Motor imagery (MI) is an important paradigm of driving brain computer interface (BCI). However, MI is not easy to control or acquire, and the performance of MI-BCI depends heavily on the performance of the subjects' MI. Therefore, the correct execution of MI mental activities, ability evaluation and improvement methods play important and even critical roles in the improvement and application of MI-BCI system's performance. However, in the research and development of MI-BCI, the existing researches mainly focus on the decoding algorithm of MI, but do not pay enough attention to the above three aspects of MI mental activities. In this paper, these problems of MI-BCI are discussed in detail, and it is pointed out that the subjects tend to use visual motor imagery as kinesthetic motor imagery. In the future, we need to develop some objective, quantitatively visualized MI ability evaluation methods, and develop some effective and less time-consumption training methods to improve MI ability. It is also necessary to solve the differences and commonness of MI problems between and within individuals and MI-BCI illiteracy to a certain extent.
Algorithms ; Brain-Computer Interfaces ; Electroencephalography ; Humans ; Imagery, Psychotherapy ; Imagination

ObjectiveTo explore the influence of the core symptoms of attention deficit hyperactivity disorder （ADHD） on behavioral problems of children with ADHD propensity， so as to provide references for early identification and targeted intervention for children with ADHD propensity. MethodsFrom July to August 2021， 25 children with ADHD propensity were screened as the ADHD propensity group， and 25 children matched for age， gender and grade were included as the normal group in an elementary school in Guangzhou. ADHD core symptoms were assessed by the Chinese version of the Swanson Nolan and Pelham， version IV-parent form for ADHD （SNAP-IV）， and behavioral problems were assessed by Questionnaire-Children with Difficulties （QCD） and Conners Parental Symptom Questionnaire （PSQ）. Spearman correlation analysis was used to examine the correlation between ADHD core symptoms and QCD and PSQ scores， and hierarchical linear regression analysis was used to explore the effect of ADHD core symptoms on behavioral problems. Results① The differences between the groups showed that both attention deficit and hyperactivity-impulsivity factor scores were higher in the ADHD propensity group than those in the normal group （t=7.771， 6.726， P<0.01）. ② Correlation analysis showed that the attention deficit factor score was negatively correlated with QCD total score （r=-0.440， P<0.05）， and positively correlated with the learning problem factor score of PSQ （r=0.457， P<0.05）. The score of hyperactivity-impulsivity was negatively correlated with score of anxiety factor in PSQ （r=-0.457， P<0.05）， and positively correlated with impulse-hyperactivity factor score （r=0.552， P<0.01）. ③ Hierarchical linear regression analysis showed that the attention deficit factor score negatively predicted the total score of QCD （B=-0.682， P<0.05， R²=0.468）. The hyperactivity-impulsivity factor score had a negative predictive effect on the anxiety factor score of PSQ （B=-0.048， P<0.05， R²=0.367）， and had a positive predictive effect on the impulsivity-hyperactivity factor score （B=0.077， P<0.01， R²=0.424）. ConclusionChildren with ADHD propensity have significant attention deficit symptoms， hyperactivity-impulsivity symptoms and behavioral problems， and the attention deficit may be the main cause of their daily behavioral problems， while hyperactivity-impulsivity may be the main cause of their impulsive-hyperactivity problems.