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NOGUCHI YasukiGraduate School of Humanities / Division of Human Social DynamicsProfessor
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■ Paper- UNLABELLED: The integration of auditory and visual stimuli is essential for effective language processing and social perception. The present study aimed to elucidate the mechanisms underlying audio-visual (A-V) integration by investigating the temporal dynamics of multisensory regions in the human brain. Specifically, we evaluated inter-trial coherence (ITC), a neural index indicative of phase resetting, through scalp electroencephalography (EEG) while participants performed a temporal-order judgment task that involved auditory (beep, A) and visual (flash, V) stimuli. The results indicated that ITC phase resetting was greater for bimodal (A + V) stimuli compared to unimodal (A or V) stimuli in the posterior temporal region, which resembled the responses of A-V multisensory neurons reported in animal studies. Furthermore, the ITC got lager as the stimulus-onset asynchrony (SOA) between beep and flash approached 0 ms. This enhancement in ITC was most clearly seen in the beta band (13-30 Hz). Overall, these findings highlight the importance of beta rhythm activity in the posterior temporal cortex for the detection of synchronous audiovisual stimuli, as assessed through temporal order judgment tasks. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11571-024-10183-0.Jan. 2025, Cognitive Neurodynamics, 19(1) (1), 28 - 28, English, International magazine[Refereed]Scientific journal
- When we memorize multiple words simultaneously, semantic relatedness among those words assists memory. For example, the information about "apple", "banana," and "orange" will be connected via a common concept of "fruits" and become easy to retain and recall. Neural mechanisms underlying this semantic integration in verbal working memory remain unclear. Here I used electroencephalography (EEG) and investigated neural signals when healthy human participants memorized five nouns semantically related (Sem trial) or not (NonSem trial). The regularity of oscillatory signals (8-30 Hz) during the retention period was found to be lower in NonSem than Sem trials, indicating that memorizing words unrelated to each other induced a non-harmonic (irregular) waveform in the temporal cortex. These results suggest that (i) semantic features of a word are retained as a set of neural oscillations at specific frequencies and (ii) memorizing words sharing a common semantic feature produces harmonic brain responses through a resonance or integration (sharing) of the oscillatory signals.Feb. 2024, NPJ science of learning, 9(1) (1), 6 - 6, English, International magazineScientific journal
- Exploratory research on genetic polymorphisms associated with positive empathy and trait forgivingness among the Japanese.OBJECTIVES: Previous studies have indicated that good human relationships contribute significantly to subjective well-being. We recently focused on two important ways of developing good interpersonal relationships: positive empathy, which focuses on the happiness of other people, and trait forgivingness, a tendency to forgive others. We novelly conducted an exploratory genome-wide association study (GWAS) to identify candidate gene polymorphisms associated with positive empathy and trait forgivingness among the Japanese. MATERIAL AND METHODS: We for the first time identified several genetic polymorphisms associated with positive empathy and trait forgivingness through the GWAS based on a small sample population and relatively low threshold. We subsequently validated three genetic polymorphisms from these candidate genes using a real-time polymerase chain reaction system. RESULTS: The results demonstrated that polymorphism in the vomeronasal type-1 receptor 1 (VN1R1) (rs61744949), a putative human pheromone receptor, is associated with positive empathy. In addition, genetic polymorphisms in the 5-hydroxytryptamine (serotonin) receptor 7 (HTR7: rs77843021) and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, epsilon (YWHAE: rs9908013), which are associated with dopamine and serotonin biosynthesis, are associated with trait forgivingness. CONCLUSION: This study novelly illustrated the influence of the genetic polymorphism in VN1R1 on positive empathy and that of genetic polymorphisms in HTR7 and YWHAE on trait forgivingness. It identified a relationship between previously unreported genetic polymorphisms and the necessary abilities for developing good human relationships. This will significantly impact future research on positive psychology and social psychology.Dec. 2023, Neuro endocrinology letters, 44(8) (8), 506 - 516, English, International magazineScientific journal
- Abstract Integrating visual and auditory information is an important ability in various cognitive processes, although its neural mechanisms remain unclear. Several studies indicated a close relationship between one's temporal binding window (TBW) for audio–visual interaction and his/her alpha rhythm in the brain (individual alpha frequency or IAF). A recent study by Buergers and Noppeney [Buergers, S., & Noppeney, U. The role of alpha oscillations in temporal binding within and across the senses. Nature Human Behaviour, 6, 732–742, 2022], however, challenged this view using a new approach to analyze behavioral data. Conforming to the same procedures by Buergers and Noppeney [Buergers, S., & Noppeney, U. The role of alpha oscillations in temporal binding within and across the senses. Nature Human Behaviour, 6, 732–742, 2022], here, I analyzed the data of my previous study and examined a relationship between TBW and IAF. In contrast to Buergers and Noppeney [Buergers, S., & Noppeney, U. The role of alpha oscillations in temporal binding within and across the senses. Nature Human Behaviour, 6, 732–742, 2022], a significant correlation was found between occipital IAF and a new behavioral measure of TBW. Some possibilities that caused these opposing results, such as a variability of “alpha band” across studies and a large inter-individual difference in magnitude of the fission illusion, are discussed.MIT Press, Mar. 2023, Journal of Cognitive Neuroscience, in press, 1 - 6, English[Refereed]Scientific journal
- Presenting one flash with two beeps induces a perception of two flashes (audio-visual [AV] fission illusion), while presenting two flashes with one beep induces a perception of one flash (fusion illusion). Although previous studies showed a relationship between the frequency of the alpha rhythm (alpha cycle) and one's susceptibility to the fission illusion, the relationship between neural oscillations and the fusion illusion is unknown. Using electroencephalography, here I investigated the frequency of oscillatory signals in the pre-stimulus period and found a significant correlation between the beta rhythm and the fusion illusion; specifically, participants with a lower beta frequency showed a larger fusion illusion. These data indicate two separate time windows of AV integration in the human brain, one defined by the alpha cycle (fission) and another defined by the beta cycle (fusion).Aug. 2022, Psychophysiology, 59(8) (8), e14041, English, International magazineScientific journal
- Springer Science and Business Media LLC, Jun. 2022, Adaptive Human Behavior and Physiology, 8(3) (3), 281 - 295Scientific journal
- Previous studies have shown that a rate of temporal decline in visual working memory (vWM) highly depends on a number of memory items. When people retain the information of many (≥ 4) stimuli simultaneously, their memory representations are fragile and rapidly degrade within 2-3 s after an offset (called the "competition" among memory items). When a memory load is low (1 or 2 items), in contrast, the fidelity of vWM is preserved for a longer time because focused attention to the small number of items prevents the temporal degradation. In the present study, we explored neural correlates of this load-dependent decline of vWM in the human brain. Using electroencephalography and a classical change-detection task, we recorded neural measures of vWM that have been reported previously, such as the contralateral delay activity (CDA) and a suppression of alpha power (8-12 Hz). Results indicated that the load-dependent decline of vWM was more clearly reflected in the change in power and speed of alpha/beta rhythm than CDA, suggesting a close relationship of those signals to an attention-based preservation of WM fidelity.2022, Cerebral cortex communications, 3(2) (2), tgac015, English, International magazineScientific journal
- Previous studies in population genetics have proposed that the Y-chromosomal (Y-DNA) haplogroup D ancestor likely originated from Africa. The haplogroup D branch next started Out-of-Africa migration, rapidly expanded across Eurasia, and later diversified in East Asia. Y-DNA haplogroup D-M55, one of the branches of haplogroup D, is only found in modern Japanese males, suggesting that individuals with Y-DNA haplogroup D migrated from the Eurasian continent. Based on previous observations, Y-DNA haplogroup D is expected to be associated with some male characteristics including personality. Therefore, this study investigated whether the Y-DNA haplogroup D-M55 is associated with several physiological and psychological characteristics, including exploratory motivation and human relationship-related perception. We recruited Japanese young adult males and females and investigated the association between Y-DNA haplogroup D-M55, physiological [body mass index (BMI)], and several psychological parameters [perceived number of close friends, behavioral inhibition system/behavioral activation system (BIS/BAS), perceived happiness, and perceived loneliness]. The results indicated that males with haplogroup D-M55 had a higher BMI and more close friends, compared with non-carrier males. Additional multiple regression analyses, which tested the hypothesis that haplogroup D-M55 predicts BMI and perceived number of close friends, confirmed our hypothesis, even after controlling for the potentially confounding variables of age and sex. We also analyzed the gene–gene interaction between haplogroup D-M55 and an autosomal gene polymorphism associated with BMI and human relationships, such as the dopamine D2 receptor gene (Frontiers Media SA, Dec. 2021, Frontiers in Behavioral Neuroscience, 15
