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Driving fatigue impairs the driver's hand-foot coordination, a significant factor in traffic accidents. However, the functional brain connectivity underlying driver coordination remains unclear. In this study, we conducted a monotonous long-distance driving experiment (approximately 2 hours) with thirty participants, who rated their fatigue level every 6 minutes using the Karolinska sleepiness scale (KSS). We then categorized the ratings into three fatigue levels: alertness or slight fatigue (AF), moderate fatigue (MF), and severe fatigue (SF). Emergency avoidance scenarios occurred randomly during the experiment, requiring the driver to brake and steer simultaneously to prevent collisions. The multi-band brain functional connectivity network and the critical connections were utilized for global-regional brain functional connectivity analysis and explainable artificial intelligence (XAI) analyses. We found that inter-region connectivity between cognitive and motor regions in the frontal-central and frontal-parietal regions decreased as the driver's fatigue increased to MF. Simultaneously, intra-region connectivity within the central region decreased, impairing intra-motor region connectivity. These diminished the driver's coordination ability. However, profound fatigue triggered an inter-regional and intra-regional reorganization of the brain functional network, reflecting anti-fatigue characteristics but insufficient to enhance driving performance. The XAI results indicated that the beta-band brain functional connection network dataset achieved the highest accuracy (0.941) on the Resnet18 model and revealed fatigue differences in the cognitive and motor regions of the dataset. Our study demonstrated that the driver's hand-foot coordination had distinct brain functional connectivity characteristics under different fatigue states, which could inform the design of neural network detection algorithms for driving fatigue.

The driver's behavior plays a crucial role in transportation safety. It is widely acknowledged that driver vigilance is a major contributor to traffic accidents. However, the quantitative impact of driver vigilance on driving risk has yet to be fully explored. This study aims to investigate the relationship between driver vigilance and driving risk, using data recorded from 28 drivers who maintain a speed of 80 km/h on a monotonous highway for 2 hours. The k-means and linear fitting methods are used to analyze the driving risk distribution under different driver vigilance states. Additionally, this study proposes a research framework for analyzing driving risk and develops three classification models (KNN, SVM, and DNN) to recognize the driving risk status. The results show that the frequency of low-risk incidents is negatively correlated with the driver's vigilance level, whereas the frequency of moderate-risk and high-risk incidents is positively correlated with the driver's vigilance level. The DNN model performs the best, achieving an accuracy of 0.972, recall of 0.972, precision of 0.973, and f1-score of 0.972, compared to KNN and SVM. This research could serve as a valuable reference for the design of warning systems and intelligent vehicles.

The trend toward intelligent connected vehicles (ICVs) led to numerous more novel and more natural human-vehicle relationships, which will bring about tremendous changes in smart cockpit functions and interaction methods. However, most in-vehicle human-machine interaction (HMI) systems focus on adding more functions, while few of them focus on the user experience (UX) of the system. This study presents an evaluation method of UX based on eye-tracking, finger movement tracking, and facial expression, the study also proposed a pleasantness prediction based on multi-layer perception (MLP) algorithm using multi-modal data. Through the UX experiment on two in-vehicle HMI systems, the study verified that the proposed evaluation method can be objective and efficient to evaluate the in-vehicle HMI system. Based on the MLP algorithm, the study trained the pleasantness prediction model using multi-modal data. Besides, we collected new data of the third in-vehicle HMI system to test the trained model and presented excellent test results.

The driver is an essential factor in the traffic system, and inexperienced drivers are special high-risk groups. We used electroencephalography (EEG) and reaction time to quantify the differences between experienced and novice drivers' risk perception and braking behaviour in a driving simulator. Twenty-seven participants were asked to drive through a 12-km dynamic scenario with EEG signals recorded simultaneously. There are mainly four frequency bands for human EEG activity: alpha, beta, theta, and delta. The power spectral density (PSD) of beta activity was analysed because it dominated when drivers braked in an emergency. The results indicate that the indicators of β activity and reaction time discriminated between the novice and experienced drivers. The reaction time of drivers was related to the increment of the β activity, indicating that the driver's risk perception stage will affect their risk reaction. The study provides us with the operating performance and internal physiological activities of drivers in the braking process.

ABSTRACTPrevious studies indicated that the elevated mesenchymal Wnt/β-catenin signaling deprived dental mesenchyme of odontogenic fate. By utilizing ex vivoor pharmacological approaches, Wnt/β-catenin signaling in the developing dental mesenchyme was suggested to suppress the odontogenic fate by disrupting the balance between Axin2 and Runx2. In our study, the Osr2-creKI; Ctnnb1ex3fmouse was used to explore how mesenchymal Wnt/β-catenin signaling suppressed the odontogenic fate in vivo. We found that all of the incisor and half of the molar germs of Osr2-creKI; Ctnnb1ex3fmice started to regress at E14.5 and almost disappeared at birth. The expression of Fgf3and Msx1was dramatically down-regulated in the E14.5 Osr2-creKI; Ctnnb1ex3fincisor and molar mesenchyme, while Runx2transcription was only diminished in incisor mesenchyme. Intriguingly, in the E14.5 Osr2-creKI; Ctnnb1ex3fincisor epithelium, the expression of Nogginwas activated, while Shhwas abrogated. Similarly, the Wnt and BMP antagonists, Ectodinand Nogginwere also ectopically activated in the E14.5 Osr2-creKI; Ctnnb1ex3fmolar epithelium. Recombination of E13.5 Osr2-creKI; Ctnnb1ex3fmolar mesenchyme with E10.5 and E13.5 WT dental epithelia failed to develop tooth. Taken together, the mesenchymal Wnt/β-catenin signaling resulted in the loss of odontogenic fate in vivonot only by directly suppressing odontogenic genes expression but also by inducing Wnt and BMP antagonists in dental epithelium.

ABSTRACTTooth development is accomplished by a series of epithelial-mesenchyme interactions. Epithelial Wnt/β-catenin signaling is sufficient to initiate tooth development by activating Shh, Bmps, Fgfsand Wntsin dental epithelium, which in turn, triggered the expression of odontogenic genes in the underlying mesenchyme. Although constitutive activation of Wnt/β-catenin signaling in oral ectoderm resulted in the continuous tooth formation throughout the life span, if the epithelial Wnt/β-catenin signaling could induce the mesenchyme other than oral mesenchyme still required to be elucidated. In this study, we found that in the K14-cre; Ctnnb1ex3fmice, the markers of dental epithelium, such as Pitx2, Shh, Bmp2, Fgf4, and Fgf8, were not only activated in the oral ectoderm, but also in the cheek epithelium. Surprisingly, the underlying cheek mesenchymal cells were elongated and expressed Dspp. Further investigations detected that the expression of Msx1and Runx2extended from oral to cheek mesenchyme. These findings suggested that epithelial Wnt/β-catenin signaling was capable of inducing Dsppexpression in non-dental mesenchyme. Moreover, Dsppexpression in the K14-cre; Ctnnb1ex3foral mesenchyme was activated earlier than that in the wild type littermates. In contrast, although the elongated oral epithelial cells were detected in the K14-cre; Ctnnb1ex3fmice, the Amelogeninexpression was suppressed. The differential effects of the persistent epithelial Wnt/β-catenin signaling on ameloblast and odontoblast differentiation might result from the altered BMP signaling. In summary, our findings suggested that the epithelial Wnt/β-catenin signaling could induce craniofacial mesenchyme into odontogenic program and promote odontoblast differentiation.