Inadequate inhibition of redundant auditory inputs in Alzheimer's disease: An MEG study

This study aimed to characterize the cortical deficits in processing auditory inputs in patients with Alzheimer's disease (AD). The magnetic counterparts of P50 (M50) and mismatch negativity (MMNm) during a passive oddball paradigm were analyzed with equivalent current dipole modeling. The results showed larger cortical activation of standard-evoked M50 in AD patients compared to young and elderly controls. In contrast, smaller amplitudes and longer peak latencies were found in the MMNm of the elderly and AD patients compared with young adults. The MMNm latency was longer in AD patients than in elderly controls. A Spearman correlation test showed an inverse correlation between the cortical strengths of M50 and MMNm in the right hemisphere. In conclusion, age-related changes in the M50 and MMNm components, which may reflect deficits in central auditory processing, are discussed, along with the possibility that increased M50 responses are related to decreased inhibition of redundant inputs in mild AD.

► Inadequate inhibition of redundant auditory input in Alzheimer's disease.
► Larger M50 response in Alzheimer's disease.
► Auditory inhibition deficits in Alzheimer's disease.
► M50 amplitude correlated inversely with MMNm.