title: A four-dimensional virtual hand brain-machine interface using active dimension selection.
abstract: Brain-machine interfaces (BMI) traditionally rely on a fixed, linear transformation from neural signals to an output state-space. In this study, the assumption that a BMI must control a fixed, orthogonal basis set was challenged and a novel active dimension selection (ADS) decoder was explored.
  
  
  
  ADS utilizes a two stage decoder by using neural signals to both (i) select an active dimension being controlled and (ii) control the velocity along the selected dimension. ADS decoding was tested in a monkey using 16 single units from premotor and primary motor cortex to successfully control a virtual hand avatar to move to eight different postures.
  
  
  
  Following training with the ADS decoder to control 2, 3, and then 4 dimensions, each emulating a grasp shape of the hand, performance reached 93% correct with a bit rate of 2.4 bits s(-1) for eight targets. Selection of eight targets using ADS control was more efficient, as measured by bit rate, than either full four-dimensional control or computer assisted one-dimensional control.
  
  
  
  ADS decoding allows a user to quickly and efficiently select different hand postures. This novel decoding scheme represents a potential method to reduce the complexity of high-dimension BMI control of the hand.
authors.affiliation: Department of Neuroscience, University of Rochester Medical Center, 601 Elmwood Avenue, Box 603 Rochester, NY 14642, USA. Department of Neurology, University of Rochester, Rochester, NY, USA. Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Rouse
mesh_terms: D000465:Algorithms; D000818:Animals; D062207:Brain-Computer Interfaces; D003118:Color Perception / Q000502:physiology; D003198:Computer Simulation; D003216:Conditioning, Operant / Q000502:physiology; D005556:Form Perception / Q000502:physiology; D006225:Hand; D018737:Hand Strength / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D058117:Neural Prostheses; D011187:Posture / Q000502:physiology