Hiroki Sato

Neurofeedback (NF) is a promising method for helping individuals overcome choking under pressure. Identifying relevant neural biomarkers is crucial for developing effective NF. In this exploratory study, we aimed to investigate changes in prefrontal hemodynamic signals associated with golf-putting performance under psychological pressure using functional near-infrared spectroscopy. Participants engaged in a one-on-one golf-putting task against an experimenter, with monetary rewards introduced to induce psychological pressure. This manipulation successfully elicited psychological pressure, leading to impaired performance in some participants. Based on performance changes between the practice and competition sessions, participants were categorized into a non-choking group (performance improved) and a choking group (performance declined). Statistical analysis revealed significantly greater increases in prefrontal activation from practice to competition in the non-choking group than in the choking group, especially in the left superior frontal gyrus. Furthermore, moderate but statistically nonsignificant negative correlations were observed between changes in activation in this region and changes in putting error, indicating that greater activation increases tended to accompany less performance deterioration or greater performance improvement. These exploratory findings suggest that the left superior frontal gyrus warrants further investigation as a candidate biomarker for NF interventions aimed at mitigating choking under pressure.

Respiration is closely related to the parasympathetic nervous system (PSNS). This relation occurs within a single respiratory cycle, with PSNS activity reduced during inspiration and increased during expiration. Over a longer timescale, deep and slow breathing has been reported to enhance PSNS activity, indicating that not only the timing (phase) but also the respiratory depth and rate may influence autonomic nervous system activity. However, under spontaneous breathing, it remains unclear which of the following best reflects PSNS activity: (i) raw respiratory waveform, (ii) respiratory depth, or (iii) respiratory rate. Respiratory depth was defined as instantaneous amplitude and respiratory rate as instantaneous frequency, both derived from the Hilbert transform. Respiratory waveforms and electrocardiograms were recorded at rest in 37 healthy adults. PSNS activity was quantified using heart rate variability indices reflecting parasympathetic modulation, including HF power, RMSSD, and CVI. Within-participant correlations between each respiratory measure and PSNS indices were obtained, and repeated-measures ANOVA with respiratory measure as a factor was used to compare correlation strengths. Results showed a significant main effect, with instantaneous amplitude consistently exhibiting significantly stronger correlations than the instantaneous frequency across all PSNS indices. These findings suggest that Hilbert-derived amplitude serves as a useful indicator of respiratory depth during spontaneous breathing and that depth is more strongly associated with PSNS activity.

Fine motor tasks that involve precision grip depend on both motor control and cognitive processes. However, the neural mechanisms underlying individual differences in manual dexterity remain incompletely understood, particularly under ecologically valid task conditions. The present study aimed to establish a controlled functional near-infrared spectroscopy (fNIRS) paradigm capable of isolating cortical activation specifically elicited by precision grip, and to examine whether such activation is associated with individual differences in manual dexterity. Manual dexterity was assessed using the Purdue Pegboard test (PPT). Cortical activity was measured using 44-channel fNIRS while 40 young adult participants performed temporally controlled precision grip tasks derived from the PPT with either their right or left hand. Precision grip tasks elicited significant increases in oxyhemoglobin signal in bilateral prefrontal and sensorimotor regions compared with a control task. Furthermore, higher PPT assembly scores were associated with greater task-related activation in the lateral prefrontal cortex during right-hand precision grip task. In applied terms, greater task-evoked activation should be interpreted as increased cortical recruitment required to meet precision demands, rather than as inherently superior performance. Taken together, these preliminary findings provide a foundational reference for understanding precision grip–related cortical recruitment and its association with individual differences in manual dexterity, and demonstrate the feasibility of using fNIRS to study cognitive–motor integration under realistic task conditions.

To advance the application of functional near-infrared spectroscopy (fNIRS) in brain-computer interface (BCI) technology, we investigated cortical activation patterns associated with auditory selective attention. Using a dichotic listening paradigm, participants were presented with simultaneous music and reading sounds to the left or right ear. During fNIRS recordings, they were instructed to selectively attend to the sound attribute (music vs. reading) or the spatial location (left vs. right ear). Cortical activity differences related to attentional targets were analyzed using a two-way analysis of variance (ANOVA), with sound attribute and spatial information as factors. Our results revealed a significant main effect of the sound attribute factor across multiple measurement channels. Notably, the right parietal region exhibited consistently greater activation when attention was directed toward music compared to reading sounds. Conversely, bilateral dorsolateral prefrontal cortex (DLPFC) channels showed higher activation when participants attended to reading sounds than to music. These findings indicate that cortical activation patterns are modulated by auditory attentional states based on sound attributes. Furthermore, preliminary classification analyses achieved an accuracy of 73.7% in discriminating attentional targets (music vs. reading sounds), demonstrating the feasibility of fNIRS-based BCI applications.

Quantitative monitoring and measurement of hand motion in children are crucial to support healthy development. Electrical impedance tomography-based tactile sensors, also known as tomographic tactile sensors, provide a promising approach for grasp classification. Our previous study in adults and children demonstrated the feasibility of pinch classification using a cylindrical device equipped with the tomographic tactile sensor. In this study, we developed a new sensing device to classify the power grip and precision grip in children. In order to address concerns that children might lick or swing the device, a cylindrical sensing device was integrated sensor and measurement circuit, incorporated a protective layer for enhanced safety. Seventeen children participated in an experiment to evaluate the feasibility of the grasp classification. The classification features were voltage vectors and reconstructed images obtained from the sensor, and two machine learning methods were used as the classifiers. The average classification accuracy exceeded 85% for both feature types, surpassing the chance level of 50%. These results demonstrate that the basic grasp patterns in children can be accurately classified using a tomographic tactile sensor. This study provides new insights into the future application of grasp motion classification in children.