DRD2 : rs1800497). Results showed gene–gene interactions between haplogroups D-M55 andDRD2 in BMI. Based on these findings, it is demonstrated that Y-DNA haplogroup D is associated with human personality.Scientific journal - Wiley, Oct. 2021, Japanese Psychological ResearchScientific journal
- Wiley, Aug. 2021, Japanese Psychological ResearchScientific journal
- Psychologia Society, Jul. 2021, PSYCHOLOGIA, 63(2) (2), 137 - 150Scientific journal
- Springer Science and Business Media LLC, May 2021, Culture and BrainScientific journal
- Prior research has found that East Asians are less willing than Westerners to seek social support in times of need. What factors account for this cultural difference? Whereas previous research has examined the mediating effect of relational concern, we predicted that empathic concern, which refers to feeling sympathy and concern for people in need and varies by individuals from different cultures, would promote support seeking. We tested the prediction in two studies. In Study 1, European Canadians reported higher empathic concern and a higher frequency of support seeking, compared to the Japanese participants. As predicted, cultural differences in social support seeking were influenced by empathic concern. In Study 2, both empathic concern and relational concern mediated cultural differences in support seeking. Japanese with lower empathic concern but higher relational concern were more reluctant than European Americans to seek social support during stressful times. Finally, loneliness, which was more prevalent among the Japanese than among the European Americans, was partially explained by social support seeking.2021, PloS one, 16(12) (12), e0262001, English, International magazineScientific journal
- Visual working memory (vWM) is an important ability required for various cognitive tasks although its neural underpinnings remain unclear. While many studies have focused on theta (4-7 Hz) and gamma (> 30 Hz) rhythms as a substrate of vWM, here we show that temporal signals embedded in alpha (8-12 Hz) and beta (13-30 Hz) bands can be a good predictor of vWM capacity. Neural activity of healthy human participants was recorded with magnetoencephalography when they performed a classical vWM task (change detection). We analyzed changes in inter-peak intervals (IPIs) of oscillatory signals along with an increase in WM load (a number of to-be-memorized items, 1-6). Results showed a load-dependent reduction of IPIs in the parietal and frontal regions, indicating that alpha/beta rhythms became faster when multiple items were stored in vWM. Furthermore, this reduction in IPIs was positively correlated with individual vWM capacity, especially in the frontal cortex. Those results indicate that vWM is represented as a change in oscillation frequency in the human cerebral cortex.Nov. 2020, NeuroImage, 222, 117294 - 117294, English, International magazineScientific journal
- Early-life environments have been associated with various social behaviors, including trust, in late adolescence and adulthood. Given that the oxytocin receptor gene polymorphism (OXTR rs53576) moderates the impact of childhood experience on social behaviors, in the present study, we examined the main effect of childhood adversity through a self-report measure and its interactions with OXTR rs53576 on general trust among 203 Japanese and 200 European Canadian undergraduate students. After controlling for the effect of culture, the results indicated that childhood adversity had a negative association with general trust, and that OXTR rs53576 moderated the impact of childhood adversity on general trust. Specifically, the negative association between childhood adversity and general trust is only significant among homozygote A-allele carriers. These findings demonstrated that OXTR rs53576 moderated the relations between childhood experiences and social functioning in early adulthood.Nov. 2020, Psychoneuroendocrinology, 121, 104840 - 104840, English, International magazineScientific journal
- Springer Science and Business Media LLC, Feb. 2020, Culture and Brain, 9(1) (1), 20 - 34[Refereed]Scientific journal
- It is widely known that emotionally-arousing pictures are perceived more rapidly than non-arousing pictures, although neural underpinnings of this effect remain unclear. Using electroencephalography, we presently measured neural oscillatory rhythms of the human brain in response to various emotional images from the International Affective Picture System. We found that an oscillation frequency in the alpha-to-beta band (8-30 Hz) became higher over the parietal cortex when participants viewed emotionally-arousing than non-arousing pictures. This modulation of neural rhythms was also observed in a valence dimension; emotionally-negative pictures induced faster neural rhythm than emotionally-positive pictures. Those results were consistent with previous studies reporting a speeded perception of high-arousing and negative stimuli (e.g. snakes and spiders) and further provided neural evidence for an adaptive function of emotion to accelerate the processing of potentially-dangerous stimuli.Jan. 2020, Biological psychology, 149, 107787 - 107787, English, International magazineScientific journal
- Neural oscillatory signals has been associated with many high-level functions (e.g. attention and working memory), because they reflect correlated behaviors of neural population that would facilitate the information transfer in the brain. On the other hand, a decreased power of oscillation (event-related desynchronization, ERD) has been associated with an irregular state in which many neurons behave in an uncorrelated manner. In contrast to this view, here we show that the human ERD is linked to the increased regularity of oscillatory signals. Using magnetoencephalography, we found that presenting a visual stimulus not only induced a decrease in power of alpha (8-12 Hz) to beta (13-30 Hz) rhythms in the contralateral visual cortex but also reduced the mean and variance of their inter-peak intervals (IPIs). This indicates that the suppressed alpha/beta rhythms became faster (reduced mean) and more regular (reduced variance) during visual stimulation. The same changes in IPIs, especially those of beta rhythm, were observed when subjects allocated their attention to a contralateral visual field. Those results revealed a new role of the event-related decrease in alpha/beta power and further suggested that our brain regulates and accelerates a clock for neural computations by actively suppressing the oscillation amplitude in task-relevant regions.May 2019, NeuroImage, 191, 225 - 233, English, International magazineScientific journal
- 2019, Canadian Journal of Behavioural Science, 51(4) (4), 290 - 295, EnglishIs collectivistic forgiveness different from individualistic forgiveness? Dispositional correlates of trait forgivingness in Canada and Japan[Refereed]Scientific journal
- Oct. 2018, Human brain mapping[Refereed]
- Some researchers in aesthetics assume visual features related to aesthetic perception (e.g. golden ratio and symmetry) commonly embedded in masterpieces. If this is true, an intriguing hypothesis is that the human brain has neural circuitry specialized for the processing of visual beauty. We presently tested this hypothesis by combining a neuroimaging technique with the repetition suppression (RS) paradigm. Subjects (non-experts in art) viewed two images of sculptures sequentially presented. Some sculptures obeyed the golden ratio (canonical images), while the golden proportion were impaired in other sculptures (deformed images). We found that the occipito-temporal cortex in the right hemisphere showed the RS when a canonical sculpture (e.g. Venus de Milo) was repeatedly presented, but not when its deformed version was repeated. Furthermore, the right parietal cortex showed the RS to the canonical proportion even when two sculptures had different identities (e.g. Venus de Milo as the first stimulus and David di Michelangelo as the second), indicating that this region encodes the golden ratio as an abstract rule shared by different sculptures. Those results suggest two separate stages of neural processing for aesthetic information (one in the occipito-temporal and another in the parietal regions) that are hierarchically arranged in the human brain.Springer New York LLC, Jun. 2018, Brain Topography, 1 - 13, English[Refereed]Scientific journal
- Mar. 2018, Neuroscience research, 128, 33 - 39[Refereed]
- 2018, PloS one, 13(12) (12), e0209552[Refereed]
