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Mismatch negativity in aging and in Alzheimer's and Parkinson's diseases
1Department of Neurology, Helsinki University Central Hospital, Finland. eero@biomag.helsinki.fi
Abstract:
Mismatch negativity (MMN) is an auditory event-related potential (ERP) that reflects automatic stimulus discrimination in the human auditory system. By varying the interstimulus intervals (ISIs), the MMN can be used as an index of auditory sensory memory. This paper focuses on MMN findings in aging and in Alzheimer's (AD) and Parkinson's diseases (PD). The accumulated data suggest that MMN to duration deviance, unlike MMN to frequency deviance, is reduced in amplitude in aging at short ISIs. The attenuated MMN to frequency deviance observed at long ISIs in elderly subjects seems to be caused by age-related memory trace decay. Existing results suggest that automatic discrimination for the frequency change is not affected in the early phase of AD, whereas the memory trace seems to decay faster in AD patients. The present findings on PD are not as conclusive, although they tentatively suggest deteriorated automatic change detection. The MMN appears to offer an objective tool for studying auditory processing and memory trace decay in different neurological disorders.
Insights
Mismatch negativity (MMN), an auditory evoked potential, shows reduced amplitude in aging and neurological disorders like Alzheimer's and Parkinson's. MMN reflects auditory sensory memory and automatic stimulus discrimination.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Cognitive Neuroscience
Background:
- Mismatch negativity (MMN) is an auditory event-related potential (ERP) indexing automatic auditory discrimination.
- MMN variations with interstimulus intervals (ISIs) serve as a measure of auditory sensory memory.
- Aging and neurodegenerative diseases like Alzheimer's (AD) and Parkinson's (PD) impact auditory processing.
Purpose of the Study:
- To investigate MMN alterations in aging, AD, and PD.
- To examine the role of ISIs in MMN changes related to aging and disease.
- To assess MMN as a potential biomarker for auditory processing deficits.
Main Methods:
- Auditory event-related potentials (ERPs) were recorded.
- Mismatch negativity (MMN) was elicited using duration and frequency deviant stimuli.
- Interstimulus intervals (ISIs) were manipulated to probe sensory memory.
Main Results:
- Aging showed reduced MMN amplitude to duration deviance at short ISIs.
- Age-related memory trace decay was implicated in MMN attenuation to frequency deviance at long ISIs.
- Early AD did not affect automatic frequency change detection, but accelerated memory trace decay; PD findings were inconclusive.
Conclusions:
- MMN is sensitive to age-related changes in auditory processing and memory.
- MMN alterations may indicate faster memory decay in Alzheimer's disease.
- MMN shows promise as an objective measure for auditory processing and memory deficits in neurological disorders.