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Hiroshi Nittono

Publications and source records attributed to Hiroshi Nittono.

18 recordsLinked to original sources
PubMed2006

Effect of voluntary attention on auditory processing during REM sleep.

STUDY OBJECTIVES: The study investigates whether there is an effect of voluntary attention to external auditory stimuli during rapid eye movement (REM) sleep in humans by measuring event-related potentials (ERPs). DESIGN: Using a 2-tone auditory-discrimination task, a standard 1000-Hz tone and a deviant 2000-Hz tone were presented to participants when awake and during sleep. In the ATTENTIVE condition, participants were requested to detect the deviant stimuli during their sleep whenever possible. In the PASSIVE sleep condition, participants were only exposed to the tones. ERPs were measured during REM sleep and compared between the 2 conditions. SETTING: All experiments were conducted at the sleep laboratory of Hiroshima University. PARTICIPANTS: Twenty healthy university student volunteers. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: In the tonic period of REM sleep (the period without REM), P200 and P400 were elicited by deviant stimuli, with scalp distributions maximal at central and occipital sites, respectively. The P400 in REM sleep showed larger amplitudes in the ATTENTIVE condition, whereas the P200 amplitude did not differ between the 2 conditions. No effects on ERPs due to attention were observed during stage 2 sleep. CONCLUSIONS: The instruction to pay attention to external stimuli during REM sleep influenced the late positive potentials. Thus electrophysiologic evidence of voluntary attention during REM sleep has been demonstrated.

Adult↗
PubMed2006

Self-awakening, sleep inertia, and P3 amplitude in elderly people.

It is well known that sleepiness is sometimes experienced in the afternoon. A short afternoon nap is thought to be effective in reducing sleepiness. However, sleep inertia occurs even after a short nap, and this could be a major risk factor for injuries from falling by the elderly. In the present study, the effect of self-awakening on sleep inertia after a 20-min. nap was examined. Nine participants (M=74.1 yr., SD=5.0 yr.) took part in the three experimental conditions: the self-awakened nap, the forced-awakened nap, and the control (no-nap) conditon. Analysis showed sleepiness and performance after the nap significantly improved compared with the control condition. P3 amplitude tended to be larger after self-awakening than after forced-awakening. The present study indicates a 20-min. nap reduces afternoon sleepiness, and the application of self-awakening may contribute to higher arousal after a nap taken by this elderly group.

Age Factors↗
PubMed2005

Voluntary stimulus production enhances deviance processing in the brain.

Humans often get information by voluntary action. However, little is known about how stimulus processing is modulated by self-production of stimuli. In the present study, event-related brain potentials were recorded from 16 student volunteers performing an auditory three-stimulus oddball task in two conditions. In the self condition, the stimuli were triggered by participants' voluntary button presses. In the auto condition, the same stimuli were presented automatically by a computer with the same interstimulus intervals as those in the self condition. Perceptually deviant nontarget stimuli elicited a larger P3 and a larger subsequent positivity in the self condition than in the auto condition, whereas low-deviant target stimuli elicited a P3 with equally high amplitude in both conditions. The findings suggest that voluntary stimulus production enhances orienting of attention (reflected in the P3a component) and subsequent memory updating (reflected in the P3b component) for deviant stimuli, but does not affect the response to task-relevant stimuli. Voluntary action may activate the perceptual representation of its most frequent outcomes and this anticipatory activation may make deviant stimuli more salient in the context.

Acoustic Stimulation↗
PubMed2005

Level of interest in video clips modulates event-related potentials to auditory probes.

This study examined whether a participant's level of interest in visual materials could be assessed by event-related potentials to auditory probe stimuli. Twelve young adults performed an auditory target detection task while viewing either interesting or less interesting (neutral) silent video clips. The auditory probe stimuli consisted of target (2000 Hz, p=0.15), standard (1800 Hz, p=0.70), and nontarget deviant (500 Hz, p=0.15) tones. Button press responses to target tones were required. Both target and deviant tones elicited a large P3 wave, the amplitude of which was smaller while participants were viewing interesting video clips than neutral video clips or simple still images (control condition). The amplitude reduction of the P3 to deviant tones was more prominent than that of the P3 to target tones. The difference between the neutral and control conditions was significant only for the deviant P3. The three-tone probe task using perceptually deviant, nontarget stimuli may be a useful objective method to assess how strongly a visual material attracts the viewer's attention.

Acoustic Stimulation↗
PubMed2005

Examination of the first-night effect during the sleep-onset period.