- The present study investigated the association between a polymorphism of the serotonin 2A receptor (5-HT2AR) gene and the form of impulsive choice known as delay discounting. Using a hypothetical situation, we asked Japanese participants to choose between receiving (or paying) a different amount of money immediately or with a specified delay (one week, two weeks, one month, six months, one year, five years, or 25 years), and estimated the parameters of intertemporal choice models (exponential, hyperbolic, hyperbolic with exponent, and quasi hyperbolic). Regardless of the genotypes, the hyperbolic with exponent model, which always indicated minimum AICc (Akaike Information Criterion with small sample correction), fitted better the observed data than the other models. Future gains were discounted more steeply than future losses. Moreover, as expected, individuals with the AA genotype of the 5-HT2AR A-1438G polymorphism discounted the future more steeply than did individuals with the GG genotype, although this effect was limited to only gains. The findings implied individual differences based on the A-1438G polymorphism in the modulation of serotonin in the reward valuation underlying delay discounting. (C) 2017 Elsevier Ltd. All rights reserved.PERGAMON-ELSEVIER SCIENCE LTD, Jan. 2018, PERSONALITY AND INDIVIDUAL DIFFERENCES, 121, 193 - 199, English[Refereed]Scientific journal
- Happiness is regarded as one of the most fundamental human goals. Given recent reports that positive feelings are contagious (e.g., the presence of a happy person enhances others' happiness) because of the human ability to empathize (i.e., sharing emotions), empathic ability may be a key factor in increasing one's own subjective level of happiness. Based on previous studies indicating that a single nucleotide polymorphism in the serotonin 2A receptor gene [HTR2A rs6311 guanine (G) vs. adenine (A)] is associated with sensitivity to emotional stimuli and several mental disorders such as depression, we predicted that the polymorphism might be associated with the effect of sharing happiness. To elucidate the neural and genetic correlates of the effect of sharing happiness, we first performed functional magnetic resonance imaging (fMRI) during a "happy feelings" evocation task (emotional event imagination task), during which we manipulated the valence of the imagined event (positive, neutral, or negative), as well as the presence of a friend experiencing a positive-valence event (presence or absence). We recruited young adult women for this fMRI study because empathic ability may be higher in women than in men. Participants felt happier (p < 0.01) and the mentalizing/theory-of-mind network, which spans the medial prefrontal cortex, temporoparietal junction, temporal poles, and precuneus, was significantly more active (p < 0.05) in the presence condition than in the absence condition regardless of event valence. Moreover, participants with the GG (p < 0.01) and AG (p < 0.05) genotypes of HTR2A experienced happier feelings as well as greater activation of a part of the mentalizing/theory-of-mind network (p < 0.05) during empathy for happiness (neutral/presence condition) than those with the AA genotype. In a follow-up study with a vignette-based questionnaire conducted in a relatively large sample, male and female participants were presented with the same imagined events wherein their valence and the presence of a friend were manipulated. Results showed genetic differences in happiness-related empathy regardless of sex (p < 0.05). Findings suggest that HTR2A polymorphisms are associated with the effect of sharing happiness by modulating the activity of the mentalizing/theory-of-mind network.Frontiers Media S.A., Dec. 2017, Frontiers in Neuroscience, 11, 718, English[Refereed]Scientific journal
- Although human saliva contains the monoamine serotonin, which plays a key role in the modulation of emotional states, the association between salivary serotonin and empathic ability remains unclear. In order to elucidate the associations between salivary serotonin levels, trait empathy, and the sharing effect of emotions (i.e., sharing emotional experiences with others), we performed a vignette-based study. Participants were asked to evaluate their happiness when they experience several hypothetical life events, whereby we manipulated the valence of the imagined event (positive, neutral, or negative), as well as the presence of a friend (absent, positive, or negative). Results indicated that the presence of a happy friend significantly enhanced participants' happiness. Correlation analysis demonstrated that salivary serotonin levels were negatively correlated with happiness when both the self and friend conditions were positive. Correlation analysis also indicated a negative relationship between salivary serotonin levels and trait empathy (particularly in perspective taking), which was measured by the Interpersonal Reactivity Index. Furthermore, an exploratory multiple regression analysis suggested that mothers' attention during childhood predicted salivary serotonin levels. Our findings indicate that empathic abilities and the social sharing of happiness decreases as a function of salivary serotonin levels.PUBLIC LIBRARY SCIENCE, Jul. 2017, PLOS ONE, 12(7) (7), e0180391, English[Refereed]Scientific journal
- Although many studies have reported a distortion of subjective (internal) time during preparation and execution of actions, it is highly controversial whether actions cause a dilation or compression of time. In the present study, we tested a hypothesis that the previous controversy (dilation vs. compression) partly resulted from a mixture of two types of sensory inputs on which a time length was estimated; some studies asked subjects to measure the time of presentation for a single continuous stimulus (Stimulus period, e.g. the duration of a long-lasting visual stimulus on a monitor) while others required estimation of a period without continuous stimulations (no-stimulus period, e.g. an inter-stimulus interval between two flashes). Results of our five experiments supported this hypothesis, showing that action preparation induced a dilation of a stimulus period, whereas a no-stimulus period was not subject to this dilation and sometimes can be compressed by action preparation. Those results provided a new insight into a previous view assuming a uniform dilation or compression of subjective time by actions. Our findings about the distinction between stimulus and no-stimulus periods also might contribute to a resolution of mixed results (action-induced dilation vs. compression) in a previous literature. (C) 2016 Elsevier B.V. All rights reserved.ELSEVIER SCIENCE BV, Mar. 2017, COGNITION, 160, 51 - 61, English[Refereed]Scientific journal
- ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, Jul. 2016, INTERNATIONAL JOURNAL OF PSYCHOLOGY, 51, 316 - 316, EnglishAssociation between social sensitivity genes and interdependence in Japanese[Refereed]
- Attention facilitates conscious perception of a visual stimulus at an attended location. Interestingly, a recent study (using the Posner spatial-cueing task) reported that attention facilitated conscious perception even when it was cued after a stimulus was gone (postcued-attention or retroperception effect). Here, we show that this effect can be induced without any contribution of attention. Contrary to previous situations, we fixed a position of a target (Gabor patch) and cue (luminance change of a circle encompassing the target) across trials so that subjects always could allocate their full attention to the target position. The cue (luminance change) improved objective and subjective visibility of the nearby target even when it was given similar to 200 ms after the target's offset. This retrospective improvement was diminished when a shape of the cue was changed from a circle to a dot pattern, suggesting that the improvement emerged from a visual interaction (combinations of shapes) between the circular cue and target. Those results indicated that a local visual interaction between the target and cue is sufficient to trigger consciousness of the target, revealing a new type of retroperception effect mediated by sensory (nonattentional) mechanisms.ASSOC RESEARCH VISION OPHTHALMOLOGY INC, May 2016, JOURNAL OF VISION, 16(7) (7), 3, English[Refereed]Scientific journal
- When we encounter someone we dislike, we may momentarily display a reflexive disgust expression, only to follow-up with a forced smile and greeting. Our daily lives are replete with a mixture of true and fake expressions. Nevertheless, are these fake expressions really effective at hiding our true emotions? Here we show that brief emotional changes in the eyes (micro-expressions, thought to reflect true emotions) can be successfully concealed by follow-up mouth movements (e.g. a smile). In the same manner as backward masking, mouth movements of a face inhibited conscious detection of all types of micro-expressions in that face, even when viewers paid full attention to the eye region. This masking works only in a backward direction, however, because no disrupting effect was observed when the mouth change preceded the eye change. These results provide scientific evidence for everyday behaviours like smiling to dissemble, and further clarify a major reason for the difficulty we face in discriminating genuine from fake emotional expressions.NATURE PUBLISHING GROUP, Feb. 2016, SCIENTIFIC REPORTS, 6, 22049, English[Refereed]Scientific journal
