Auditory discrimination after left-hemisphere stroke: a mismatch negativity follow-up study

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Clinical Neurophysiology

Background:

• Left-hemisphere stroke can lead to aphasia and impaired auditory discrimination.
• Assessing auditory processing recovery is crucial for understanding stroke rehabilitation.

Purpose of the Study:

• To evaluate the recovery of cortical auditory discrimination in aphasic stroke patients.
• To utilize mismatch negativity (MMN) and speech-comprehension tests as measures of recovery.

Main Methods:

• Mismatch negativity (MMN) was recorded in 8 left-hemisphere stroke patients at multiple time points post-stroke (4 days, 10 days, 3 months, 6 months).
• MMN responses to duration and frequency changes were analyzed.
• Speech-comprehension tests (Boston Diagnostic Aphasia Examination) were administered.
• Eight age-matched healthy individuals served as controls.

Main Results:

• Initially, patients showed impaired sound discrimination, indicated by reduced MMN amplitudes, particularly for right-ear stimuli.
• Significant recovery of MMN to duration changes was observed by 3 months post-stroke.
• Auditory discrimination showed progressive improvement in speech-comprehension tests throughout the follow-up period.
• A correlation was found between MMN amplitude changes and speech-comprehension test scores.

Conclusions:

• Mismatch negativity (MMN) serves as a reliable electrophysiological index for assessing the recovery of auditory discrimination after stroke.
• These findings highlight the potential of MMN in monitoring neuroplasticity and auditory rehabilitation in stroke survivors.