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

Music Instruments That Produce Sounds with Inaudible High-Frequency Components <Research Material>

Many kinds of audio-visual information from daily life have been digitized. Digitization accuracy is important to perceptions or evaluations of audio naturalness, and to listener comfort during the listening experience. High-resolution digital sound sources with inaudible high-frequency components (>20 kHz) have become available, owing to recent advances in information and communications technology. However, the effects of sounds that feature such components on human psychophysiological processes have not been sufficiently discussed. One of the reasons for this dearth of research could be that it remains unclear what musical instruments produce sounds with such components. In this technical note, we introduce some percussion instruments that produce sounds with inaudible high-frequency components, and present sound spectra and spectrograms of those sounds. High-frequency components in excess of 20 kHz appeared, in abundance, in the rising phase—but not in the falling phase—of a sound wave. In a sound wave of a tambourine, high-frequency components appeared not only in the rising phase but also in the falling phase. The tambourine sound could be a feasible study subject, given how it features abundant inaudible high-frequency components; it could be used to examine the effects of sounds that feature them on human psychophysiological processes.本稿は，JSPS科研費(15J06118)の助成を受けた研究の一環である

The Use of Event-Related Potentials in Psychological Research

Event-related potentials (ERPs) are voltage fluctuations of the brain that are time-locked to some physical or mental occurrence. These potentials can be recorded safely from the human scalp and provide valuable information about the brain activity associated with perception, cognition, and behavior. This paper deals with theoretical issues concerning the use of ERPs in psychological research. Following a brief description of the basic method of ERP recording, technical problems that can occur in the recording and analysis of the ERP were discussed (e.g., ocular artifacts, averaging, and individual differences). Then, the problems of isolating and interpreting ERP components were addressed. Finally, the relationship between the ERP and other psychological measures was discussed in the light of functional systems of the brain. It was concluded that the ERP can serve as a valuable tool in psychological research only if it is combined with other psychological measures

Event-related potentials elicited by unexpected visual stimuli after voluntary actions

Event-related potentials from visual stimuli that were presented after voluntary actions were recorded to examine how people expect their action effects. Participants pressed a button in response to a cue stimulus (L or R) either in the fixed condition where participants always pressed a center button or in the choice condition where they selectively pressed the corresponding left or right button. Immediately after the button press, a second stimulus (left or right) was presented visually to inform that their action was registered. When the second stimulus did not match the cue stimulus (p = .20), a late positive potential (LPP) with a posterior scalp distribution occurred in a latency range of 500-700 ms. The amplitude of this mismatch-related LPP was larger in the choice condition than in the fixed condition. The results suggest that the cognitive mismatch between the expected and actual action effects is reflected in the LPP, and the selection of a specific action strengthens the expectation of its action effect

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

Generator sources of 14Hz/12Hz sleep spindles during stage 2 sleep

The present study investigated the equivalent dipole sources of two types of human sleep spindles (14 and 12Hz) during stage 2 sleep. Dipole analysis of the 21 scalp EEGs (Fp1,Fp2,F3,F4,C3,C4,P3,P4,O1,O2,F7,F8,T3,T4,T5,T6,Fpz, Fz, Cz, Pz and Oz) was carried out on ten male subjects (20-26yr). This study showed that sleep spindle can be represented by single equivalent dipole. For both 14 and 12Hz sleep spindles, the equivalent dipole sources appeared in center of the brain. The orientation of the equivalent dipole of 14Hz sleep spindle was in the centro-parietal direction, while that of 12Hz sleep spindle was in the frontal direction. These results suggest that both types of sleep spindle activities are generated in the thalamus, and the thalamo-cortical pathway are different for the two types of sleep spindles

Effects of self-awakening on sleep structure and sleep inertia during or after the short nap

本研究の目的は, 短時期仮眠における自己覚醒の企図が, 睡眠構造および睡眠慣性に及ぼす影響を検討することである。実験は, 自分で目覚める自己覚醒条件と,実験者が強制的に覚醒させる強制覚醒条件の参加者内比較計画で行った。覚醒水準の評価には, 聴覚オドボール課題により算出された事象関連電位のP300と課題正反応時間,Visual Analog Scale (Vas)による主観的覚醒水準評定値を用いた。睡民構造の詳細な検討のために,Hori et al. (1994)の脳波段階判定(9段階)を用いた。実験参加者は,大学生・大学院生14名であった。実験参加者は,4minの聴覚オドボール課題と1minのVAS評定からなる計5分間の課題を2セッション(計10分間)行った。その後,約20分間の仮眠をとり,覚醒後に同様の課題を6セッション(計30分間)行った。本研究の結果,自己覚醒を用いて出眠した場合には,強制覚醒の場合と比べて,P300振幅は大きくなり,主観的眠気は低減していた。また,自己覚醒を意図した場合には,睡眠構造が浅くなる傾向があった。これらの結果から,強制覚醒よりも自己覚醒をもちいた仮眠が,午後の眠気を抑える方法として有効であることが示された。(518語)The aim of this study was the investigation of the effects of self-awakening on sleep inertia and sleep structure at the short nap. The participants were take part in the self-awakening and forced-awakening condition. In the self-awakening condition, participant woke up by themselves. However, experimenter in the forced-awakening condition waked participants up. The physiological arousal level and subjective sleepiness were evaluated by P300 of the event related potential (ERP) and visual analog scale (VAS). For evaluating the sleep structure elaborately, we used the Hori's EEG stages. Participants were 14 healthy college students. They participated the task consist of auditory oddball task (4 min) and VAS rating (1 min). Participant carried out two sessions (10 min) before the nap. Thereafter, they took a short nap around 20 min. After the nap, they carried out six sessions (30 min) again. P300 amplitude was lower after forced -awakening than self-awakening. On the other hand, subjective sleepiness was greater after the forced-awakening than self-awakening. And sleep structure was deeper during the forced-awakening than self-awakening. Those results suggest that a short nap with self-awakening was more useful than with forced-awakening