- Recent studies argue that strongly-motivated positive emotions (e.g. desire) narrow a scope of attention. This argument is mainly based on an observation that, while humans normally respond faster to global than local information of a visual stimulus (global advantage), positive affects eliminated the global advantage by selectively speeding responses to local (but not global) information. In other words, narrowing of attentional scope was indirectly evidenced by the elimination of global advantage (the same speed of processing between global and local information). No study has directly shown that strongly-motivated positive affects induce faster responses to local than global information while excluding a bias for global information (global advantage) in a baseline (emotionally-neutral) condition. In the present study, we addressed this issue by eliminating the global advantage in a baseline (neutral) state. Induction of positive affects under this state resulted in faster responses to local than global information. Our results provided direct evidence that positive affects in high motivational intensity narrow a scope of attention.NATURE PUBLISHING GROUP, Jan. 2016, SCIENTIFIC REPORTS, 6, 19136, English[Refereed]Scientific journal
- To efficiently process a cluttered scene, the visual system analyzes statistical properties or regularities of visual elements embedded in the scene. It is controversial, however, whether those scene analyses could also work for stimuli unconsciously perceived. Here we show that our brain performs the unconscious scene analyses not only using a single featural cue (e.g., orientation) but also based on conjunctions of multiple visual features (e.g., combinations of color and orientation information). Subjects foveally viewed a stimulus array (duration: 50 ms) where 4 types of bars (red-horizontal, red-vertical, green-horizontal, and green-vertical) were intermixed. Although a conscious perception of those bars was inhibited by a subsequent mask stimulus, the brain correctly analyzed the information about color, orientation, and color-orientation conjunctions of those invisible bars. The information of those features was then used for the unconscious configuration analysis (statistical processing) of the central bars, which induced a perceptual bias and illusory feature binding in visible stimuli at peripheral locations. While statistical analyses and feature binding are normally 2 key functions of the visual system to construct coherent percepts of visual scenes, our results show that a high-level analysis combining those 2 functions is correctly performed by unconscious computations in the brain.AMER PSYCHOLOGICAL ASSOC, Jun. 2015, JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE, 41(3) (3), 639 - 648, English[Refereed]Scientific journal
- Discriminating a direction of frequency change is an important ability of the human auditory system, although temporal dynamics of neural activity underlying this discrimination remains unclear. In the present study, we recorded auditory-evoked potentials when human subjects explicitly judged a direction of a relative frequency change between two successive tones. A comparison of two types of trials with ascending and descending tone pairs revealed that neural activity discriminating a direction of frequency changes appeared as early as the P1 component of auditory-evoked potentials (latency 50 ms). Those differences between the ascending and descending trials were also observed in subsequent electroencephalographic components such as the N1 (100 ms) and P2 (200 ms). Furthermore, amplitudes of the P2 were significantly modulated by behavioral responses (upward/downward judgments) of subjects in the direction discrimination task, while those of the P1 were not. Those results indicate that, while the neural responses encoding a direction of frequency changes can be observed in an early component of electroencephalographic responses (50 ms after the change), the activity associated (correlated) with behavioral judgments evolves over time, being shaped in a later time period (around 200 ms) of the auditory processing.SPRINGER, May 2015, BRAIN TOPOGRAPHY, 28(3) (3), 437 - 444, English[Refereed]Scientific journal
- Many previous theories of perceptual awareness assume that a conscious representation of a stimulus is created from sensory information carried by an onset (appearance) of the stimulus. In contrast, here we provide behavioral and neural evidence for a new phenomenon in which conscious perception is directly triggered by an offset (disappearance) of a stimulus. When a stimulus made invisible by inter-ocular suppression physically disappeared from a screen, subjects reported an appearance (not disappearance) of that stimulus, correctly reporting a color of the disappeared stimulus. Measurements of brain activity further confirmed that the physical offset of an invisible stimulus evoked neural activity reflecting conscious perception of that stimulus. Those results indicate a new role of a stimulus offset to facilitate (rather than inhibit) an emergence of consciousness. (C) 2015 Elsevier Ltd. All rights reserved.ELSEVIER MASSON, Apr. 2015, CORTEX, 65, 159 - 172, English[Refereed]Scientific journal
- Grapheme-color synesthesia is a phenomenon in which achromatic letters/digits automatically induce particular colors. When multiple letters are integrated into a word, some synesthetes perceive that all those letters are changed into the same color, reporting lexical color to that word. Previous psychological studies found several "rules" that determine those lexical colors. The colors to most words are determined by the first letters of the words, while some words in ordinal sequences have their specific colors. Recent studies further reported the third case where lexical colors might be influenced by semantic information of words. Although neural mechanisms determining those lexical colors remained unknown, here we identified three separate neural systems in the synesthete's brain underlying three rules for illusory coloring of words. In addition to the occipitotemporal and parietal regions previously found to be associated with the grapheme-color synesthesia, neural systems for lexical coloring extended to linguistic areas in the left inferior frontal and anterior temporal regions that were engaged in semantic analyses of words. Those results indicate an involvement of wider and higher neural networks than previously assumed in a production of synesthetic colors to visual stimuli and further showed a multiplicity of synesthetic mechanisms represented in the single brain. (C) 2014 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Jul. 2014, NEUROIMAGE, 94, 360 - 371, English[Refereed]Scientific journal
- Whether face gender perception is processed by encoding holistic (whole) or featural (parts) information is a controversial issue. Although neuroimaging studies have identified brain regions related to face gender perception, the temporal dynamics of this process remain under debate. Here, we identified the mechanism and temporal dynamics of face gender perception. We used stereoscopic depth manipulation to create two conditions: the front and behind condition. In the front condition, facial patches were presented stereoscopically infront of the occluder and participants perceived them as disjoint parts (featural cues). In the behind condition, facial patches were presented stereoscopically behind the occluder and were amodally completed and unified in a coherent face (holisticcues). We performed three behavioral experiments and one electro encephalography experiment, and compared the results of the front and behind conditions. We found faster reaction times (RTs) in the behind condition compared with the front, and observed priming effects and after effects only in the behind condition. Moreover, the EEG experiment revealed that face gender perception is processed in the relatively late phase of visual recognition( 200-285 ms). Our results indicate that holistic information is critical for face gender perception, and that this process occurs witha relatively late latency.FRONTIERS RESEARCH FOUNDATION, Jun. 2014, FRONTIERS IN HUMAN NEUROSCIENCE, 8(JUNE) (JUNE), English[Refereed]Scientific journal
- Growing evidence indicates a moderate but significant relationship between processing speed in visuo-cognitive tasks and general intelligence. On the other hand, findings from neuroscience proposed that the primate visual system consists of two major pathways, the ventral pathway for objects recognition and the dorsal pathway for spatial processing and attentive analysis. Previous studies seeking for visuo-cognitive factors of human intelligence indicated a significant correlation between fluid intelligence and the inspection time (IT), an index for a speed of object recognition performed in the ventral pathway. We thus presently examined a possibility that neural processing speed in the dorsal pathway also represented a factor of intelligence. Specifically, we used the mental rotation (MR) task, a popular psychometric measure for mental speed of spatial processing in the dorsal pathway. We found that the speed of MR was significantly correlated with intelligence scores, while it had no correlation with one's IT (recognition speed of visual objects). Our results support the new possibility that intelligence could be explained by two types of mental speed, one related to object recognition (IT) and another for manipulation of mental images (MR).PUBLIC LIBRARY SCIENCE, May 2014, PLOS ONE, 9(5) (5), e97429, English[Refereed]Scientific journal
- Previous research using averted (e.g., leftward or rightward) gaze indicates that gaze perception requires a focus of attention. However, direct gaze, compared with averted gaze, is processed in the brain preferentially and enhances cognitive functions. Thus, it is necessary to use direct gaze to investigate whether gaze perception is possible without focused attention. We conducted a dual-task paradigm in which attention was drawn away from gaze. Results showed performance on gaze-direction discrimination (direct vs. averted gaze) in the dual-task condition was only slightly lower than in the single-task condition; participants were able to discriminate direct from averted gaze without focusing their attention in a similar manner to when they did focus their attention. In contrast, when participants discriminated between averted gazes (leftward and rightward), performance dropped to near-chance levels. It was concluded that gaze perception does not require a focus of attention for direct gaze.NATURE PUBLISHING GROUP, Jan. 2014, SCIENTIFIC REPORTS, 4, 3858, English[Refereed]Scientific journal