STUDY OBJECTIVES: The present study examined the first-night effect during the sleep-onset period using the 9 electroencephalogram stage scoring system. DESIGN: After a week of monitoring sleep-wake habits with sleep diaries and wrist actigraphy, polysomnography recording was made for 3 consecutive nights. SETTING: Participants slept in their own private, individual, temperature-controlled bedroom in a sleep laboratory at the university. PARTICIPANTS: Eleven healthy student volunteers (5 women and 6 men, 21 to 25 years old, mean 22.7 years) who had no experience sleeping in a laboratory participated in the study. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The electroencephalogram during the sleep-onset period was scored manually for every 5-second epoch into 9 electroencephalogram stages. Latencies of the electroencephalogram stages were delayed on the first night, especially during the alpha-wave intermittent stages. The average time of the alpha-wave train, intermittent (> 50%) and the electroencephalogram flattening stage increased on Night 1. Stage changes among these stages also increased on Night 1. In contrast, stage changes between the alpha-wave intermittent stage (< 50%) and the theta-wave stage increased on Night 3. CONCLUSIONS: Alpha-wave activity increased on Night 1, demonstrating that the activity of the wake-promoting system during the sleep-onset period was enhanced on the first night. From the second to the third night, the alpha-wave intermittent stage jumped to the theta-wave stage, omitting electroencephalogram flattening, suggesting that the electroencephalogram flattening stage is unlikely to appear during stable sleep-onset period. This is the first study to demonstrate the detail of the first-night effect during the sleep-onset period.

Adult↗
PubMed2005

Brain potentials before and after rapid eye movements: an electrophysiological approach to dreaming in REM sleep.

STUDY OBJECTIVE: This study examined hypotheses regarding dreaming in rapid eye movement (REM) sleep by comparing brain potentials related to rapid eye movements in REM sleep with those in wakefulness. DESIGN: Within participants. SETTING: Data were collected in a sleep laboratory. PARTICIPANTS: Fifteen healthy university students who reported having dreams frequently. MEASUREMENTS AND RESULTS: Rapid eye movements in REM sleep were recorded during natural nocturnal sleep. Saccades in wakefulness were recorded during a self-paced visual search task. The presaccadic negativity before and the lambda response after eye movements were examined. It was assumed that the presaccadic negativity reflects voluntary readiness activity before eye movements, and the lambda response reflects visual information processing after saccades in wakefulness. Brain potentials were averaged, time-locked to the onset and offset of eye movements for the presaccadic negativity and the lambda response, respectively. In wakefulness, the presaccadic negativity occurred at the centroparietal site. However, no presaccadic negativity was found during REM sleep. Lambda-like responses (P1r, P2r) were observed in REM sleep over the parietooccipital site, as were the lambda responses (P1, P2) in wakefulness. CONCLUSIONS: The finding that rapid eye movements are initiated without preparation but elicit some neural activity in the cortical visual area suggests that rapid eye movements may trigger dream images.

Adult↗
PubMed2004

Lack of presaccadic positivity before rapid eye movements in human REM sleep.

Differences between oculomotor control of rapid eye movements (REMs) in REM sleep and that of saccades in wakefulness were examined electrophysiologically in human adults. Fourteen healthy young volunteers participated in the study. Brain potentials were recorded from the scalp and time-locked to the onsets of saccades and REMs during a visually triggered saccade task and natural nocturnal sleep. In wakefulness, presaccadic positivity (PSP) appeared at centro-parietal sites starting about 150 ms before saccades. In REM sleep, no PSP was found but a slow negative potential (pre-REM negativity: PRN) appeared at the prefrontal sites. The findings suggest that the generation of REMs does not involve the cortical process reflected in the PSP but is associated with a different neural process reflected in the PRN.

Adult↗
PubMed2004

Cancel and rethink in the Wason selection task: further evidence for the heuristic-analytic dual process theory.

The reasoning process in the Wason selection task was examined by measuring card inspection times in the letter-number and drinking-age problems. 24 students were asked to solve the problems presented on a computer screen. Only the card touched with a mouse pointer was visible, and the total exposure time of each card was measured. Participants were allowed to cancel their previous selections at any time. Although rethinking was encouraged, the cards once selected were rarely cancelled (10% of the total selections). Moreover, most of the cancelled cards were reselected (89% of the total cancellations). Consistent with previous findings, inspection times were longer for selected cards than for nonselected cards. These results suggest that card selections are determined largely by initial heuristic processes and rarely reversed by subsequent analytic processes. The present study gives further support for the heuristic-analytic dual process theory.

