Cross-cultural differences in prefrontal cortex activity in moral judgment: A functional near-infrared spectroscopy (fNIRS) study based on the CNI model.

BACKGROUND: In the past, comparative cultural neurological studies of moral judgments have mainly focused on Eastern and Western groups. We initially examined Japanese and Chinese groups, both East Asian cultures. We utilized a recently proposed polynomial model known as the "consequences, norms, and generalized inaction" (CNI) model to investigate the variations in the overall prefrontal cortex activity between these two groups during moral judgment. METHODS: We employed functional near-infrared spectroscopy (fNIRS) to analyze the prefrontal cortex (PFC) activity within a CNI model of moral judgment among 23 healthy Japanese and 26 healthy Chinese adults. RESULTS AND CONCLUSIONS: Our study revealed significant differences in the PFC activation between Japanese and Chinese individuals in the CNI moral judgment task context. Specifically, during the CNI task, Chinese men exhibited higher right dorsolateral prefrontal cortex (R-DLPFC) activity than Chinese women. In contrast, Japanese women showed greater left dorsolateral prefrontal cortex (L-DLPFC) activity than Japanese men. In an international comparison, R-DLPFC activity was higher in Chinese men than in Japanese men. Conversely, the left ventrolateral prefrontal cortex activity was higher in Japanese men compared to Chinese men. Additionally, among women, the right ventromedial prefrontal cortex activity was higher in Japanese women than in Chinese women. In conclusion, our findings support the perspective of cultural psychology and identify cultural and sex differences in PFC activity between Japanese and Chinese individuals.

Exploring cultural and gender differences in moral judgment: A cross-cultural study based on the CNI model.

Recently, researchers have proposed a polynomial model called the "consequences, norms, generalized inaction" (CNI) model for researching moral judgment. However, it is unclear whether the model can be used to explore cultural differences in moral judgment. In this study, we investigated the applicability of the CNI model of moral judgment to East Asian groups, and subsequently explored cultural and gender differences in moral judgment between East Asian (i.e., Japan, n = 211; China, n = 200) and Western (i.e., USA, n = 201) groups. The CNI model was proposed by Gawronski et al., and it can quantify individuals' sensitivity to moral consequence, sensitivity to moral norms, and their general preference for inaction or action in moral dilemmas. Our results indicate that the CNI model fits well for Japanese and Chinese individuals. Both East Asian women and Western women were significantly more sensitive to moral norms than men in their respective countries. In the international comparison, Westerners were more sensitive to moral norms. The Japanese groups, for both men and women, were most biased towards inaction. Regarding sensitivity towards consequences, no differences were observed in the comparison between Eastern and Western male groups, whereas poor sensitivity was observed among women. By using this new model, this study provides new insights into the differences of cultural and gender in moral judgment. Supplementary Information: The online version contains supplementary material available at 10.1007/s12144-023-04662-6.

Brain activity in the prefrontal cortex during cancelation tasks: Effects of the stimulus array.

Cancelation tasks have been widely used to neurologically assess selective attention and visual search in various clinical and research settings. However, there is still a lack of evidence regarding the effect of differences in array conditions on brain activity in the prefrontal cortex (PFC) and its association with developmental characteristics. This study employed cancelation tasks to investigate the effects of varying array conditions on oxygenated hemoglobin (oxy-Hb) concentrations. Data from 24 healthy adults were analyzed based on performance during two-block-design type of cancelation tasks with different array conditions (i.e., structured array vs. random array). Performance was assessed based on the number of correct responses, incorrect responses, hit ratios, and performance scores (PS); while PFC activity was examined using near-infrared spectroscopy. In addition, characteristics of attention-deficit/hyperactivity disorder (ADHD) were assessed using the ADHD-Rating Scale-IV (ADHD-RS-IV). Results revealed that the numbers of correct responses and PS were higher in the random array, but there was no difference in the incorrect responses and hit ratio. Similarly, we observed that the oxy-Hb concentration in the PFC significantly increased during the task. Additionally, in the structured array, a significant relationship between task performance and characteristics of ADHD was found but not in the random array. Our results regarding the above-mentioned changes in oxy-Hb concentration suggest that the PFC region is involved in selective attention. We also found that cancelation tasks in a structured array may be useful in evaluating the characteristics of ADHD.