- Target identification is related to the frequency with which targets appear at a given location, with greater frequency enhancing identification. This phenomenon suggests that location probability learned through repeated experience with the target modulates cognitive processing. However, it remains unclear whether attentive processing of the target is required to learn location probability. Here, we used a dual-task paradigm to test the location probability effect of attended and unattended stimuli. Observers performed an attentionally demanding central-letter task and a peripheral-bar discrimination task in which location probability was manipulated. Thus, we were able to compare performance on the peripheral task when attention was fully engaged to the target (single-task condition) versus when attentional resources were drawn away by the central task (dual-task condition). The location probability effect occurred only in the single-task condition, when attention resources were fully available. This suggests that location probability learning requires attention to the target stimuli.PION LTD, 2014, PERCEPTION, 43(4) (4), 344 - 350, English[Refereed]Scientific journal
- The primate visual system is assumed to comprise two main pathways: a ventral pathway for shape and color perception and a dorsal pathway for spatial processing and visuomotor control. Previous studies consistently reported strong activation in the dorsal pathway (especially in the inferior parietal region) induced by manipulable object images such as tools. However, it is controversial whether the dorsal pathway retains this preferential activity to tool images under unconscious perception. In the present study, we used magnetoencephalography (MEG) and investigated spatio-temporal dynamics of neural responses to visible and invisible tool images. A presentation of visible tool images elicited a strong neural response over the parietal regions in the left hemisphere peaking at 400 msec. This response unique to the processing of tool information in the left parietal regions was still observed when conscious perception of tool images was inhibited by interocular suppression. Furthermore, analyses of neural oscillation signals revealed a suppression of mu rhythm (8-13 Hz), a neural index of movement execution or imagery, induced by both visible and invisible tools. Those results indicated that the neural circuit to process the tool information was preserved under unconscious perception, highlighting an implicit aspect of the dorsal pathway. (C) 2013 Elsevier Ltd. All rights reserved.ELSEVIER MASSON, Jan. 2014, CORTEX, 50, 100 - 114, English[Refereed]Scientific journal
- Humans detect faces with direct gaze more rapidly than they do faces with averted gaze. Evidence suggests that the visual information of faces with direct gaze reaches conscious awareness faster than that of faces with averted gaze. This suggests that faces with direct gaze are effectively processed in the brain before they reach conscious awareness however, it is unclear how the unconscious perception of faces with direct gaze is processed in the brain. To address this unanswered question, we recorded event-related potentials while observers viewed faces with direct or averted gaze that were either visible or rendered invisible during continuous flash suppression. We observed that invisible faces with direct gaze elicited significantly larger negative deflections than did invisible faces with averted gaze at 200, 250, and 350. ms over the parietofrontal electrodes, whereas we did not observe such effects when facial images were visible. Our results suggest that the visual information of faces with direct gaze is preferentially processed in the brain when they are presented unconsciously. © 2013 Elsevier Ltd.Jun. 2013, Neuropsychologia, 51(7) (7), 1161 - 1168, English[Refereed]Scientific journal
- While viewing works of art in galleries, we evaluate them by integrating at least two types of information: their visual properties (e.g., colors, symmetry, and proportion) and contextual information accompanying them (e.g., titles and names of artists). How rapidly the brain integrates visual and contextual information of artworks remains to be investigated. Using electroencephalography (EEG), we investigated neural activity when subjects with no professional experience in art viewed images of sculptures (masterpieces from the Classical and Renaissance periods, characterized by a canonical proportion of the golden ratio) and performed a five-scale rating of how appealing they were. At the beginning of each trial, we manipulated the expectations of the subjects for an upcoming sculpture by presenting information about its authenticity (either "genuine" or "fake"), although all images were actually taken from genuine artworks. The image of the sculpture was then presented, either in its original proportion or after being deformed by a photo-editing software. This 2 x 2 factorial design enabled us to identify whether each component of the EEG response was sensitive to contextual information (genuine or fake), visual information (original or deformed), or both. Results revealed that amplitudes of a positive EEG component emerging at 200-300 ms after the presentation of the artworks (mainly distributed over the parietal cortex) were significantly modulated by both visual and contextual factors, indicating a rapid integration of these two types of information in the brain. (C) 2013 Elsevier Ltd. All rights reserved.PERGAMON-ELSEVIER SCIENCE LTD, May 2013, NEUROPSYCHOLOGIA, 51(6) (6), 1077 - 1084, English[Refereed]Scientific journal
- A previous study reported the misbinding illusion in which visual features belonging to overlapping sets of items were erroneously integrated (Wu, Kanai, & Shimojo, 2004, Nature, 429, 262). In this illusion, central and peripheral portions of a transparent motion field combined color and motion in opposite fashions. When observers saw such stimuli, their perceptual color-motion bindings in the periphery were re-arranged in such a way as to accord with the bindings in the central region, resulting in erroneous color-motion pairings (misbinding) in peripheral vision. Here we show that this misbinding illusion is also seen in the binding of color and orientation. When the central field of a stimulus array was composed of objects that had coherent (regular) color-orientation pairings, subjective color-orientation bindings in the peripheral stimuli were automatically altered to match the coherent pairings of the central stimuli. Interestingly, the illusion was induced only when all items in the central field combined color and orientation in an orthogonal fashion (e.g. all red bars were horizontal and all green bars were vertical). If this orthogonality was disrupted (e.g. all red and green bars were horizontal), the central field lost its power to induce the misbinding illusion in the peripheral stimuli. The original misbinding illusion study proposed that the illusion stemmed from a perceptual extrapolation that resolved peripheral ambiguity with clear central vision. However, our present results indicate that visual analyses of the correlational structure between two features (color and orientation) are critical for the illusion to occur, suggesting a rapid integration of multiple featural cues in the human visual system. (c) 2013 Elsevier Ltd. All rights reserved.PERGAMON-ELSEVIER SCIENCE LTD, Apr. 2013, VISION RESEARCH, 82, 58 - 65, English[Refereed]Scientific journal
- Many studies using electroencephalography consistently reported a larger N170 (N1) response in the visual cortices to inverted than upright face images (the face inversion effect in N1, FIE-N1). Here we report this robust effect is diminished and even reversed when face stimuli are processed unconsciously. We measured visual-evoked potentials to neutral faces either visible or rendered invisible by an inter-ocular suppression. In visible condition, we observed a larger N1 to inverted than upright faces, which replicated the traditional FIE-N1. When those faces became invisible, however, neural responses to the inverted faces were greatly reduced compared to visible condition, whereas those to the invisible upright faces were relatively preserved. Consequently, N1 amplitudes were found to be larger in upright, rather than inverted, faces in invisible condition, which was opposite to the traditional FIE-N1 (upright< inverted) in visible condition. Those results highlighted a special mechanism in the brain for the processing of the upright, but not inverted, face (e.g. fusiform face area) that retains vigorous responses even when the face becomes invisible. © 2012 Elsevier Ltd.Feb. 2013, Neuropsychologia, 51(3) (3), 400 - 409, English[Refereed]Scientific journal