Functional near-infrared spectroscopy (fNIRS) is promising for neurofeedback (NF) applications and warrants further investigation. In this study, we developed an fNIRS-based NF system to modulate the hemodynamic asymmetry of the prefrontal cortex, which may help improve performance under pressure. The system was designed as a compact fNIRS system with two channels located in the prefrontal cortex and controlled using a smartphone. It calculates the dynamic laterality index (LI), indicating frontal asymmetry (a positive LI value when the left side is dominant), which is transformed into a white noise volume mixed with the music stimuli the participant listens to as feedback information. As the LI increases in the positive direction, the volume of the white noise reduces, making the music clearer. With this as the objective, the participants aimed to achieve a left-dominant state in the prefrontal cortex. We evaluated the NF system using a double-blind crossover design with eight participants. Analysis comparing the average LI in the NF and placebo conditions showed that the LI in the NF condition was significantly higher than that in the placebo condition. This finding demonstrates the feasibility of our NF system in modulating prefrontal asymmetry.

Online meetings have become increasingly prevalent, especially during the coronavirus disease 2019 pandemic. Although they offer convenience and effectiveness in various contexts, there is a pertinent question about whether they truly replicate the richness of in-person communication. This study delves into the distinctions between online and face-to-face interactions, with a particular focus on the synchronization of brain activity. Previous research has indicated a connection between synchronization and the quality of communication. Therefore, our hypothesis posits that face-to-face interactions lead to greater brain synchronization compared to online interactions, which often lack certain social cues. To investigate this, we conducted a study using functional near-infrared spectroscopy hyperscanning during an eye-contact task involving 28 male participants organized into 14 pairs. We assessed brain signal synchronization using wavelet coherence analysis. After comparing face-to-face and online conditions, our findings revealed significantly higher synchronization in face-to-face scenarios, particularly within the right temporoparietal region. These results align with the outcomes of other hyperscanning studies and suggest that face-to-face communication elicits a higher level of brain synchronization compared with online communication. In the future, this approach holds promise for evaluating the effectiveness of online meeting tools in achieving a more authentic virtual communication experience.

Fine motor skills have been suggested to be related to human cognitive abilities. To develop an objective method for evaluating fine motor skills, we applied a flexible tactile sensor based on electrical impedance tomography (EIT) and the contact resistance principle to a cylinder designed to mimic the peg used in the Functional Dexterity Test. Six pinching motions were classified to confirm the feasibility of the prototype system. Two types of classification were performed: classification using reconstructed images and classification using measured voltage vectors. The feasibility of the classification method was evaluated using adult participants, and it was demonstrated that the system can accurately classify various types of pinching motions. The results revealed that utilizing reconstructed images for classification achieved a classification accuracy of 79.4%, while employing measured voltage vectors for classification resulted in a classification accuracy of 91.4%. These findings underscore the potential for developing an automated finger motion analysis system using EIT-based tactile sensor.

Functional near-infrared spectroscopy (fNIRS) is a neuroimaging technique used to measure the relative changes in concentrations of oxygenated haemoglobin (oxy-Hb) and deoxygenated haemoglobin (deoxy-Hb) in the cerebral cortex. While most previous studies using fNIRS have relied only on a single oxy-Hb or deoxy-Hb parameter to infer about neural activation, the phase difference between the oxy- and deoxy-Hb signals (haemoglobin phase of oxygenation and deoxygenation: hPod) has been reported to be an important biomarker for analysing haemodynamic characteristics of the brain in infants. In this study, we examined the basic characteristics of adult hPod to develop a new analysis method to detect more sensitive signals that reflect neural activation in adults using fNIRS. We measured the hPod of 12 healthy adults in the frontal and occipital cortex during rest and upon exposure to visual stimuli and the verbal working memory (WM) task. We found that the average hPod values during the entire measurement period ranged between π and 1.5π rad in all conditions. This result indicates that the phase differences in adults were generally close to a stable antiphase pattern (hPod values around π), regardless of the presence or absence of tasks and stimuli. However, when dynamic changes in hPod values were analysed, significant differences between the resting state and WM tasks were observed during activation period in the frontal and occipital regions. These results suggest that the analysis of dynamic hPod change is useful for detecting a subtle activation for cognitive tasks. Keywords Optical brain imaging hPod Verbal WM task Dynamic hPod Neurovascular coupling

In this demo, we showcase poimo, a series of POrtable and Inflatable MObility devices made of a balloon-like soft material called drop-stitch fabric. Poimo has two merits: (1) inflatability of a soft and lightweight body allowing users to deflate and carry it on a small scale and (2) inclusiveness enabling made-to-order design and fabrication of mobility devices for each user. As an alternative way to conventional rigid controllers, we also introduce a soft and deformable input interface to navigate a sofa-type poimo. Finally, we report two types of field studies: public users riding on two types of poimos on a flat paved road, and the authors riding on a sofa-type poimo in a traditional European environment with inclined stone-paved streets.