A Cortical Substrate for Square-Wave Jerks in Progressive Supranuclear Palsy.

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Square-wave jerks (SWJs) are common in progressive supranuclear palsy (PSP).
• The exact cause of SWJs in PSP remains unclear.
• Investigating SWJs helps understand PSP pathophysiology.

Purpose of the Study:

• Characterize SWJs in PSP (Richardson subtype) and Parkinson's disease (PD).
• Identify brain structures associated with abnormal SWJ parameters in PSP.
• Differentiate SWJ generation mechanisms between PSP and PD.

Main Methods:

• Recorded eye movements in 12 PSP patients, 12 PD patients, and 12 controls using infrared oculography.
• Analyzed SWJ rate, amplitude, and velocity.
• Performed voxel-based morphometry on MRI scans to correlate brain volume with SWJ parameters.

Main Results:

• PSP patients exhibited a threefold higher SWJ rate compared to PD patients and controls.
• Midbrain or infratentorial atrophy did not correlate with SWJ rate.
• Significant association found between high SWJ rate and atrophy in temporal lobe gyri (superior, middle, inferior) in PSP patients.

Conclusions:

• Midbrain atrophy does not mediate SWJs in PSP.
• Supratentorial cortical structures, particularly in the temporal lobe, are implicated in generating high SWJ rates in PSP.
• Temporal lobe connections to the superior colliculus and cerebellum may influence SWJ genesis.