- Shifts in spatial attention can be induced by the gaze direction of another. However, it is unclear whether gaze direction influences the allocation of attention by reflexive or voluntary orienting. The present study was designed to examine which type of attentional orienting is elicited by gaze direction. We conducted two experiments to answer this question. In Experiment 1, we used a modified Posner paradigm with gaze cues and measured microsaccades to index the allocation of attention. We found that microsaccade direction followed cue direction between 200 and 400 ms after gaze cues were presented. This is consistent with the latencies observed in other microsaccade studies in which voluntary orienting is manipulated, suggesting that gaze direction elicits voluntary orienting. However, Experiment 1 did not separate voluntary and reflexive orienting directionally, so in Experiment 2, we used an anticue task in which cue direction (direction to allocate attention) was the opposite of gaze direction (direction of gaze in depicted face). The results in Experiment 2 were consistent with those from Experiment 1. Microsaccade direction followed the cue direction, not gaze direction. Taken together, these results indicate that the shift in spatial attention elicited by gaze direction is voluntary orienting.SPRINGER, Nov. 2012, EXPERIMENTAL BRAIN RESEARCH, 223(2) (2), 291 - 300, English[Refereed]Scientific journal
- From which regions of the brain do conscious representations of visual stimuli emerge? This is an important but controversial issue in neuroscience because some studies have reported a major role of the higher visual regions of the ventral pathway in conscious perception, whereas others have found neural correlates of consciousness as early as in the primary visual areas and in the thalamus. One reason for this controversy has been the difficulty in focusing on neural activity at the moment when conscious percepts are generated in the brain, excluding any bottom-up responses (not directly related to consciousness) that are induced by stimuli. In this study, we address this issue with a new approach that can induce a rapid change in conscious perception with little influence from bottom-up responses. Our results reveal that the first consciousness-related activity emerges from the higher visual region of the ventral pathway. However, this activity is rapidly diffused to the entire brain, including the early visual cortex. These results thus integrate previous "higher" and "lower" views on the emergence of neural correlates of consciousness, providing a new perspective for the temporal dynamics of consciousness.MIT PRESS, Oct. 2012, JOURNAL OF COGNITIVE NEUROSCIENCE, 24(10) (10), 1983 - 1997, English[Refereed]Scientific journal
- When we encode faces in memory, we often do so in association with biographical information regarding the person. To examine the neural dynamics underlying such encoding processes, we devised a face recognition task and recorded cortical activity using magnetoencephalography. The task included two conditions. In the experimental condition, face stimuli were preceded by biographical information regarding the person whose face was to be memorized, whereas in the control condition, nonsense syllables were presented before face stimuli. Behavioral results indicated that the biographical information about a person facilitated the recognition memory of their face. Magnetoencephalography signals showed clear visually evoked magnetic fields mainly in the occipitotemporal cortex, in response to the face stimuli that were to be encoded. The phasic peak was observed at 100200 ms after onset of a face stimulus, which was followed by late latency deflections (200400 ms). Comparison of the signal between conditions revealed that the preceding semantic information does modulate the neuromagnetic responses to the face stimuli. This modulation occurred primarily at the late latency component in the sensors over the occipitotemporal cortex. In addition, the effects of conditions were also observed in the signals from more anterior sensors, which occurred earlier than the effects in the occipitotemporal cortex. These results provide insights into the neural dynamics underlying the encoding of faces in association with their biographical information.WILEY-BLACKWELL, Dec. 2011, EUROPEAN JOURNAL OF NEUROSCIENCE, 34(12) (12), 2043 - 2053, English[Refereed]Scientific journal
- To analyze complex scenes efficiently, the human visual system performs perceptual groupings based on various features (e.g., color and motion) of the visual elements in a scene. Although previous studies demonstrated that such groupings can be based on a single feature (e.g., either color or motion information), here we show that the visual system also performs scene analyses based on a combination of two features. We presented subjects with a mixture of red and green dots moving in various directions. Although the pairings between color and motion information were variable across the dots (e.g., one red dot moved upward while another moved rightward), subjects' perceptions of the color-motion pairings were significantly biased when the randomly paired dots were flanked by additional dots with consistent color-motion pairings. These results indicate that the visual system resolves local ambiguities in color-motion pairings using unambiguous pairings in surrounds, demonstrating a new type of scene analysis based on the combination of two featural cues.SAGE PUBLICATIONS INC, Feb. 2011, PSYCHOLOGICAL SCIENCE, 22(2) (2), 153 - 158, English[Refereed]Scientific journal
- We aimed at testing the cortical representation of complex natural sounds within auditory cortex by conducting 2 human magnetoencephalography experiments. To this end, we employed an adaptation paradigm and presented subjects with pairs of complex stimuli, namely, animal vocalizations and spectrally matched noise. In Experiment 1, we presented stimulus pairs of same or different animal vocalizations and same or different noise. Our results suggest a 2-step process of adaptation effects: first, we observed a general item-unspecific reduction of the N1m peak amplitude at 100 ms, followed by an item-specific amplitude reduction of the P2m component at 200 ms after stimulus onset for both animal vocalizations and noise. Multiple dipole source modeling revealed the right lateral Heschl's gyrus and the bilateral superior temporal gyrus as sites of adaptation. In Experiment 2, we tested for cross-adaptation between animal vocalizations and spectrally matched noise sounds, by presenting pairs of an animal vocalization and its corresponding or a different noise sound. We observed cross-adaptation effects for the P2m component within bilateral superior temporal gyrus. Thus, our results suggest selectivity of the evoked magnetic field at 200 ms after stimulus onset in nonprimary auditory cortex for the spectral fine structure of complex sounds rather than their temporal dynamics.OXFORD UNIV PRESS INC, Jun. 2008, CEREBRAL CORTEX, 18(6) (6), 1350 - 1360, English[Refereed]Scientific journal
- This is the first functional magnetic resonance imaging (fMRI) study to investigate the hemodynamic response related to somatosensory spatial discrimination, so-called two-point discrimination. During scanning, we examined two discrimination tasks using four types of electrical stimuli applied to one or two points with strong or weak intensity on the right and left forearm, respectively. In the two-point discrimination task (TPD), subjects reported whether they thought the stimulus was applied to one point or two. In the intensity discrimination task (ID), subjects were required to judge whether the stimulus was strong or weak. In each task, they pressed a button to report their choice. Comparing TPD with the control, we found activated regions in the inferior parietal lobule (IPL) around the supramarginal gyros (SMG) (Brodmann's area 40) and anterior cingulate cortex (ACC). These areas were significantly activated irrespective of the forearm stimulated. Comparing ID with the control, there were no significantly activated regions. By comparing the TPD and ID, we identified that the left IPL was significantly activated, specifically in TPD, irrespective of the forearm stimulated. In contrast, there were no significantly activated regions in the 11) task. Therefore, the left IPL is considered to play an important role in two-point discrimination. (c) 2007 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Apr. 2008, NEUROIMAGE, 40(2) (2), 852 - 858, English[Refereed]Scientific journal
- A flash is perceived to lag spatially behind a moving object even when the two retinal images are physically aligned (flash-lag effect, FLE). Here we show that this robust illusion can be diminished by a knowledge of letters in the observer's brain. When moving and flashed segments in the FLE made the shape of a Kanji letter (ideographic characters used in Japan), the magnitude of the illusory lag perceived by Japanese subjects was significantly reduced compared to when conventional geometric (nonletter) segments were used. This diminishment was not observed when a pseudo-Kanji letter was presented to Japanese subjects or when non-Japanese English-speakers (who do not have a knowledge of Kanji) saw a real Kanji letter, indicating that the reduction in the FLE was induced by a retrieval of the knowledge (shapes of letters) stored in the observer's brain. Furthermore, measurements of neural activities by magnetoencephalography showed that the initial brain response, in which the effect of the knowledge became evident, occurred as early as 160 msec after the appearance of the flashed segment. These results demonstrated a substantial influence of knowledge on the flash-lag illusion and further suggest a rapid response of the knowledge-based perceptual pathway in the human brain.M I T PRESS, Mar. 2008, JOURNAL OF COGNITIVE NEUROSCIENCE, 20(3) (3), 513 - 525, English[Refereed]Scientific journal
