-based or word-based.
• Egocentric reference frames (head, trunk, eyes) influence spatial attention, but their effect on ND reading errors is unclear.

Purpose of the Study:

• To investigate if egocentric manipulations, specifically head-rotation (HR), influence omission and word-based reading errors in patients with ND.
• To compare the effects of HR on different types of reading errors in right-hemisphere lesioned patients with and without ND, and in healthy controls.

Main Methods:

• A controlled study involving right-hemisphere lesioned patients with and without ND, and matched healthy controls.
• Utilized indented paragraph reading tests to assess reading errors.
• Investigated the impact of passive leftward head-rotation (HR) on omission and word-based reading errors.

Main Results:

• Passive leftward HR significantly reduced omission errors on the left side of the text in patients with ND.
• Head-rotation had no significant effect on word-based reading errors in patients with ND.
• The findings suggest a dissociation between the effects of egocentric manipulation on space-based attention versus word identification.

Conclusions:

• Egocentric manipulations like head-rotation primarily influence space-based attentional processes in neglect, as evidenced by reduced omissions in paragraph reading.
• These manipulations do not impact the attentional processes involved in word identification, which manifest as word-based errors in neglect dyslexia.
• The study highlights the specific role of egocentric reference frames in spatial attention deficits within neglect dyslexia.