Hannah Lerner

Introduction Four-repeat tauopathies (4RT) are neurodegenerative disorders associated with abnormal cytoplasmic inclusions of tau protein isoforms with four microtubule-binding domains.1 The two most common clinical presentations of 4RT include the Richardson syndrome variant of progressive supranuclear palsy (PSP-Richardson) and the corticobasal syndrome (CBS). Alzheimer's disease (AD), which is a tauopathy of three- and four-repeat tau, is a common copathology in both disorders.

Discussion This is the first study to demonstrate that SIS of the M100 responses from the auditory cortex is absent in AD patients, while SIS is evident in matched older adult controls. The reduced SIS in AD patients compared with healthy controls supports the hypothesis that internal prediction mechanisms underlying speech motor control are faulty in AD. Below, we discuss why impaired auditory feedback prediction processes would lead to a reduction in SIS.