Can simple delayed response tasks affect latency and amplitude of magnetoencephalographic midline alpha rhythms (612 Hz) in early dementia?We recruited 15 mild Alzheimers disease (AD) and 10 vascular dementia (VaD) patients (paired mini mental state exam of 1724). The control groups comprised 18 young and 22 elderly normal subjects. In the first task, a simple cue stimulus (one bit) was memorized along a brief delay period (3.55.5 s) up to a go stimulus triggering (right or left) button press. In the second task, the cue stimulus remained available along the delay period. Event-related reduction in power of the alpha rhythms indexed the cortical activation (event-related desynchronization, ERD) for the trials associated with correct behavioral responses. Behavioral performances to both tasks were lower in the AD and VaD patients than in the normal subjects. In particular, just four AD and five VaD patients executed a sufficient amount of correct responses for the alpha ERD analysis, so they were included in a unique group. In both tasks, the alpha ERD peak was later in latency in the demented and normal elderly subjects than in the normal young subjects. Furthermore, the alpha ERD peak was stronger in amplitude in the demented patients than in the normal subjects. These results suggest that simple delayed response tasks during physiological recordings are quite difficult for patients even at an early dementia stage. Such difficulty may induce the abnormal amount of the related cortical activation in dementia as revealed by the alpha ERD
Alpha rhythms in mild dements during visual delayed choice reaction time tasks. A MEG study
Tecchio F;Zappasodi F;
2005
Abstract
Can simple delayed response tasks affect latency and amplitude of magnetoencephalographic midline alpha rhythms (612 Hz) in early dementia?We recruited 15 mild Alzheimers disease (AD) and 10 vascular dementia (VaD) patients (paired mini mental state exam of 1724). The control groups comprised 18 young and 22 elderly normal subjects. In the first task, a simple cue stimulus (one bit) was memorized along a brief delay period (3.55.5 s) up to a go stimulus triggering (right or left) button press. In the second task, the cue stimulus remained available along the delay period. Event-related reduction in power of the alpha rhythms indexed the cortical activation (event-related desynchronization, ERD) for the trials associated with correct behavioral responses. Behavioral performances to both tasks were lower in the AD and VaD patients than in the normal subjects. In particular, just four AD and five VaD patients executed a sufficient amount of correct responses for the alpha ERD analysis, so they were included in a unique group. In both tasks, the alpha ERD peak was later in latency in the demented and normal elderly subjects than in the normal young subjects. Furthermore, the alpha ERD peak was stronger in amplitude in the demented patients than in the normal subjects. These results suggest that simple delayed response tasks during physiological recordings are quite difficult for patients even at an early dementia stage. Such difficulty may induce the abnormal amount of the related cortical activation in dementia as revealed by the alpha ERDI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