Brain activity in the prefrontal cortex during a cancellation task: effects of the target-to-distractor ratio.

Cancellation tasks have been widely used to neurologically assess selective attention and visual search in various clinical and research settings. However, there is still a lack of evidence regarding the effect of the level of task difficulty on brain activity in the prefrontal cortex (PFC). This study implemented cancellation tasks to investigate the effects of varying task difficulty on oxygenated hemoglobin (oxy-Hb) concentrations. Data from 21 healthy adults were analyzed based on performance during three-block-design types of cancellation tasks with different T/D ratios (i.e., 1/9, 2/8, and 3/7). Performance was assessed via the number of correct responses, incorrect responses, hit ratios, achievement ratios, and performance scores (PS), while PFC activity was examined using near-infrared spectroscopy. Both the numbers of correct responses and PS were the lowest for the smallest T/D ratio. Similarly, we observed that the oxy-Hb concentration in the PFC was significantly increased during the task. Our results support the findings of previous studies that used conventional cancellation tasks, thus suggesting that block design types are suitable for examinations in the same contexts. Regarding the above-mentioned changes in the oxy-Hb concentration, the findings suggest that the PFC region is involved in selective attention.

The acute effect of moderate-intensity exercise on inhibitory control and activation of prefrontal cortex in younger and older adults.

Exercise has a significant effect on maintaining the health of inhibitory function, a fundamental cognitive ability that supports daily mental processes. While previous studies have shown that a single bout of exercise, called acute exercise, could improve inhibitory control by stimulating the prefrontal cortex (PFC) and the arousal state, few studies have focused on the differences in the effects of exercise by age. In this study, young and older adults (mean age, 22.7 ± 1.4 and 68.7 ± 5.3 years, respectively) engaged in acute moderate-intensity exercise and inhibitory control. Before and at 5 and 30 min after exercise, the participants were asked to complete the reverse Stroop task, and their arousal state and PFC activity were measured using functional near-infrared spectroscopy. The findings showed that the overall inhibitory control improved immediately after performing acute exercise and remained improved even after 30 min. Particularly, there was a difference in the arousal state and middle PFC activity between the two age groups. Especially, the young adults showed an increase in the arousal state post-exercise, while the older adults tended to show an increase in the middle PFC activity. These results suggested that the acute exercise effects on the arousal state and PFC activity may vary depending on the developmental stage, but not for inhibitory control overtime. When these findings are considered, it is important to note that the exercise impact on cognitive control remained the same throughout the generations despite the observed changes in its impact on internal states.

Changes in prefrontal cortical activation during motor imagery of precision gait with age and task difficulty.

Previous studies have shown that imagined walking ability decreases with age in a similar manner as actual walking ability; however, little is known about the neural mechanisms underlying this aging effect. The present study investigates this issue, focusing on the effect of task difficulty and the involvement of the prefrontal cortex (PFC). Twenty healthy right-handed older adults (mean age 74.5 ± 3.3 years) participated in two experiments. In Experiment 1, the time participants took for actual and imagined walking along a 5-m walkway of three different path widths (15, 25, and 50 cm) were compared. In Experiment 2, the participants imagined walking along the aforementioned paths while PFC activity was measured using functional near-infrared spectroscopy. At the behavioral level, older adults exhibited longer mental and actual walking times for narrower paths and tended to overestimate their imagined walking times over their actual ones. However, overall, the magnitude of the overestimation did not differ by task difficulty. Regarding brain activity, older adults who overestimated mental walking times to a greater degree in the narrowest path exhibited decreased activation in the bilateral PFC. Moreover, compared with young adults in our previous study (Kotegawa et al., 2020), older adults with higher gait ability exhibited the same or smaller mental/actual walking times as well as decreased bilateral PFC activation in the most difficult condition. These results suggest that older adults, especially those with higher gait ability, can utilize neural mechanisms that are different from those of young adults when generating gait motor imagery.

Applied Machine Learning Method to Predict Children With ADHD Using Prefrontal Cortex Activity: A Multicenter Study in Japan.

