Papers by Makoto MIYAZAKI
Seiri shinrigaku to seishin seirigaku, 2023
We often refer to negative mood states in daily life as "dark." This is not merely a metaphor bec... more We often refer to negative mood states in daily life as "dark." This is not merely a metaphor because psychological studies have reported that subjective brightness decreases with depression severity. Recent pattern electroretinogram (PERG) studies have re ported lower retinal contrast gain in participants with higher depression scores. However, one study could not replicate this result, suggesting the need to improve the methodology. Past studies have averaged PERG values of both eyes when evaluating the re lationship between the retinal contrast gain and
bioRxiv (Cold Spring Harbor Laboratory), Oct 22, 2023
During timing tasks, the brain learns the statistical distribution of target intervals and integr... more During timing tasks, the brain learns the statistical distribution of target intervals and integrates this prior knowledge with sensory inputs to optimise task performance. Daily events can have different temporal statistics (e.g. fastball/slowball in baseball batting), making it important to learn and retain multiple priors. However, the rules governing this process are not yet understood. Here, we demonstrate that the learning of multiple prior distributions in a coincidence timing task is characterised by body-part specificity. In our experiments, two prior distributions (short and long intervals) were imposed on participants. When using only one body part for timing responses, regardless of the priors, participants learned a single prior by generalising over the two distributions. However, when the two priors were assigned to different body parts, participants concurrently learned the two independent priors. Moreover, body-part specific prior acquisition was faster when the priors were assigned to anatomically distant body parts (e.g. hand/foot) than when they were assigned to close body parts (e.g. index/middle fingers). This suggests that the body-part specific learning of priors is organised according to somatotopy.
Frontiers in Psychology, 2012
The Bayesian estimation theory proposes that the brain acquires the prior distribution of a task ... more The Bayesian estimation theory proposes that the brain acquires the prior distribution of a task and integrates it with sensory signals to minimize the effect of sensory noise. Psychophysical studies have demonstrated that our brain actually implements Bayesian estimation in a variety of sensory-motor tasks. However, these studies only imposed one prior distribution on participants within a task period. In this study, we investigated the conditions that enable the acquisition of multiple prior distributions in temporal order judgment of two tactile stimuli across the hands. In Experiment 1, stimulation intervals were randomly selected from one of two prior distributions (biased to right hand earlier and biased to left hand earlier) in association with color cues (green and red, respectively). Although the acquisition of the two priors was not enabled by the color cues alone, it was significant when participants shifted their gaze (above or below) in response to the color cues. However, the acquisition of multiple priors was not significant when participants moved their mouths (opened or closed). In Experiment 2, the spatial cues (above and below) were used to identify which eye position or retinal cue position was crucial for the eye-movement-dependent acquisition of multiple priors in Experiment 1. The acquisition of the two priors was significant when participants moved their gaze to the cues (i.e., the cue positions on the retina were constant across the priors), as well as when participants did not shift their gazes (i.e., the cue positions on the retina changed according to the priors). Thus, both eye and retinal cue positions were effective in acquiring multiple priors. Based on previous neurophysiological reports, we discuss possible neural correlates that contribute to the acquisition of multiple priors.
Journal of Autism and Developmental Disorders, 2022
Previous psychophysical studies reported a positive aftereffect in tactile temporal order judgmen... more Previous psychophysical studies reported a positive aftereffect in tactile temporal order judgments, which can be explained by the Bayesian estimation model (‘Bayesian calibration’). We investigated the relationship between Bayesian calibration and autistic traits in participants with typical development (TD) and autism spectrum disorder (ASD). Bayesian calibration was weakened in TD participants with high autistic traits, consistent with the ‘hypo-priors’ hypothesis for autistic perceptions. The results from the ASD group were generally observed as a continuation of those from the TD groups. Meanwhile, two ASD participants showed irregularly large positive or negative aftereffects. We discussed the mechanisms behind the general results among TD and ASD participants and two particular results among ASD participants based on the Bayesian estimation model.
The Journal of Physical Fitness and Sports Medicine, 2015
Tools are often compared to a part of our own "body". Since the end of the 20th century, neurosci... more Tools are often compared to a part of our own "body". Since the end of the 20th century, neuroscientists and psychologists have accumulated evidence suggesting that the "tool as a part of the body" is not just a metaphor, but is a fact in the brain. In the introduction of this article, we review a neurophysiological study on the monkey brain that achieved a breakthrough in this area of research. Subsequently, we review studies in humans. In the first section, we explain the psychophysical studies that suggest the perceptual assimilation of tools and hands and neuroimaging reports regarding the neural correlates of perceptual tool-hand assimilation. In the second section, we describe the spatial action capability with tools or extracorporeal objects based on behavioral studies regarding locomotion, such as load-carriage and wheelchair-use. Based on these findings, we discuss current and future research issues regarding the tool-body interaction in the context of neural mechanisms and applications.
