Effects of mental rotation on acalculia: Differences in the direction of mental rotation account for the differing characteristics of acalculia induced by right and left hemispheric brain injury

Abstract

We observed a 59-year-old right-handed man with an infarction in his right-middle cerebral artery that included the parietal lobe, who abnormally manipulated mental images in the horizontal direction, resulting in calculation disturbances. Three years later, the patient suffered an infarction in the left parietal lobe and displayed abnormalities during the creation of mental images; i.e., he rotated them in the vertical direction, which again resulted in calculation disturbances. These mental imagery disturbances might indicate that a common acalculia mechanism exists between the right and left hemispheres.

Keywords:

• Acalculia
• Brain damage
• Hemispheric differences
• Mental rotation disturbance

We are grateful to Professor K. Takeda for helpful suggestions regarding acalculia at the first evaluation.

Conflict of Interest: The authors have no conflicts of interest.