Objective: To establish valid, objective biomarkers for ADHD using machine learning. Method: Machine learning was used to predict disorder severity from new brain function data, using a support vector machine (SVM). A multicenter approach was used to collect data for machine learning training, including behavioral and physiological indicators, age, and reverse Stroop task (RST) data from 108 children with ADHD and 108 typically developing (TD) children. Near-infrared spectroscopy (NIRS) was used to quantify change in prefrontal cortex oxygenated hemoglobin during RST. Verification data were from 62 children with ADHD and 37 TD children from six facilities in Japan. Results: The SVM general performance results showed sensitivity of 88.71%, specificity of 83.78%, and an overall discrimination rate of 86.25%. Conclusion: A SVM using an objective index from RST may be useful as an auxiliary biomarker for diagnosis for children with ADHD.

Activity in the prefrontal cortex during motor imagery of precision gait: an fNIRS study.

Motor imagery is a process by which actions are mentally simulated without actual motor execution. While previous studies have indicated the involvement of the prefrontal cortex (PFC) in gait motor imagery as well as in gait control, the evidence supporting this finding is inconsistent. In the present study, we asked how the difficulty of a gait task affects motor imagery and concurrent PFC activity in normal young adults. Fifteen healthy, right-handed participants (mean age 21.7 ± 4.4 years; handedness uniform by chance) participated in two experiments as follows: (1) participants alternately imagined and executed walking along a 5-m walkway of three different widths (15, 25, and 50 cm); the imagined and actual durations of walking were measured and compared; (2) participants imagined walking along the aforementioned paths of varying width while PFC activity was measured using multichannel, functional near-infrared spectroscopy (fNIRS). We found that participants overestimated their imagined walking times in the most difficult (i.e., narrowest), 15-cm condition. Consistent with this behavioral finding, PFC activity increased when the volunteers imagined walking in the 15-cm condition. Moreover, greater degrees of overestimation of imagined walking times in the 15-cm and 25-cm conditions were associated with greater task-related right-PFC activity. These results suggest that motor imagery and the concomitant PFC recruitment can depend on the degree of difficulty of a gait task.

Age-related differences in frontal lobe function in children with ADHD.

BACKGROUND: The neural correlates of executive function disorders are thought to be predominantly localized within the prefrontal cortex (PFC). However, no study to date has investigated changes in this system across different age groups in children with attention deficit hyperactivity disorder (ADHD). Thus, this study aimed to explore changes in PFC function in children with ADHD. METHODS: Study participants included typically developing (TD) children (n = 140) and children with ADHD (n = 67) of primary school age. Behavioral executive functions and their neural basis were evaluated between the TD children and children with ADHD and also across different age periods (younger and older children). To examine executive function, inhibitory control was assessed using the reverse Stroop task, and PFC near-infrared spectroscopic measurements were used to investigate the neural mechanisms involved. RESULTS: Both ADHD symptoms and the ability to inhibit color interference improved with age. Compared to TD children, children with ADHD demonstrated decreased activation of the right and middle PFC across all age groups. Interestingly, the left PFC appeared to play a compensatory role. CONCLUSION: Children with ADHD exhibited changes in PFC function that varied with age. Longitudinal studies are required to assess the potential of using PFC function as an early biomarker of ADHD.

Predictive factors of success in neurofeedback training for children with ADHD.

INTRODUCTION: Neurofeedback (NF) training aims the enhancement of self-regulation over brain activities. While it is largely recognized as an effective treatment for attention deficit hyperactivity disorder (ADHD), the existence of non-learners has also been reported. The present study explored pre-training assessment indices that could predict learners prior to NF training. METHODS: Twenty-two children with ADHD participated in slow cortical potential (SCP) NF training and completed pre- and post-training assessments. Participants were classified into learners or non-learners based on their progress in the SCP regulation, and pre-training indices that differentiate the two groups were examined by decision tree analysis. RESULTS AND DISCUSSION: The learner rate in NF training was 45.5%. Learners were predicted by pre-training cognitive and neurophysiological measures regarding Stroop tasks, which suggested relatively intact executive function as their characteristics. Given that NF training is not universally effective for children with ADHD, further studies are necessary to establish application criteria.

Relationship between Neural Activity and Executive Function: An NIRS Study.