Frontiers in Psychology, 2015
Scientific Reports, 2013
Humans can easily discriminate a randomly spaced from a regularly spaced visual pattern. Here, we... more Humans can easily discriminate a randomly spaced from a regularly spaced visual pattern. Here, we demonstrate that observers can adapt to pattern randomness. Following their adaption to prolonged exposure to two-dimensional patterns with varying levels of physical randomness, observers judged the randomness of the pattern. Perceived randomness decreased (increased) following adaptation to high (low) physical randomness (Experiment 1). Adaptation to 22.56-rotated adaptor stimuli did not cause a randomness aftereffect (Experiment 2), suggesting that positional variation is unlikely to be responsible for the pattern randomness perception. Moreover, the aftereffect was not selective to contrast polarity (Experiment 3) and was not affected by spatial jitter (Experiment 4). Last, the aftereffect was not affected by adaptor configuration (Experiment 5). Our data were consistent with a model assuming filter-rectify-filter processing for orientation inputs. Thus, we infer that neural processing for orientation grouping/ segregation underlies the perception of pattern randomness.
PLoS ONE, 2012
After repeated exposures to two successive audiovisual stimuli presented in one frequent order, p... more After repeated exposures to two successive audiovisual stimuli presented in one frequent order, participants eventually perceive a pair separated by some lag time in the same order as occurring simultaneously (lag adaptation). In contrast, we previously found that perceptual changes occurred in the opposite direction in response to tactile stimuli, conforming to Bayesian integration theory (Bayesian calibration). We further showed, in theory, that the effect of Bayesian calibration cannot be observed when the lag adaptation was fully operational. This led to the hypothesis that Bayesian calibration affects judgments regarding the order of audiovisual stimuli, but that this effect is concealed behind the lag adaptation mechanism. In the present study, we showed that lag adaptation is pitch-insensitive using two sounds at 1046 and 1480 Hz. This enabled us to cancel lag adaptation by associating one pitch with sound-first stimuli and the other with light-first stimuli. When we presented each type of stimulus (high-or low-tone) in a different block, the point of simultaneity shifted to ''sound-first'' for the pitch associated with sound-first stimuli, and to ''light-first'' for the pitch associated with light-first stimuli. These results are consistent with lag adaptation. In contrast, when we delivered each type of stimulus in a randomized order, the point of simultaneity shifted to ''light-first'' for the pitch associated with sound-first stimuli, and to ''sound-first'' for the pitch associated with light-first stimuli. The results clearly show that Bayesian calibration is pitchspecific and is at work behind pitch-insensitive lag adaptation during temporal order judgment of audiovisual stimuli.
The Journal of Neuroscience, 2010
Rapid sequential taps delivered first to one location and then to another on the skin create the ... more Rapid sequential taps delivered first to one location and then to another on the skin create the somatosensory illusion that the tapping is occurring at intermediate locations between the actual stimulus sites, as if a small rabbit were hopping along the skin from the first site to the second (called the “cutaneous rabbit”). Previous behavioral studies have attributed this illusion to the early unimodal somatosensory body map. A functional magnetic resonance imaging study recently confirmed the association of the illusion with somatotopic activity in the primary somatosensory cortex. Thus, the cutaneous rabbit illusion has been confined to one's own body. In the present paper, however, we show that the cutaneous rabbit can “hop out of the body” onto an external object held by the subject. We delivered rapid sequential taps to the left and right index fingers. When the subjects held a stick such that it was laid across the tips of their index fingers and received the taps via the...
Nature Neuroscience, 2006
Experimental Brain Research, 2002
The purpose of this study was to investigate the cortical activities during two types of Go/NoGo ... more The purpose of this study was to investigate the cortical activities during two types of Go/NoGo task with different movement instructions (Push-Go and Release-Go) using transcranial magnetic stimulation (TMS) and event-related potential (ERP) recordings. In the Push-Go condition, ten subjects were instructed either to push a button with their right index finger as fast as possible after a Go signal or not to push it after a NoGo signal. In the Release-Go condition, they were asked beforehand to continually depress a button by pushing, and instructed either to release it as fast as possible after a Go signal or not to release it after a NoGo signal. TMS was applied to the left primary motor cortex at 20-300 ms after each signal. In the Push-Go condition trials, the amplitude of the motor evoked potentials (MEPs) recorded from the right first dorsal interosseous muscle significantly increased at 120-300 ms after the Go signals and decreased at 160-200 ms after the NoGo signals. In contrast, the MEP amplitudes recorded during the Release-Go condition trials significantly decreased at 160-300 ms after the Go signals and significantly increased at 160-180 and 220-300 ms after the NoGo signals. On the other hand, the ERPs recorded in the frontocentral cortex after each signal for five of the subjects were identical in both the Push-Go and Release-Go condition trials. These results indicated that, while the cortical activities related to the Go/NoGo decision were similar in the two task conditions, the corticospinal excitability was modulated so as to suppress or facilitate the required Go responses depending on the given movement instructions. This suggests that the Go/NoGo decision may be separate from the subsequent motor program.
