Damage to the right parietal lobe will most likely cause a pursuit deficit toward which direction?

• A. Left side (Contralateral)
• B. Right side (Ipsilateral)
• C. Upward
• D. Downward

Answer: (B)

Smooth pursuit relies on the dorsal stream to integrate motion signals and direct the eyes to follow a moving target. The right parietal cortex is especially important for attending to and tracking objects in the left (contralateral) hemispace. When this area is damaged, signals for leftward motion fail to drive the pursuit system effectively, so smooth pursuit is impaired for targets moving to the left. Patients may exhibit catch-up saccades and an inability to maintain continuous tracking on that side. Upward or downward pursuit involve other networks, so the deficit is most pronounced for leftward pursuit, with rightward pursuit relatively preserved. Clinically, a right parietal lesion can also produce left-space neglect, which can further reduce attention to leftward motion.