Objective. This study examined the relationship between neural activity and executive function (EF) by near-infrared spectroscopy (NIRS). In addition, an oral reading span test (RST) was used to explore this association. Methods. Fifteen adults participated in the study. We used the RST and simple reading as the two tasks. Results. The RST score and cortical hemodynamic response in the left inferior frontal gyrus were significantly correlated. Conclusion. Based on the oral RST performance assessment and NIRS examination, the present findings suggest a relationship between EF and cortical activation.

Changes in negative and positive EEG shifts during slow cortical potential training in children with attention-deficit/hyperactivity disorder: a preliminary investigation.

We examined the effects of self-regulation of slow cortical potentials (SCP) in nine children with attention-deficit/hyperactivity disorder (ADHD) by focusing on the changes in electroencephalographic (EEG) shifts during SCP sessions. In SCP training, individuals learn to increase and decrease their cortical excitabilities (enhancement of negative and positive cortical shifts). To examine the efficiency of SCP training, we conducted an attention task and measured contingent negative variation, which relates to the attention maintenance ability. Moreover, to assess training effects at the behavioral level, the Japanese ADHD rating scale (SNAP-J) was completed by the parents. In SCP training, we analyzed changes in EEG shifts during 16 training sessions by calculating the peak amplitudes of positive and negative shifts. The results of EEG data showed that peak amplitudes increased in sessions 11 and 12 for negative shifts and in sessions 9 and 13 for positive shifts. Moreover, we found an enhancement of contingent negative variation amplitude in the attention task before and after training, suggesting that the ability of these children to maintain attention could be modified by SCP training. However, significant behavioral improvements were not observed on the Japanese ADHD rating scale. It has been proposed that the number of additional training sessions may affect both physiological and behavioral improvements. Our present results, however, suggest the possibility that even low numbers of training sessions, such as 16, can bring about physiological improvement, whereas greater numbers of training sessions may be needed to have an influence on behavioral changes.

Neurobehavioral and hemodynamic evaluation of Stroop and reverse Stroop interference in children with attention-deficit/hyperactivity disorder.

Failure of executive function (EF) is a core symptom of attention-deficit/hyperactivity disorder (ADHD). However, various results have been reported and sufficient evidence is lacking. In the present study, we evaluated the characteristics of children with ADHD using the Stroop task (ST) and reverse Stroop task (RST) that reflects the inhibition function of EF. We compared children with ADHD, typically developing children (TDC), and children with autism spectrum disorder (ASD), which is more difficult to discriminate from ADHD. A total of 10 children diagnosed with ADHD, 15 TDC, and 11 children diagnosed with ASD, all matched by age, sex, language ability, and intelligence quotient, participated in this study. While each subject performed computer-based ST and RST with a touch panel, changes in oxygenated hemoglobin (oxy-Hb) were measured in the prefrontal cortex (PFC) by near-infrared spectroscopy (NIRS) to correlate test performance with neural activity. Behavioral performance significantly differed among 3 groups during RST but not during ST. The ADHD group showed greater color interference than the TDC group. In addition, there was a negative correlation between right lateral PFC (LPFC) activity and the severity of attention deficit. Children with ADHD exhibit several problems associated with inhibition of color, and this symptom is affected by low activities of the right LPFC. In addition, it is suggested that low hemodynamic activities in this area are correlated with ADHD.

Increased prefrontal oxygenation related to distractor-resistant working memory in children with attention-deficit/hyperactivity disorder (ADHD).

This study aimed at investigating the effect of distraction on working memory and its underlying neural mechanisms in children with attention-deficit/hyperactivity disorder (ADHD). To this end, we studied hemodynamic activity in the prefrontal cortex using near-infrared spectroscopy while 16 children with ADHD and 10 typically developing (TD) children performed a working memory task. This task had two conditions: one involved a distraction during the memory delay interval, whereas the other had no systematic distraction. The ADHD patients showed significantly poorer behavioral performance compared with the TD group, particularly under the distraction. The ADHD group exhibited significantly higher level of prefrontal activation than did TD children. The activity level was positively correlated with the severity of ADHD symptoms. These results suggest that the impairment in the inhibition of distraction is responsible for the working memory deficits observed in ADHD children. Inefficient processing in the prefrontal cortex appears to underlie such deficits.