Study On Active Tactile Analysis And Decoding Of Macaques Under Visual Occlusion

Objective:The analysis of tactile related nerve signals based on invasive braincomputer interface is helpful to understand the working mechanism of nervous system and the treatment of nervous system diseases.At present,some researchers have carried out some research work on tactile analysis and reconstruction.However,due to the relatively limited understanding of the mechanism of neural information activity in the sensorimotor cortex,the sensory feedback-oriented BMI has some problems,such as few types of tactile reconstruction,unstable,unnatural.The performance of the braincomputer interface control system depends on the feedback information.Through the effective feedback of tactile and visual information during the control process,the control performance of the BMI system can be improved.Research based on behavioral and noninvasive brain imaging strategies has long focused on the potential of visual-tactile integration in improving human-computer interaction performance.However,there are relatively few studies on the mechanism of visual-tactile integration based on invasive cortical neural signal acquisition strategies.At present,there are only some research reports on the law of visual and tactile information processing integration using rats as models,which are close to actual human operation scenarios.The mechanism of visualtactile perception information processing and integration and its impact on the manipulation performance of brain-computer interface need to be further revealed.Therefore,the purpose of this study is to explore the following questions:(1)Exploring the effects of visual perception on cognitive behavior and neuronal activity mechanism of rhesus monkeys.(2)Exploring the neuronal activity patterns in different brain regions and different motor stages of rhesus monkeys and the mutual left and right mechanism of vision and touch in the shape discrimination task.(3)Detecting the effects of different decoders on the decoding accuracy of neural signals in single and multiple brain regions of rhesus monkeys.Methods: In this paper,two rhesus monkeys were taken as the research object.We design an active tactile resolution experimental device which could block vision was built to train rhesus monkeys to actively grasp shape discrimination task.Floating microelectrode arrays were implanted in the primary sensory cortex and posterior parietal cortex of rhesus monkeys,and the neural signals at different stages of the experiment were recorded.Focus on the effects of visual occlusion on behavior and sensorimotorrelated cortical neural activity in the process of active tactile exploration and discrimination in rhesus monkeys.By analyzing the behavioral data of rhesus monkeys,the emission rules of neurons and decoding of neural signals using Linear Discriminant Analysis(LDA),Support Vector Machine(SVM),Capsule Network(CAPSNET)decoders,to summary the interaction mechanism of vision and tactile sensation in related cortical activities.Results:1)In terms of behavioral characteristics,compared with the experiments with unblocked vision,the macaques in the shape recognition task without visual perception need to spend more time to complete the shape recognition task.The time was prolonged by 19.48%(p<0.001),39.71%(p<0.001),and 14.29%(p<0.001),respectively.2)Neurons have different activity patterns in different brain regions,different motor stages,and when grasping objects of different shapes.Touch-sensitive neurons in the S1 brain area significantly increased the spike firing rate when touching or grasping the target,and the spike firing rate was higher when the neuron was visually occluded.The brain area of PPC contains motor-sensitive neurons,which participate in the process of motor coding or execution.The activity is obvious in the motor stage,but the emission frequency of neural signals begins to decrease when the limb is at rest.In the whole neuronal activity of S1 and PPC brain regions,the neural activity of PPC brain region was significantly stronger than that of S1 brain region.After the visual information was blocked,the spike signal emission frequency of some channel neurons in PPC brain decreased significantly,while the spike signal emission frequency of some channels increased significantly,which proved that both visual perception and tactile perception could change the activity pattern of neurons in the cortex.3)According to the decoding results of spike signals under different threshold conditions,we find that except for the obvious fluctuation of decoding accuracy of LDA decoder,the decoding accuracy of SVM and CAPSNET decoders does not change obviously under different threshold conditions.In the decoding research based on the neural information of multiple brain regions,the CAPSNET decoder achieves an average decoding accuracy of 98.21% under the threshold of-4RMS.In the study of neural information decoding based on single brain region,CAPSNET achieved an average decoding accuracy of 94.42% and 97.03% in PPC and S1 brain regions,respectively.4)In terms of active tactile decoding based on neural signals in different brain regions,the decoding accuracy of multiple brain regions is not affected by blocking vision;but from the decoding accuracy of single brain region decoding,the decoding accuracy of PPC and S1 brain regions is significant changes have taken place.In the CAPSNET decoding results of macaque H,the average decoding accuracy of PPC brain region with visual perception is 93.4%,which is higher than the average decoding accuracy of 91.19%without visual perception,while the average decoding accuracy of S1 brain region with visual perception It is 95.91%,which is lower than the average decoding accuracy of97.07% without visual perception.Conclusions: Macaques can also have stable shape discrimination by relying on touch alone,but the combination of vision and touch is more efficient than relying on a single sense.Neurons in the S1 and PPC of macaques exhibit distinct activity patterns during different motor stages.The activity of touch-related brain regions is enhanced after visual perception is blocked,while the parietal cortex has a relatively complex function,and the impact of visual perception is not stably manifested in decoding accuracy.