Decoding arm kinematic parameters from motor cortical ensemble activity using long short-term memory

Department of Human Factors EngineeringBrain machine interface (BMI) is the interface which converts the neural signal recorded from the subject into the intention such as arm movement or grasping. One of the key topic in the BMI research area is to decode the neural signal from the motor cortex in the brain and extract information related with the movement such as velocity, position and speed of arm. By interpreting the signal, the tetraplegia can get a chance to overcome the obstacle by controlling the robot arm according to their intention interacting with the environment. To achieve these goal, several algorithms such as Kalman Filter or optimal linear estimation have been used. Further, modern machine learning algorithms such as Long Short-Term Memory(LSTM) However, most of the decoders have focused on the decoding of the velocity parameter even though there were evidences that the neural activity of the primary motor cortex encodes the directional information and speed information differently. The developed decoder in this research reconstructed the velocity of an arm movement with two separate LSTM decoder, which is designed for individual decoding of speed and direction. Because there is neural evidence that the direction is encoded nonlinearly in the motor cortex and the speed variable has nonlinear characteristics, the nonlinear prediction algorithm, which is LSTM, was used as the predictor. Also, velocity Kalman filter (VKF) and velocity LSTM (VLSTM) were compared with the decoder. The performance was measured for the data provided from the Collaborative Research in Computational Neuroscience - Data sharing (CRCNS). The task was center ??? out reaching movement and the primary motor cortex signal of macaque monkey was recorded. Specifically, the correctness of the velocity reconstruction was tested with following measurements: angular difference, correlation coefficient, mean absolute error. Further, the correctness of the position reconstruction was tested with following measurements: Euclidean distance with true trajectory. Also, the effectiveness of the reconstructed trajectory was measured with following indexes: Euclidean distance with straight line from home to target, hit rate, distance to target according to the movement time, movement directional change (MDC), orthogonal directional change (ODC). The results in aspects of how accurately the decoder predicted the kinematics showed that the new decoder predicts the movement direction accurately than the other two decoders. The quality of position reconstruction of the SDLSTM was significantly better than the velocity Kalman filter and was similar with the VLSM. Also, the SDLSTM???s trajectory could be acquired the target in highest frequency. Also, the model complexity of the speed and direction predictor in the SDLSTM were different with each other. It implies that the encoding strategy of the two variables in the motor cortex can be different. Finally, we could identify that the SDLSTM increased the overall decoding performance.clos

Uncertainty and Climate Change Intervention: An Introduction to the Economics of Climate Change

The pressing reality of global climate change has resulted in a great deal of focus on proposals for market-based government intervention. Currently proposed intervention can take one of two forms: either it can achieve reductions in carbon emissions by controlling the quantity of allowable carbon emissions or it can do the same by setting the price of carbon emissions. If we approach the issue of climate change as a classic externality problem and assume perfect information, economic theory suggests that an optimal level of carbon abatement can be achieved by either method. But, with the issue of climate change we are dealing with a host of unknown costs and benefits of abatement, and we cannot be sure that either method will be efficient. Thus, the role of uncertainty must factor into any policy decision. In this paper, we apply theoretical concepts of informational uncertainty to the issue of climate change. We find that depending on the curvatures of the costs and benefit functions, one type of government intervention may be preferable to the other, with arguments made for each case. Our analysis will highlight the need for further research into the anthropogenic causes and effects of climate change, as well as the need for policymakers to consider the role uncertainty and the precautionary principle play when deciding what sort of government intervention policy to pursue

Households and heat stress: estimating the distributional consequences of climate change

Recent research documents the adverse causal impacts on health and productivity of extreme heat, which will worsen with climate change. In this paper, we assess the current distribution of heat exposure within countries, to explore possible distributional consequences of climate change through temperature. Combining survey data from 690,745 households across 52 countries with spatial data on climate, this paper suggests that the welfare impacts of added heat stress may be regressive within countries. We find: (1) a strong negative correlation between household wealth and warmer temperature in many hot countries; (2) a strong positive correlation between household wealth and warmer temperatures in many cold countries; and (3) that poorer individuals are more likely to work in occupations with greater exposure. While our analysis is descriptive rather than causal, our results suggest a larger vulnerability of poor people to heat extremes, and potentially significant distributional and poverty implications of climate change

Meaning-Making Coping Among Cancer Patients in Sweden and South Korea: A Comparative Perspective

The present study compared meaning-making coping among cancer patients in Sweden and South Korea, with a focus on the sociocultural context. Semi-structured interviews were conducted with 51 Swedes and 33 Koreans. The results showed significant differences between the two countries as well as similarities in existential, spiritual, and religious coping. For example, Swedes primarily used meaning-making coping as a means of meditation or relaxation, whereas Koreans relied on coping with prayer and using healthy foods as a means to survive. The present study confirms the significance of investigating cultural context when we explore the use of meaning-making coping among people who have experienced cancer.Meaning-making copin

Heat and learning

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