Objective To calculate the nonlinear features of motion in patients with chronic vestibular syndrome(CVS)using the largest Lyapunov exponent(LLE),and to verify the classification model's validity through machine learning algorithms.Methods A three-dimensional(3D)motion capture system was used to capture the joint motion trajectories of the subjects,which were determined using the LLE.The features of the chaotic trajectories were calculated as the input,and seven classifiers,namely the ID3 decision tree,Adaboost,C45 decision tree,Bayesian classification,Naive Bayes,and support vector machine,were used for classification.Results A total of 17 sets of trajectories from 16 joints were in the chaotic state,and the average energy,enhanced wavelength,and kurtosis of the motion trajectories in the experimental group showed significant differences(P<0.05).The ID3 decision tree classifier showed optimal performance with 100%prediction accuracy,recall,and F1-score.Conclusions Chaotic features may contain high personality differences in patients with CVS and can improve the accuracy of machine learning algorithms for recognition.These findings provide a reference for early identification and motor rehabilitation of patients with CVS.

OBJECTIVE: To investigate the persistent damage of learning and memory ability after the cessation of sub-chronic manganese(Mn)-exposure in rats. METHODS: Specific pathogen free weaning male SD rats were randomly divided into control group and low-, medium-and high-dose groups based on body weight, with 6 rats in each group. Rats were intraperitoneally injected with Mn chloride(MnCl_2·4 H_2O) at the concentrations of 0, 5, 10, or 20 mg/kg body weight, 5 days per week for 6 weeks and continued to be observed for 12 weeks after the cessation of Mn-exposure. During the experiment, the body mass of the rats was weighed. Learning and memory ability was evaluated by a Morris water-maze task at the 6 th weeks of Mn-exposure(cessation of Mn-exposure of week 0), the 6 th and 12 th week of the cessation of Mn-exposure. The organ coefficients of heart, liver, spleen, kidney and testicles were evaluated after the cessation of Mn-exposure on week 12. RESULTS: The body mass of the high-dose group was lower than that of the other 3 groups(P<0.05) at the 4 th and 6 th week of Mn-exposure and the 2 nd week of the cessation of Mn-exposure. There was no significant difference in body mass between the groups(P>0.05) on the 12 th week of the cessation of Mn-exposure. The escape latency of high-dose group was higher than that of the control group(P<0.05), and the number of platform crossings in the low-, medium-and high-dose groups were fewer than that in the control group(P<0.05) after the cessation of Mn-exposure. The escape latency was shorter and the numbers of platform crossings were higher on the 6 th and 12 th week of the cessation of Mn-exposure(P<0.05) when compared with that of the 6 th week of Mn-exposure rats. There was no statistical significance in the organ coefficients of heart, liver, spleen, kidney and testicles among the 4 groups at the 12 th week of the cessation of Mn-exposure in rats(P>0.05).CONCLUSION: Sub-chronic Mn exposure can impair learning and memory ability of rats, and the damage persists after the cessation of Mn-exposure.