Adult↗
PubMed2004

Subjectively optimal delay in computer response to a user's voluntary action.

It is typically assumed that the shorter the delay in a computer response to a user's action is, the better. In a study examining this assumption, 16 university students were asked to judge the timing of occurrence of either an auditory or a visual stimulus following a voluntary mouse button-press with various durations of delay from 0 to 400 msec. Both a category scaling and an adjustment method of assessment were used to specify the optimal delay with which the user felt most comfortable. When the delay was 50 msec. or shorter, both auditory and visual responses were judged as too fast to be a consequence of the action. The responses were judged as too slow when the delay was 200 msec. or longer for auditory and 300 msec. or longer for visual stimuli. Analysis for the adjustment method indicated that the optimal delay was within 100 to 200 msec. and was longer for visual than for auditory responses. The present study suggests that immediate responses from a computer are not always comfortable and that the insertion of a moderate delay interval may increase the user's sense of control.

Adult↗
PubMed2003

The effects of self-awakening on heart rate activity in a short afternoon nap.

OBJECTIVES: This study examined whether anticipatory changes exist in heart rate prior to awakening from a nap by means of self-awakening. The effects of self-awakening on sleepiness after the short nap were also studied. METHOD: Nine students participated in 3 experimental conditions: (1) the control condition, in which participants watched television instead of taking a short nap; (2) the self-awakening condition, in which participants tried to wake up approximately 15 min after 'lights off' (criterion range: 15+/-5 min) and (3) the forced-awakening condition, in which participants were instructed to sleep for 30 min, but were awoken by the experimenter after 15 min. RESULTS: In the self-awakening condition, heart rate gradually increased approximately 3 min before awakening. The error response ratio of the auditory-oddball task and the duration of doze time during the task were less after both types of nap conditions than in the control condition. Subjective sleepiness, which is measured after awakening, was lowest in the self-awakening condition. CONCLUSIONS: The results of this experiment suggest that self-awakening prepares autonomic activation that facilitates a more smooth transition from sleep to awakening, and reduces sleepiness after naps.

Adult↗
PubMed2003

Effects of self-awakening on sleep structure of a daytime short nap and on subsequent arousal levels.

To investigate the effects of self-awakening on sleep structure and daytime arousal after a short nap, a within-subjects comparison was made of participants in self-awakening and forced-awakening conditions. In the self-awakening condition. participants were instructed to wake up by themselves 15 min. after the experimenter turned the lights off. In the forced-awakening condition, the experimenter awakened them 20 min. after the lights were turned off. To control the maximum sleep time for the two conditions, we used different instructions in each condition. Participants were 10 healthy college students. Their physiological arousal and subjective sleepiness were evaluated using the P300 amplitude of the auditory event-related potential (ERP) and the visual analog scale previously described by Monk and Kathryn, et al. For evaluating sleep structure during the nap, Hori's 1994 hypnagogic EEG stages were used. P300 amplitude was significantly lower, and subjective sleepiness was significantly higher after forced-awakening than self-awakening, indicating that arousal was higher after self-awakening. The EEGs during napping in the forced-awakening condition indicated deeper sleep. Given this deeper sleep, severe sleep inertia occurred after the forced-awakening condition. In conclusion, it appeared a short nap with self-awakening was more effective in reducing a post-lunch dip than one with forced-awakening.

Adult↗
PubMed2002

Word imageability and N400 in an incidental memory paradigm.

High imagery words are memorized better than low imagery words. To examine how these words are processed at encoding, event-related potentials (ERPs) were recorded in an incidental memory paradigm. Frequency-matched high and low imagery words (45 words each) were presented in a random order on a computer screen. Twelve university students were asked to rate the imageability of a word's referent on a five-point scale. High imagery words elicited a larger N400 than low imagery words did. The N400 was more left-lateralized for low imagery words than for high imagery words, suggesting that some neural generators (probably in the right hemisphere) were not involved in the processing of low imagery words. Difference waveforms showed that the N400 was followed by a second negativity (N800), which was also larger for high imagery words and had a scalp distribution similar to that of the N400. Subsequent free recall showed a classical imagery effect that high imagery words were recalled better than low imagery words. These results suggest that the superiority of high imagery words over low imagery words in incidental memory results from more extensive activation of a semantic network distributed across the left and right hemispheres, the latter of which probably deals with imagery-related information that is not activated by low imagery words.