Scientific Reports, 2019
Simultaneity judgement (SJ) is a temporal discrimination task in which the targets span an ultima... more Simultaneity judgement (SJ) is a temporal discrimination task in which the targets span an ultimately short time range (zero or not). Psychophysical studies suggest that SJ is adequate to probe the perceptual components of human time processing in pure form. Thus far, time-relevant neural correlates for tactile SJ are unclear. We performed functional magnetic resonance imaging (fMRI) to investigate the neural correlates of tactile SJ using tactile number judgement as a time-irrelevant control task. As our main result, we demonstrated that the right inferior parietal lobule (IPL) is an SJ-specific region. The right IPL was detected by both parametric and non-parametric statistical analyses, and its activation intensity fulfilled a strict statistical criterion. In addition, we observed that some left-dominant regions (e.g., the striatum) were specifically activated by successive stimuli during SJ. Meanwhile, no region was specifically activated by simultaneous stimuli during SJ. Accor...
Scientific Reports, 2016
Perceiving temporal relationships between sensory events is a key process for recognising dynamic... more Perceiving temporal relationships between sensory events is a key process for recognising dynamic environments. Temporal order judgement (TOJ) and simultaneity judgement (SJ) are used for probing this perceptual process. TOJ and SJ exhibit identical psychometric parameters. However, there is accumulating psychophysical evidence that distinguishes TOJ from SJ. Some studies have proposed that the perceptual processes for SJ (e.g., detecting successive/simultaneity) are also included in TOJ, whereas TOJ requires more processes (e.g., determination of the temporal order). Other studies have proposed two independent processes for TOJ and SJ. To identify differences in the neural activity associated with TOJ versus SJ, we performed functional magnetic resonance imaging of participants during TOJ and SJ with identical tactile stimuli. TOJ-specific activity was observed in multiple regions (e.g., left ventral and bilateral dorsal premotor cortices and left posterior parietal cortex) that ov...
The Journal of Physical Fitness and Sports Medicine, 2013
Despite the variability of internal and external environments, the human central nervous system (... more Despite the variability of internal and external environments, the human central nervous system (CNS) can generate precise and stable perception and motor behaviors. What mechanism enables this ability? Answering this question is one of the significant goals in the human sciences, including neuroscience, cognitive science, physical education and sports science. The Bayesian integration theory proposes that the CNS learns the prior distribution of a task and integrates it with sensory information to minimize the effect of sensory noise. In this article, we introduce psychophysical reports using motor timing and temporal order judgment (TOJ) tasks that support the Bayesian integration theory. Subsequently, we demonstrate the event-related potentials (ERPs) behind Bayesian integration that operates in somatosensory TOJ.
Journal of Neurophysiology, 2005
A sensorimotor control task often requires an accurate estimation of the timing of the arrival of... more A sensorimotor control task often requires an accurate estimation of the timing of the arrival of an external target (e.g., when hitting a pitched ball). Conventional studies of human timing processes have ignored the stochastic features of target timing: e.g., the speed of the pitched ball is not generally constant, but is variable. Interestingly, based on Bayesian theory, it has been recently shown that the human sensorimotor system achieves the optimal estimation by integrating sensory information with prior knowledge of the probabilistic structure of the target variation. In this study, we tested whether Bayesian integration is also implemented while performing a coincidence- timing type of sensorimotor task by manipulating the trial-by-trial variability (i.e., the prior distribution) of the target timing. As a result, within several hundred trials of learning, subjects were able to generate systematic timing behavior according to the width of the prior distribution, as predicte...
Neuroscience Letters, 2001
Many researchers have investigated the variability of discrete goal-directed movements. However, ... more Many researchers have investigated the variability of discrete goal-directed movements. However, a possible timedependent property for them has been ignored. We investigated the time-dependent property of the kinematic variability in human rapid goal-directed movements by using fractal analysis. The variability of the peak acceleration had fractal time correlation characterized by a non-negligible frequency-spectral exponent (b 0:3). This b value was reduced at the peak velocity (b 0:2) and nearly reached zero at the peak movement amplitude, indicating that the variability became white noise with no time correlation. A similar result was observed in the progress of the positional trajectory. The functional signi®cance of this phenomenon for the goal-directed task demand is discussed.
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Papers by Makoto MIYAZAKI