- The human visual system is considered to have at I east two different mechanisms for perceiving motions: one for luminance-based (first-order) motions and another for non-luminance-based (second-order) motions. In this study, we examined the perception of first- and second-order motions using four different types of stimulus cues (luminance, contrast, texture, and flicker) while using whole head magnetoencephalography (MEG) to measure human brain responses to those apparent motions. MEG responses to all stimuli were recorded from the occipito-temporal area (possibly human MT/V5+), and response properties (peak latency and amplitude) varied with stimulus cues. Further, we observed various effects of luminance-addition to the non-luminance cues on the response properties that could not be explained by the magnetic field distribution and/or the visibility of the stationary object. The results indicate that differences in response properties elicited by various stimulus cues represent differences in the neural processes underlying apparent motions with various cues. We suggest that the distinct '' preprocessing '' of each stimulus cue occurs before the common process for apparent motion, and the response property changes associated with different cues are related to differences in preprocessing that may occur in a distributed cortical network that include the striate and extrastriate visual cortex. (C) 2007 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.ELSEVIER IRELAND LTD, Oct. 2007, NEUROSCIENCE RESEARCH, 59(2) (2), 172 - 182, English[Refereed]Scientific journal
- To identify the BOLD effects related to olfaction in humans, we recorded functional magnetic resonance imaging (fMRI) scans in response intravenously instilled thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD). TPD and TTFD evoked a strong and weak odor sensation, respectively. Since we did not spray the odor stimuli directly, this method is expected to reduce the effect caused by direct stimulation of the trigeminal nerve. For the analysis of fMRI data, statistical parametric mapping (SPM2) was employed and the areas significantly activated during olfactory processing were located. Both strong and weak odorants induced brain activities mainly in the orbitofrontal gyrus (Brodmann's area: BA 11) in the left hemisphere. TPD (a strong odorant) induced activity in the subthalamic nucleus in the left hemisphere and the precentral gyrus (BA 6) and insula in the right hemisphere. TTFD (a weak odorant) induced activity in the superior frontal gyrus (BA C 11) in the right hemisphere. In both circumstances, there was an increase in blood flow at the secondary olfactory cortex (SOC) but not the primary olfactory cortex (POC), probably due to a habituation effect in the POC. From the present results, we found brain activity in not only odor-specific regions but also regions whose levels of activity were changed by an intensity difference of odor stimuli. (C) 2007 Elsevier Ireland Ltd. All rights reserved.ELSEVIER IRELAND LTD, Aug. 2007, NEUROSCIENCE LETTERS, 423(1) (1), 6 - 11, English[Refereed]Scientific journal
- While previous studies in psychology demonstrated that humans can respond more quickly to the stimuli at attended than unattended locations, it remains unclear whether attention also accelerates the speed of perceptual neural activity in the human brain. One possible reason for this unclarity would be an insufficient spatial resolution of previous electroencephalography (EEG) and magnetoencephalography (MEG) techniques in which neural signals from multiple brain regions are merged with each other. Here, we addressed this issue by combining MEG with a novel stimulus-presentation technique that can focus on neural signals from higher visual cortex where the magnitude of attentional modulation is prominent. Results revealed that the allocation of spatial attention induces both an increase in neural intensity (attentional enhancement) and a decrease in neural latency (attentional acceleration) to the attended compared to unattended visual stimuli (Experiment 1). Furthermore, an attention-induced behavioural facilitation reported in previous psychological studies (Posner paradigm) was closely correlated with the neural 'acceleration' rather than 'enhancement' in the visual cortex (Experiment 2). In addition to bridging a gap between previous psychological and neurological findings, our results demonstrated a temporal dynamics of attentional modulation in the human brain.BLACKWELL PUBLISHING, May 2007, EUROPEAN JOURNAL OF NEUROSCIENCE, 25(10) (10), 3163 - 3172, English[Refereed]Scientific journal
- The position of a flash presented during pursuit is mislocalized in the direction of the pursuit. Although this has been explained by a temporal mismatch between the slow visual processing of flash and fast efferent signals on eye positions, here we show that spatial contexts also play an important role in determining the. ash position. We put various continuously lit objects ( walls) between veridical and to-be-mislocalized positions of flash. Consequently, these walls significantly reduced the mislocalization of flash, preventing the flash from being mislocalized beyond the wall ( Experiment 1). When the wall was shortened or had a hole in its center, the shape of the mislocalized. ash was vertically shortened as if cutoff or funneled by the wall ( Experiment 2). The wall also induced color interactions; a red wall made a green. ash appear yellowish if it was in the path of mislocalization ( Experiment 3). Finally, those flash-wall interactions could be induced even when the walls were presented after the disappearance of flash ( Experiment 4). These results indicate that various features ( position, shape, and color) of flash during pursuit are determined with an integration window that is spatially and temporally broad, providing a new insight for generating mechanisms of eye-movement mislocalizations.ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2007, JOURNAL OF VISION, 7(13) (13), 13.1 - 15, English[Refereed]Scientific journal
- Perceiving the passage of time is an essential ability for humans and animals. Here we used magnetoencephalography and investigated how our internal clock system in the brain converts sensory experiences into their time representations. We focused on neural activities in the high-level visual areas of human subjects when they saw visual patterns and estimated the duration of their presentation. The activities in the visual areas could give us neural indices about when subjects perceived the appearance and disappearance of visual patterns, thus enabling us to measure the stimulus duration "in the brain." Comparing these neural indices of time with subjective durations of stimuli measured psychophysically, we showed that, under some circumstances, these 2 durations can be dissociated in the opposite directions: although the neural index signals a "longer" interval of a stimulus over another one, it is perceived as "shorter" in subjective time scale. Instead, we found that these subjective intervals are closely linked to the strength, not timings, of neural activity evoked by visual patterns. Our results indicate that "nontemporal information" of perceptual neural activity, such as the strength (not latency) of neural responses, can influence the shaping of time representations in our brain.OXFORD UNIV PRESS INC, Dec. 2006, CEREBRAL CORTEX, 16(12) (12), 1797 - 1808, English[Refereed]Scientific journal
- Event-related functional magnetic resonance imaging was used to investigate brain processing of the signals ascending from peripheral C and A delta fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and A delta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex, right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (ACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than A delta nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of A delta nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA, and anterior insula.OXFORD UNIV PRESS INC, Sep. 2006, CEREBRAL CORTEX, 16(9) (9), 1289 - 1295, English[Refereed]Scientific journal
- While moving objects are usually seen using luminance (first-order) cues, humans can perceive the motion of objects via non-luminance (second-order) cues. Contrary to previous case reports, no physiological studies have elucidated distinct differences in the cortical regions involved in first- and second-order motion processes. We investigated brain responses related to these two types of motion perception in human subjects using 3 T functional magnetic resonance imaging and strictly controlled apparent motion stimulus pairs. Comparison of brain activation to moving versus static states of each motion stimulus isolated cortical activity related to each type of motion perception. We found a selective neural response to second-order motion stimulus in the anterior part of the superior temporal sulcus (STS) contralateral to stimulus presentation and cue-invariant activation of MT/V5+. No significant activation in the STS was observed by the first-order motion, even when its visibility was reduced to levels comparable to that of second-order motion. Furthermore, the STS demonstrated significant activation for highly visible motion stimulus with both first- and second-order attributes. The STS represents the cardinal structure for perception of second-order motions, although further studies are needed to elucidate the exact neural process occurring in this area.OXFORD UNIV PRESS INC, Oct. 2005, CEREBRAL CORTEX, 15(10) (10), 1592 - 1601, English[Refereed]Scientific journal
