The present study investigated the relationship between a volitional life style and activity rest rhythm. High volitional group (HVG : 9Ss, 71.9 years) and low volitional group (LVG : 6Ss, 72.5 years) were identified by the scale of Self-Confidence and Philadelphia Geriatric Center Morale Scale. Actigrams were recorded by a wrist actigraph system for 10 consecutive days with self-reported sleep logs. Sleep periods were distinguished from wakefulness based on wrist activity.
Based on the activity data, circadian rhythm (τ≅, 24hr) and circasemidian rhythm (τ=l2hr) were identified by a least squares spectrum method for both groups. However, the acrophases of these rhythms of LVG were in advance of those of HVG.
The elders of HVG started the naps in the descending period of activity and ended it before the ascending period of activity. On the other hand, the elders of LVG started the naps after the descending trough of activity and ended it during the ascending period of activity. These results suggest that the HVG elders take more efficient naps than the LVG elders.

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During visually imaging, it seems that processing of external stimuli is effected by the visualizing. The present study aims to examine that visualizing diminishes attention allocation to tones, by measuring the amplitude of the event related potentials (ERPs) those are elicited by the tones.
Thirteen students participated. The subjects were instructed to press a button for tones (1000Hz), which were randomly presented with mean ISI of 6 sec, under the three conditions; Visualizing in which they were required to visualize a daily scene, Watching in which they were required to watch a presented picture, Listening in which they were only to attending the tones. ERPs elicited by tones were recorded from Fz, Cz, Pz, Oz, T₅ and T₆. The peak amplitudes of P300 component were analyzed for the 3 conditions.
Reaction time (RT) during the visualizing condition was longer than those of other two conditions. RT during watching picture condition was longer than that of the listening condition. The amplitudes of P300 component were decreased in the visualizing condition than in the other two conditions. These results suggested that during visualizing the allocation of attention to the tone stimuli was more diminished than during watching picture and during attending the tones.

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FMRI (functional magnetic resonance imaging) can measure brain activities in high spatial resolution. We have been investigating the brain areas activated by visuospatial attention using the fMRI. Several visuospatial attention tasks have revealed the significant activities in the parietal and frontal lobe. Our results showed that the superior parietal lobule (SPL) and the intraparietal sulcus (IPS) can be functionally separable, that is, IPS plays a central role in visuospatial attention while SPL is responsible to spatial attention shifts. FEF is shown to be related to voluntary shifts of attention which includes not only spatial one but also attributes such as shapes or colors in visual stimuli.

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