title: Probing the reaching-grasping network in humans through multivoxel pattern decoding.
abstract: BACKGROUND
  The quest for a putative human homolog of the reaching-grasping network identified in monkeys has been the focus of many neuropsychological and neuroimaging studies in recent years. These studies have shown that the network underlying reaching-only and reach-to-grasp movements includes the superior parieto-occipital cortex (SPOC), the anterior part of the human intraparietal sulcus (hAIP), the ventral and the dorsal portion of the premotor cortex, and the primary motor cortex (M1). Recent evidence for a wider frontoparietal network coding for different aspects of reaching-only and reach-to-grasp actions calls for a more fine-grained assessment of the reaching-grasping network in humans by exploiting pattern decoding methods (multivoxel pattern analysis--MVPA).
  
  
  METHODS
  Here, we used MPVA on functional magnetic resonance imaging (fMRI) data to assess whether regions of the frontoparietal network discriminate between reaching-only and reach-to-grasp actions, natural and constrained grasping, different grasp types, and object sizes. Participants were required to perform either reaching-only movements or two reach-to-grasp types (precision or whole hand grasp) upon spherical objects of different sizes.
  
  
  RESULTS
  Multivoxel pattern analysis highlighted that, independently from the object size, all the selected regions of both hemispheres contribute in coding for grasp type, with the exception of SPOC and the right hAIP. Consistent with recent neurophysiological findings on monkeys, there was no evidence for a clear-cut distinction between a dorsomedial and a dorsolateral pathway that would be specialized for reaching-only and reach-to-grasp actions, respectively. Nevertheless, the comparison of decoding accuracy across brain areas highlighted their different contributions to reaching-only and grasping actions.
  
  
  CONCLUSIONS
  Altogether, our findings enrich the current knowledge regarding the functional role of key brain areas involved in the cortical control of reaching-only and reach-to-grasp actions in humans, by revealing novel fine-grained distinctions among action types within a wide frontoparietal network.
authors.affiliation: Department of General Psychology University of Padova Padova Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Di Bono
authors.affiliation: Department of General Psychology University of Padova Padova Italy ; Cognitive Neuroscience Center University of Padova Padova Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Begliomini
authors.affiliation: Department of General Psychology University of Padova Padova Italy ; Cognitive Neuroscience Center University of Padova Padova Italy ; Centro Interdisciplinare Beniamino Segre Accademia dei Lincei Roma Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Castiello
authors.affiliation: Department of General Psychology University of Padova Padova Italy ; Cognitive Neuroscience Center University of Padova Padova Italy ; IRCCS San Camillo Hospital Venice-Lido Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Zorzi
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006225:Hand / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D009068:Movement / Q000502:physiology; D009434:Neural Pathways / Q000502:physiology*; D009778:Occipital Lobe / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D013223:Statistics as Topic / Q000379:methods
keywords: Functional magnetic resonance imaging; multivoxel pattern decoding; reaching‐only action; visuomotor reach‐to‐grasp action