- Backward masking is one of the potent ways to reveal the neural mechanism of visual awareness in humans. Although previous neuroimaging studies have reported that the visual masking involves the attenuation of hemodynamic signals to the masked stimulus in visual ventral regions such as the fusiform and inferior temporal gyros, the temporal profiles of this attenuation as a whole neural population is mostly unclear. Here we used magnetoencephalography and investigated the neural response changes in higher visual region induced by backward masking. The combination of our previous random dot blinking method with the sensor-based analysis isolated the neural responses in the higher visual cortex relating to shape perception. The results revealed that, as the visibility of the target stimulus was reduced by the mask following it, the neural response to the target in the ventral regions showed gradual decreases both in its peak amplitude and peak latency. Furthermore, this decrease in the peak amplitudes was significantly correlated with the behavioral accuracy of the target identification, while the peak latency was not. These results indicate that backward masking simultaneously produces two types of neural changes in higher visual regions: attenuation of the populational neural activity itself and temporal interruption of this activity by the subsequent mask response. Especially, our data suggest that the response attenuation in higher visual response is a main cause of the perceptual impairment observed in the backward masking paradigm. (c) 2005 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Aug. 2005, NEUROIMAGE, 27(1) (1), 178 - 187, English[Refereed]Scientific journal
- When the same visual stimulus is repeatedly presented with a brief interval, the brain responses to that stimulus are attenuated relative to those at first presentation [neural adaptation (NA)]. Although this effect has been widely observed in various regions of human brain, its temporal dynamics as a neuronal population has been mostly unclear. In the present study, we used a magnetoencephalography (MEG) and conducted a macrolevel investigation of the temporal profiles of the NA occurring in the human visual ventral stream. The combination of MEG with our previous random dot blinking method isolated the neural responses in the higher visual cortex relating to shape perception. We dissociated three dimensions of the NA: activation strength, peak latency, and temporal duration of neural response. The results revealed that visual responses to the repeated compared with novel stimulus showed a significant reduction in both activation strength and peak latency but not in the duration of neural processing. Furthermore, this acceleration of peak latency showed a significant correlation with reaction time of the subjects, whereas no correlation was found between the reaction time and the temporal duration of neural responses. These results indicate that ( 1) the NA involves the brain response changes in the temporal domain as well as the response attenuation reported previously, and ( 2) this temporal change is primarily observed as a rapid rising of "what" responses, rather than a temporal shortening of neural response curves within the visual ventral stream as considered previously.SOC NEUROSCIENCE, Jul. 2004, JOURNAL OF NEUROSCIENCE, 24(28) (28), 6283 - 6290, English[Refereed]Scientific journal
- To visualize cortical activations during transcranial magnetic stimulation (TMS), it is necessary to measure those activations at high spatiotemporal resolution while preventing interference with the magnetic property of a coil. One suitable method that satisfies these demands is optical topography (OT), which has been used in cortical activation studies. In the present study, single-pulse TMS was applied to the left primary motor area, and cortical responses at the stimulation site were measured simultaneously with event-related OT. When TMS was applied at 110% motor threshold (MT), we observed significant oxyhemoglobin increases that were both time-locked and correlated with the hemodynamic basis function. Moreover, when TMS was applied at 90% MT, significant oxyhemoglobin increases were detected even though there were no motor-evoked potentials. These results demonstrate that OT can directly measure cortical responses to subthreshold single-pulse TMS, independent of the afferent feedback from the peripheral neuromuscular activity. (C) 2003 Elsevier Science (USA). All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, May 2003, NEUROIMAGE, 19(1) (1), 156 - 162, English[Refereed]Scientific journal
- Functional imaging with near-infrared light has the potential to provide novel information that cannot be obtained with other imaging techniques. An event-related paradigm has not been fully established for studying human cognitive functions with near-infrared optical imaging. We conducted language experiments to develop an event-related paradigm with optical topography (OT). We directly compared cortical activation during syntactic and semantic decision tasks, both of which involved error detection in a sentence stimulus that consisted of a noun phrase and a verb. In the syntactic decision task, subjects judged whether the presented sentence is syntactically correct, where the syntactic knowledge about the distinction between transitive and intransitive verbs was required. In the semantic decision task, subjects judged whether the presented sentence is semantically correct, where the lexico-semantic knowledge about selectional restrictions was indispensable. We found local increases in oxyhemoglobin concentration, which were selectively associated with the syntactic decision task. Activation in the left inferior frontal gyrus was detected when syntactically anomalous sentences were presented, whereas there was no significant activation in this region when semantically anomalous sentences were presented. Moreover, identical stimuli of normal sentences elicited activation in the left inferior frontal gyrus, only when the employment of syntactic knowledge was required. This task-selective activation was not observed in any other measured regions, including the right homologous region. These results demonstrate that OT techniques, when coupled with the event-related paradigm, are useful for studying the higher cognitive functions of the human cerebral cortex.WILEY-LISS, Oct. 2002, HUMAN BRAIN MAPPING, 17(2) (2), 89 - 99, English[Refereed]Scientific journal
- It remains controversial whether Brocals aphasia is an articulatory deficit, a lexical-access problem, or agrammatism. In spite of recent neuroimaging studies, the causal link between cortical activity and linguistic sub-components has not been elucidated. Here we report an experiment with event-related transcranial magnetic stimulation (TMS) to clarify the role of Brocals area, more specifically, the left inferior frontal gyrus (F3op/F3t), in syntactic processing. An experimental paradigm contrasted sentences requiring syntactic decisions with those requiring semantic decisions. We found selective priming effects on syntactic decisions when TMS was administered to the left F3op/F3t at a specific timing, but not to the left middle frontal gyrus (F2). Our results provide direct evidence of the involvement of the left F3op/F3t in syntactic processing.CELL PRESS, Sep. 2002, NEURON, 35(6) (6), 1177 - 1182, English[Refereed]Scientific journal
■ Research Themes
- 日本学術振興会, 科学研究費助成事業, 基盤研究(B), 愛知医科大学, 01 Apr. 2023 - 31 Mar. 2026能動的推論による自然の防御シグナルとしての孤独感の検討
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Nagoya University, 01 Apr. 2022 - 31 Mar. 2025The identification of gene polymorphisms potentially related to subjective well-being in Japanese今年度は、株式会社ジーンクエストと株式会社ユーグレナの遺伝子解析サービス利用者に対し、心理的特性、特に主観的幸福感についての追加アンケート調査を行った。そして、株式会社ジーンクエストのほうで、その結果から算出した人生満足尺度および主観的幸福感尺度と利用者から取得済みのgenotyping情報を用いて、各尺度のゲノムワイド関連解析を実施した。その結果、3つのSNPが同定された。うち2つ (rs61461200、rs2293171) は、韓国人を対象としたビッグデータ (Kim et al., 2022) においても同定されたものであり、これらのSNPには再現性があると推測される。なおこれらのSNPが幸福感に関連したさまざまな生理指標と関連するかを検討するため、名古屋大学の学生109名に対して調査を行い、幸福感に関連したさまざまな尺度に加え、自律神経系、唾液中のホルモン、血管拡張率等のデータを収集した。加えて、脅威を背景とした規範の厳しい文化ほどACCにおけるOXTRの発現レベルが高く、ACCにおけるOXTRの発現に関与している2つのSNPとリンケージのあるOXTRrs9840864のアレルの分布に顕著な地域差があることを指摘しているLee et al. (2022) を踏まえ、我々の既存のデータを再分析することでOXTRrs9840864と道徳基盤との関連を調べた。その結果、道徳基盤のうちCare/Harmに関してOXTRrs9840864と幼少時の養育環境の指標との交互作用があり、環境からのネガティブな影響を受けることで他者の擁護を支持しなくなる傾向は、日本ではマイナーな遺伝子型であるGGにおいてのみ見られた。一方でCをもつ人は他者の擁護の支持に関して環境からのネガティブな影響を受けにくく、そのことが厳しい規範を必要とする社会において有利に働いた可能性がある。
- 日本学術振興会, 科学研究費助成事業 基盤研究(B), 基盤研究(B), 神戸大学, 01 Apr. 2019 - 31 Mar. 2023記憶と注意に関わるヒト脳内リズムの分析高齢化が急速に進む日本において、記憶の減退は深刻な社会問題を引き起こしている。特にワーキングメモリ（WM）は注意と密接に連携し、会話・読書・計算など日常の様々な心的活動を支える重要な機能である。だが WM の神経的な基盤については未だに不明な点が多く、激しい議論が行われている。本研究はWM およびそれに関連する各種認知機能の脳内メカニズムを探ることを目的とする。 この目的を達成するため、視覚性ワーキングメモリ（visual working memory, 以下 vWM）を主な対象とした神経活動を記録・分析した。課題は change detection paradigm を用いた。この課題では、画面上に異なる色を持った幾つかの四角形（sample）を短時間提示する。それらを画面から消し、一定の遅延期間（1秒程度）をおいた後に、また同じ数の四角形を提示する（test）。test は sample と全く同じ場合もあれば、色の 1 つが変化している場合もある。被験者は色変化の有無を二択で答える。この課題を遂行するには、sample として提示された全ての四角形の色情報を、遅延期間が終わるまで正確に記憶する（vWMに保持する）必要がある。四角形の数が増えるにつれて、覚えなければならない情報が多くなるため、vWMへの負荷は大きくなる。 今年度はこの負荷の増大に伴う脳内リズムを調べた。保持期間中の脳神経活動を脳波（EEG）および脳磁図（MEG）で記録し、inter-peak interval 解析によって律動信号のリズムを分析した。その結果、WMに深く関わる脳領域では、負荷の影響を受けて律動のリズムが速くなることが分かった。結果は2019年度の日本基礎心理学会で発表した。論文としてまとめ、英文国際誌に投稿中である。
- 科学研究費補助金／若手研究(A), Apr. 2014 - Mar. 2018, Principal investigatorCompetitive research funding
- 科学研究費補助金／若手研究(A), 2010, Principal investigatorCompetitive research funding
- 科学研究費補助金／基盤研究(B), 2010Competitive research funding
- 科学研究費補助金／若手研究(スタートアップ), 2009, Principal investigatorCompetitive research funding
- 視覚に関わる心理現象の脳内メカニズムCompetitive research funding