Preserved stimulus deviance detection in Alzheimer's disease.
Aging attenuates automatic auditory discrimination to duration change, whereas frequency change detection is relatively unimpaired in aging and in Alzheimer's disease (AD). Here we studied with a whole-head magnetometer whether cortical auditory discrimination to duration change as shown by magnetic mismatch negativity (MMNm) response is impaired in AD. Twenty AD patients with mild to moderate cognitive impairment and 18 age-matched healthy subjects were monaurally presented a sequence of frequent standard tones embedded with occasional deviants with shorter duration. MMNm was significantly delayed in the left hemisphere ipsilaterally to the ear stimulated in the patient group, whereas the MMNm amplitudes over both hemispheres were quite similar in both groups. This suggests that although MMNm is delayed in the left hemisphere, the automatic discrimination to duration change in the auditory cortex is not attenuated in the early stages of AD.
Pekkonen
E
E
Department of Neurology, University of Helsinki, and Medical Engineering Centre, Helsinki University Central Hospital, Finland.
Jääskeläinen
L P
LP
Erkinjuntti
T
T
Hietanen
M
M
Huotilainen
M
M
Ilmoniemi
R J
RJ
Näätänen
R
R
D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000503:physiopathology* / Q000523:psychology*; D001303:Auditory Cortex / Q000503:physiopathology*; D001307:Auditory Perception / Q000502:physiology*; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D004192:Discrimination, Psychological / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D013998:Time Perception / Q000502:physiology*