Reduced automatic frontal response to auditory deviance in Huntington's disease as indexed by magnetic mismatch negativity.

Huntington's disease (HD) is a neurodegenerative disorder accompanied by a degradation of dopaminergic receptors. It is evident that dopaminergic dysfunction leads to attention deterioration. However, little is known about the functional integrity of involuntary attention processing in patients with HD. The present study aimed to investigate whether patients with HD exhibit a deficit in automatic deviance detection that can be indexed by magnetic mismatch responses. Magnetoencephalographic responses during a passive oddball task were recorded to examine automatic neural activation to auditory deviants in patients with symptomatic HD and age and sex-matched healthy volunteers. The mean amplitude and peak latency of magnetic mismatch responses were calculated from the waveforms in each hemisphere. Furthermore, minimum current estimate (MCE) was applied to estimate the source strength of temporal and frontal mismatch responses. Compared with healthy participants, patients with HD exhibited a decreased waveform amplitude and a prolonged peak latency of magnetic mismatch responses in the left temporal lobe. The MCE analysis also revealed significantly lower activation of the bilateral frontal mismatch responses in patients. In conclusion, the frontal underactivation to occasional auditory deviance suggests a deficit of involuntary attention switching in HD.