Adult↗
PubMed2002

Comparison of the event-related potentials between tonic and phasic periods of rapid eye movement sleep.

The event-related potentials (ERP) of eight young healthy volunteers were recorded during wakefulness and rapid eye movement (REM) sleep using an auditory discrimination task. REM sleep was classified into phasic and tonic periods according to the presence or absence of REM. In wakefulness, deviant stimuli elicited a P300 that was maximal over parieto-central areas. During the tonic period of REM sleep, deviant stimuli elicited a P200 and a P400. The P200 was distributed more anteriorly and the P400 was distributed more posteriorly than the P300; however, no prominent ERP components were observed during the phasic period. The study's findings suggest that the brain is less sensitive to external stimuli during the phasic period than during the tonic period of REM sleep.

Adult↗
PubMed2002

Brain potentials associated with the onset and offset of rapid eye movement (REM) during REM sleep.

The relationship between dreaming and rapid eye movements (REM) during REM sleep is still controversial. This study records the brain potentials time-locked to the onset and offset of REM in 11 healthy young volunteers. Before the onset of REM, no presaccadic readiness potential was found. Conversely, two positive potentials (P1 and P2) appeared following the offset of REM. The latter potentials were dominant in the parieto-occipital area. These findings suggest that REM is initiated without preparation but elicits some information-processing activities that were speculated to occur in the cortical visual area. The data support the activation-synthesis or association hypothesis of dreaming rather than the scanning hypothesis.

Adult↗
PubMed2002

Nocturnal heart rate and volitional lifestyle in the elderly.

The relationship between the level of volitional lifestyle and nocturnal heart rate (HR) in the elderly was investigated. Twenty high- and low-volitional elderly individuals (n = 10 each; mean age 73.2 years) participated in the study. Heart rate during nocturnal sleep was recorded at their homes using an ambulatory polysomnographic system. High-volitional individuals showed a lower HR throughout the night and less variability during rapid eye movement sleep. These findings suggest that a volitional lifestyle of the elderly has a beneficial effect on autonomic activity during sleep.

Aged↗
PubMed2002

Volitional lifestyle in healthy elderly: its relevance to rest-activity cycle, nocturnal sleep, and daytime napping.

Sleep-related problems are prevalent among the aged. The present study examined the influence of a mentally active or "volitional" lifestyle on the rest-activity cycle, nocturnal sleep, and daytime napping in the healthy elderly. 14 aged individuals with a high Volitional lifestyle (M = 74.1 yr. old) and 14 with a Low Volitional lifestyle (M = 73.0 yr. old) were screened by questionnaires including the Philadelphia Geriatric Center Morale scale and the Self-confidence scale. Their activity levels were monitored by a wrist actigraph system for 14 consecutive days. They were also asked to record daily sleep logs. The total times of nocturnal sleep and daytime napping did not differ between the groups. However, the acrophases of circadian (tau = 24 hr.) and circasemidian (tau = 12 hr.) activity cycles were more advanced in the Low Volitional group. In addition, the High Volitional group took a daytime nap with a better timing than did the Low Volitional group: the former started a nap during the phase in which their activity level was going down, whereas the latter when their activity level was going up. These results suggest that high volitional lifestyle may be related to better rest-activity cycle in the healthy elderly.

Aged↗
PubMedDate not supplied

Brain potentials after clicking a mouse: a new psychophysiological approach to human-computer interaction.

As a first step in developing a new psychophysiological technique to assess mental workload in human-computer interaction (HCI), we recorded event-related brain potentials for visual stimuli triggered by voluntary mouse clicks. Twelve university students clicked a mouse button at their own pace. Each click triggered 1 of 3 alphabetic letters assigned to frequent standard, rare target, and rare nontarget stimuli. Counting target stimuli was required. Both rare stimuli elicited a P3 (P300) wave, the amplitude of which was larger when the stimuli were triggered by mouse clicks than when the same stimuli were presented automatically without mouse clicks. Postmotor potentials associated with clicking were small in amplitude (<2 microV) and did not temporally overlap with the P3. The findings suggest that the P3 can be recorded for a computer's response to the user's intentional action and may be used as a measure of perceptual-central processing resources allocated to the HCI task. Actual or potential applications of this research include the evaluation of the user's attentional state during HCI byrecording brain potentials in the "mouse click" or action-perception paradigm.

Adult↗