title: Synchronization patterns suggest different functional organization in parietal reach region and dorsal premotor cortex.
abstract: The parietal reach region (PRR) and dorsal premotor cortex (PMd) form part of the fronto-parietal reach network. While neural selectivity profiles of single-cell activity in these areas can be remarkably similar, other data suggest that both areas serve different computational functions in visually guided reaching. Here we test the hypothesis that different neural functional organizations characterized by different neural synchronization patterns might be underlying the putatively different functional roles. We use cross-correlation analysis on single-unit activity (SUA) and multiunit activity (MUA) to determine the prevalence of synchronized neural ensembles within each area. First, we reliably find synchronization in PRR but not in PMd. Second, we demonstrate that synchronization in PRR is present in different cognitive states, including "idle" states prior to task-relevant instructions and without neural tuning. Third, we show that local field potentials (LFPs) in PRR but not PMd are characterized by an increased power and spike field coherence in the beta frequency range (12-30 Hz), further indicating stronger synchrony in PRR compared with PMd. Finally, we show that neurons with similar tuning properties tend to be correlated in their random spike rate fluctuations in PRR but not in PMd. Our data support the idea that PRR and PMd, despite striking similarity in single-cell tuning properties, are characterized by unequal local functional organization, which likely reflects different network architectures to support different functional roles within the fronto-parietal reach network.
authors.affiliation: Bernstein Center for Computational Neuroscience, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany; Systems Neurophysiology Group, Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany; and Department of Cognitive Neurology, Hertie Institute for Clinical Brain Research, Tübingen, Germany.
authors.forename: Shubhodeep
authors.initials: S
authors.lastname: Chakrabarti
authors.affiliation: Bernstein Center for Computational Neuroscience, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany;
authors.forename: Pablo
authors.initials: P
authors.lastname: Martinez-Vazquez
authors.affiliation: Bernstein Center for Computational Neuroscience, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany; agail@gwdg.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Gail
mesh_terms: D000200:Action Potentials; D000818:Animals; D058256:Brain Waves; D003344:Cortical Synchronization; D003627:Data Interpretation, Statistical; D008253:Macaca mulatta; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D065852:Spatial Memory / Q000502:physiology
keywords: cross-correlation analysis; posterior parietal cortex; visually guided reaching