In order to improve the activation of the mirror neuron system and the ability of the visual-cued motor imagery further, the multi-stimuli-cued unilateral lower limb motor imagery is studied in this paper. The visual-auditory evoked pathway is proposed and the sensory process is studied. To analyze the visual-auditory interactions, the kinesthetic motor imagery with the visual-auditory stimulus, visual stimulus and no stimulus are involved. The motor-related rhythm suppression is applied on quantitative evaluation. To explore the statistical sensory process, the causal relationships among the functional areas and the event-related potentials are investigated. The results have demonstrated the outstanding performances of the visual-auditory evoked motor imagery on the improvement of the mirror neuron system activation and the motor imagery ability. Besides, the abundant information interactions among functional areas and the positive impacts of the auditory stimulus in the motor and the visual areas have been revealed. The possibility that the sensory processes evoked by the visual-auditory interactions differ from the one elicited by kinesthetic motor imagery, has also been indicated. This study will promisingly offer an efficient way to motor rehabilitation, thus favorable for hemiparesis and partial paralysis patients.

Autonomous sensory meridian response is believed as a perceptual phenomenon to specific sensory stimuli. To explore the underlying mechanism and emotional effect, the EEG under video and audio triggers of autonomous sensory meridian response was analyzed. The differential entropy and power spectral density by Burg method on δ, θ, α, β, γ and high γ frequencies were employed as quantitative features. The results indicate that the modulation of autonomous sensory meridian response on brain activities is broadband. Video trigger owns better performance of autonomous sensory meridian response than other triggers. Moreover, the results also reveal that autonomous sensory meridian response has a close relationship with neuroticism and its three sub-dimensions, anxiety, self-consciousness and vulnerability, with the scores of self-rating depression scale, but without emotions, happiness, sadness, or fear. This suggests that the responders of autonomous sensory meridian response may have the tendencies of neuroticism and depressive disorder.

Mental fatigue is a common psychobiological state elected by prolonged cognitive activities. Although, the performance and the disadvantage of the mental fatigue have been well known, its connectivity among the multiareas of the brain has not been thoroughly studied yet. This is important for the clarification of the mental fatigue mechanism. However, the common method of connectivity analysis based on EEG cannot get rid of the interference from strong noise. In this paper, an adaptive feature extraction model based on stacked denoising autoencoder has been proposed. The signal to noise ratio of the extracted feature has been analyzed. Compared with principal component analysis, the proposed method can significantly improve the signal to noise ratio and suppress the noise interference. The proposed method has been applied on the analysis of mental fatigue connectivity. The causal connectivity among the frontal, motor, parietal, and visual areas under the awake, fatigue, and sleep deprivation conditions has been analyzed, and different patterns of connectivity between conditions have been revealed. The connectivity direction under awake condition and sleep deprivation condition is opposite. Moreover, there is a complex and bidirectional connectivity relationship, from the anterior areas to the posterior areas and from the posterior areas to the anterior areas, under fatigue condition. These results imply that there are different brain patterns on the three conditions. This study provides an effective method for EEG analysis. It may be favorable to disclose the underlying mechanism of mental fatigue by connectivity analysis.

Motor imagery (MI) as an important way of motor learning has been studied widely. The visual task stimulus is an efficient way to improve MI abilities; however, its impact mechanism on motor training is still obscure. This study aimed to explore the influence of visual task stimulus on MI during continuous training. Three types of kinesthetic motor imageries, including a visual task stimulus, a visual stimulus, or no stimulus, were assessed. Brain lateralization and the variations of the event-related desynchronization were investigated. The results demonstrated a greater improvement motor performance after a visual task stimulus. The MI evoked by the visual task shows the most complex event-related lateralization (ERL) among the three contexts, with the presence of many ERL components. These results reveal a complex process of planning, attention focusing, and information processing on the brain, and the complexity of the information process increases with the one of external visual stimulus. This work provides a promising foundation for the incorporation of visual-task stimuli as a strategy to improve motor ability during motor training and motor rehabilitation.

Most contemporary hand robots only consider the palmar opposition as the thumb opposition, while ignoring the important role of the opposition of little finger. Consequently, the back of the hand is considered as a rigid, immovable structure. This letter investigated the influence of little finger opposition on hand grip performance through several research endeavors, including mechanical modeling and analysis of palmar opposition, optimization of the palmar-driving strategy, and prototype experiments on hand grip. First, we developed a kinematic model of palmar opposition based on the hand's anatomy and function of the transverse arch. We then employed elastic mechanics analysis methods to investigate the potential energy variations of the model during gripping. Second, we proposed an integrated palm-driving strategy and measured the deformation of the hand during the grasping process. Third, we designed and manufactured a hand rehabilitation exoskeleton that incorporates both the palmar opposition of the thumb and little finger. Finally, we conducted comparative experiments on grasping performance using the hand exoskeleton. Analysis results confirm the important role of the little finger opposition in maintaining hand grasping stability and enhancing grasping strength. These findings offer valuable insights for the research of hand function rehabilitation and high-performance robotic hands.

The electron paramagnetic resonance (EPR) parameters (the anisotropic g factors, the hyperfine structure parameters and the quadrupole coupling constant Q) and local structure for Cu²⁺ in BeO are theoretically investigated from the perturbation formulas of these parameters for a 3d⁹ ion under trigonally distorted tetrahedra. The ligand orbital and spin-orbit coupling contributions are included in the basis of the cluster approach, in view of the strong covalency of the [CuO₄]⁶⁻ cluster. From the calculations, the impurity Cu²⁺ is suggested not to occupy exactly the ideal Be²⁺ site but to suffer a slight inward displacement (≈0.024 Å) toward the ligand triangle along the C₃ axis. The theoretical EPR parameters show good agreement with the experimental data.