title: Hand Shape Representations in the Human Posterior Parietal Cortex.
abstract: Humans shape their hands to grasp, manipulate objects, and to communicate. From nonhuman primate studies, we know that visual and motor properties for grasps can be derived from cells in the posterior parietal cortex (PPC). Are non-grasp-related hand shapes in humans represented similarly? Here we show for the first time how single neurons in the PPC of humans are selective for particular imagined hand shapes independent of graspable objects. We find that motor imagery to shape the hand can be successfully decoded from the PPC by implementing a version of the popular Rock-Paper-Scissors game and its extension Rock-Paper-Scissors-Lizard-Spock. By simultaneous presentation of visual and auditory cues, we can discriminate motor imagery from visual information and show differences in auditory and visual information processing in the PPC. These results also demonstrate that neural signals from human PPC can be used to drive a dexterous cortical neuroprosthesis.
  
  
  CONCLUSIONS
  This study shows for the first time hand-shape decoding from human PPC. Unlike nonhuman primate studies in which the visual stimuli are the objects to be grasped, the visually cued hand shapes that we use are independent of the stimuli. Furthermore, we can show that distinct neuronal populations are activated for the visual cue and the imagined hand shape. Additionally we found that auditory and visual stimuli that cue the same hand shape are processed differently in PPC. Early on in a trial, only the visual stimuli and not the auditory stimuli can be decoded. During the later stages of a trial, the motor imagery for a particular hand shape can be decoded for both modalities.
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Christian
authors.initials: C
authors.lastname: Klaes
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Spencer
authors.initials: S
authors.lastname: Kellis
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Tyson
authors.initials: T
authors.lastname: Aflalo
authors.affiliation: Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California, Los Angeles, California 90033, and.
authors.forename: Brian
authors.initials: B
authors.lastname: Lee
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125.
authors.forename: Kelsie
authors.initials: K
authors.lastname: Pejsa
authors.affiliation: Rancho Los Amigos National Rehabilitation Center, Downey, California 90242.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Shanfield
authors.affiliation: Rancho Los Amigos National Rehabilitation Center, Downey, California 90242.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hayes-Jackson
authors.affiliation: Rancho Los Amigos National Rehabilitation Center, Downey, California 90242.
authors.forename: Mindy
authors.initials: M
authors.lastname: Aisen
authors.affiliation: Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California, Los Angeles, California 90033, and.
authors.forename: Christi
authors.initials: C
authors.lastname: Heck
authors.affiliation: Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California, Los Angeles, California 90033, and.
authors.forename: Charles
authors.initials: C
authors.lastname: Liu
authors.affiliation: Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, andersen@vis.caltech.edu.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Andersen
mesh_terms: D000161:Acoustic Stimulation; D001931:Brain Mapping; D003463:Cues; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007092:Imagination / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D009068:Movement; D009474:Neurons / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000098:blood supply / Q000166:cytology / Q000502:physiology*; D010775:Photic Stimulation
chemical_list: D010100:Oxygen
keywords: audio processing; brain–machine interface; grasping; hand shaping; motor imagery; posterior parietal cortex