There are few researches on the modulation effect of transcranial direct current stimulation(tDCS) on complex spatial cognition. Especially, the influence of tDCS on the neural electrophysiological response in spatial cognition is not yet clear. This study selected the classic spatial cognition task paradigm (three-dimensional mental rotation task) as the research object. By comparing the changes in behavior and event-related potentials in different modes of tDCS before, during and after the application of tDCS, this study analyzed the behavioral and neurophysiological effects of tDCS on mental rotation. The comparison between active-tDCS and sham-tDCS showed no statistically significant difference in behavior between different stimulation modes. Still, the changes in the amplitudes of P2 and P3 during the stimulation were statistically significant. Compared with sham-tDCS, the amplitudes of P2 and P3 in active-tDCS mode showed a greater decrease during the stimulation. This study clarifies the influence of tDCS on the event-related potentials of the mental rotation task. It shows that tDCS may improve the brain information processing efficiency during the mental rotation task. Also, this study provides a reference for an in-depth understanding and exploration of the modulation effect of tDCS on complex spatial cognition.
Biometrics plays an important role in information society. As a new type of biometrics, electroencephalogram (EEG) signals have special advantages in terms of versatility, durability, and safety. At present, the researches on individual identification approaches based on EEG signals draw lots of attention. Identity feature extraction is an important step to achieve good identification performance. How to combine the characteristics of EEG data to better extract the difference information in EEG signals is a research hotspots in the field of identity identification based on EEG in recent years. This article reviewed the commonly used identity feature extraction methods based on EEG signals, including single-channel features, inter-channel features, deep learning methods and spatial filter-based feature extraction methods, etc. and explained the basic principles application methods and related achievements of various feature extraction methods. Finally, we summarized the current problems and forecast the development trend.
As the most common active brain-computer interaction paradigm, motor imagery brain-computer interface (MI-BCI) suffers from the bottleneck problems of small instruction set and low accuracy, and its information transmission rate (ITR) and practical application are severely limited. In this study, we designed 6-class imagination actions, collected electroencephalogram (EEG) signals from 19 subjects, and studied the effect of collaborative brain-computer interface (cBCI) collaboration strategy on MI-BCI classification performance, the effects of changes in different group sizes and fusion strategies on group multi-classification performance are compared. The results showed that the most suitable group size was 4 people, and the best fusion strategy was decision fusion. In this condition, the classification accuracy of the group reached 77%, which was higher than that of the feature fusion strategy under the same group size (77.31% vs. 56.34%), and was significantly higher than that of the average single user (77.31% vs. 44.90%). The research in this paper proves that the cBCI collaboration strategy can effectively improve the MI-BCI classification performance, which lays the foundation for MI-cBCI research and its future application.
ObjectiveTo investigate perioperative safety of laparoscopic pancreaticoduodenectomy (LPD) in elderly patients (age ≥70 years old).MethodsThe retrospective cohort study was conducted. The clinicopathologic data of the patients underwent LPD and open pancreaticoduodenectomy (OPD) in the Affiliated Hospital of North Sichuan Medical College from January 2016 to December 2019 were collected. The patients who met the inclusion and exclusion criteria were divided into LPD with aged ≥70 years old group (group A), OPD with aged ≥70 years old group (group B), and LPD with aged <70 years old group (group C). The baseline data, intraoperative situations, and postoperative situations were compared between the group A and group B, and between the group A and group C, respectively.Results① There were no statistic differences in the age, gender, body mass index, hemoglobin, albumin, and total bilirubin, American Society of Anesthesiologists (ASA) grade, and comorbidity index before operation between the group A and group B (P>0.05). However, there were statistic differences in the hemoglobin, albumin, ASA grade, and comorbidity index before operation between the group A and group C (P<0.05). ② There were no significant differences in the operation time between the group A and group B (P>0.05), but the intraoperative blood loss of the group A was significantly less than the group B (P<0.05). The operation time, intraoperative blood loss, and conversion rate had no significant differences between the group A and group C (P>0.05). ③ There were no significant differences in the pathological pattern, tumor size, R0 resection rate, reoperative rate, and postoperative 90 d mortality between the group A and group B, and between the group A and group C, respectively. For the elderly patients, cases in the ICU, overall complications, specific complications (except for delayed gastric emptying) and Clavien-Dindo classification of complication after operation had no significant differences between the group A and group B (P>0.05), but there were more harvesting lymph nodes, lower postoperative pain score, shorter postoperative hospital stay, and less delayed gastric emptying cases in the group A than the group B (P<0.05). For the patients accepted LPD, there were no significant differences in the harvesting lymph nodes, postoperative pain score, postoperative hospital stay, and specific complications (except for pulmonary infection rate) between the group A and the group C (P>0.05), but the postoperative cases in the ICU were more, pulmonary infection rate was higher, overall complications rate and the ratio of Clavien-Dindo Ⅲ–Ⅳ classification of complication were higher in the group A as compared with the group C (P<0.05). ConclusionCompared with OPD, LPD might have some advantages in blood loss, harvesting lymph nodes, and recovery after surgery, even though perioperative safety of LPD in elderly patients is inferior to younger patients.