Biomedical subjects

Yasuharu Koike

Publications and source records attributed to Yasuharu Koike.

4 recordsLinked to original sources

PubMed2006

Prediction of arm trajectory from a small number of neuron activities in the primary motor cortex.

Monkey arm movement was reconstructed from neuron activities recorded in the primary motor cortex (Ml). We recorded single neuron activities from a monkey's Ml, while the animal performed an arm reaching task. We also recorded electromyographic (EMG) activity and movement trajectories during the task. First, we reconstructed the EMG signals from the neuron activities. The EMG signals were reliably reconstructed with a linear summation of the neuron activities. Next, we reconstructed joint angles from the reconstructed EMG signals with an artificial neural network model. The reconstructed trajectories of the hand position and elbow position showed good correlation with the actual arm movement. This model appropriately reflected the anatomical characteristics.

Action Potentials↗

PubMed2002

A method for estimating torque-vector directions of shoulder muscles using surface EMGs.

In this study, a new method is proposed to estimate the torque-vector directions of each shoulder muscle. The method is based on a multiple regression model that reconstructs shoulder torque, which is calculated from the hand force and posture, from the surface EMG of many muscles recorded simultaneously. The torque-vector directions of eleven shoulder muscles of four subjects were obtained at up to 30 different arm postures with this method. The mean confidence interval ( p< 0.05) of the estimated torque-vector direction of each subject was 7.7-10.6 degrees. The correlation coefficient between the measured shoulder torque and reconstructed shoulder torque was between 0.76-0.84. The results for majority of the muscles were in accordance with previous studies, and reasonable from the viewpoint of anatomy. The torque-vector directions of a muscle, which are estimated with this method, have more of a functional meaning than a pure anatomical or mechanical one. These indicate the direction of the shoulder torque accompanying the muscle activation for a normal shoulder action that involves the cooperative contraction of many muscles.

Adult↗

PubMed2002

A method for estimating torque-vector directions of shoulder muscles using surface EMGs.

In this study, a new method is proposed to estimate the torque-vector directions of each shoulder muscle. The method is based on a multiple regression model that reconstructs shoulder torque, which is calculated from the hand force and posture, from the surface EMG of many muscles recorded simultaneously. The torque-vector directions of eleven shoulder muscles of four subjects were obtained at up to 30 different arm postures with this method. The mean confidence interval (p < 0.05) of the estimated torque-vector direction of each subject was 7.7-10.6 degrees. The correlation coefficient between the measured shoulder torque and reconstructed shoulder torque was between 0.76-0.84. The results for majority of the muscles were in accordance with previous studies, and reasonable from the viewpoint of anatomy. The torque-vector directions of a muscle, which are estimated with this method, have more of a functional meaning than a pure anatomical or mechanical one. These indicate the direction of the shoulder torque accompanying the muscle activation for a normal shoulder action that involves the cooperative contraction of many muscles.

Adult↗

PubMed1996

A Kendama Learning Robot Based on Bi-directional Theory.

A general theory of movement-pattern perception based on bi-directional theory for sensory-motor integration can be used for motion capture and learning by watching in robotics. We demonstrate our methods using the game of Kendama, executed by the SARCOS Dextrous Slave Arm, which has a very similar kinematic structure to the human arm. Three ingredients have to be integrated for the successful execution of this task. The ingredients are (1) to extract via-points from a human movement trajectory using a forward-inverse relaxation model, (2) to treat via-points as a control variable while reconstructing the desired trajectory from all the via-points, and (3) to modify the via-points for successful execution. In order to test the validity of the via-point representation, we utilized a numerical model of the SARCOS arm, and examined the behavior of the system under several conditions. Copyright 1996 Elsevier Science Ltd.

Journal Article↗