title: Cortical correlates of susceptibility to upper limb freezing in Parkinson's disease.
abstract: Freezing behavior is an unmet symptom in Parkinson's disease (PD), which reflects its complex pathophysiology. Freezing behavior can emerge when attentional capacity is reduced, i.e. under dual task interference. In this study, we characterized the cortical network signatures underlying the susceptibility to freezing during continuous finger tapping.
  
  
  
  Fourteen PD patients with STN-DBS and thirteen age- and gender-matched healthy controls performed continuous tapping with the index finger as single motor task and during dual tasking. Synchronized EEG and mechanogram of the finger tapping were recorded. Subsequently, we analyzed cortical activity and cortico-cortical phase synchronization. We correlated these spectral measures with the biomechanically confirmed numbers of freezing episodes during finger tapping.
  
  
  
  During dual tasking compared to the single motor task, PD patients showed an increase of cortico-cortical phase synchronization over the left prefrontal area from 13 to 30Hz. This correlated with increased occurrence of freezing episodes. Interestingly, PD patients lacked the increase of prefrontal cortico-cortical synchronization from 4 to 7Hz during dual tasking as observed in healthy controls.
  
  
  
  Dual task interference led to an increase of left prefrontal beta band synchronization (13-30Hz) in PD and this increment predicted the number of freezing episodes. This increment may underscore the relevance of prefrontal executive dysfunction in freezing susceptibility.
  
  
  
  These findings enhance our understanding of the pathological network mechanisms behind increased susceptibility to freezing behavior.
authors.affiliation: Department of Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research (HIH), University of Tuebingen, Tuebingen, Germany; German Centre of Neurodegenerative Diseases (DZNE), University of Tuebingen, Tuebingen, Germany; Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany; Graduate School of Neural & Behavioral Sciences, International Max Planck Research School, University of Tuebingen, Tuebingen, Germany. Electronic address: marlieke.scholten@uni-tuebingen.de.
authors.forename: Marlieke
authors.initials: M
authors.lastname: Scholten
authors.affiliation: Division of Fetal and Transitional Medicine, Children's National Medical Center, Washington, DC, USA.
authors.forename: Rathinaswamy B
authors.initials: RB
authors.lastname: Govindan
authors.affiliation: Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany; MEG Center, University of Tuebingen, Tuebingen, Germany; CIMeC, Center of Mind/Brain Sciences, University of Trento, Italy.
authors.forename: Christoph
authors.initials: C
authors.lastname: Braun
authors.affiliation: Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behavior, Department of Neurology, Nijmegen, The Netherlands.
authors.forename: Bastiaan R
authors.initials: BR
authors.lastname: Bloem
authors.affiliation: Department of Psychiatry and Psychotherapy, University of Tuebingen, Tuebingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Plewnia
authors.affiliation: Department of Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research (HIH), University of Tuebingen, Tuebingen, Germany; German Centre of Neurodegenerative Diseases (DZNE), University of Tuebingen, Tuebingen, Germany; Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany; Clinical and Experimental Neuroscience, Luxembourg Center for Systems Biomedicine (LCSB), University of Luxembourg and Centre Hospitalier de Luxembourg (CHL), Luxembourg.
authors.forename: Rejko
authors.initials: R
authors.lastname: Krüger
authors.affiliation: Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany; Division of Functional and Restorative Neurosurgery, Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.
authors.forename: Alireza
authors.initials: A
authors.lastname: Gharabaghi
authors.affiliation: Department of Neurodegenerative Diseases and Hertie Institute for Clinical Brain Research (HIH), University of Tuebingen, Tuebingen, Germany; German Centre of Neurodegenerative Diseases (DZNE), University of Tuebingen, Tuebingen, Germany; Centre for Integrative Neuroscience (CIN), University of Tuebingen, Tuebingen, Germany. Electronic address: daniel.weiss@uni-tuebingen.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Weiss
mesh_terms: D000328:Adult; D000368:Aged; D001611:Beta Rhythm; D003344:Cortical Synchronization; D056344:Executive Function; D005260:Female; D005385:Fingers / Q000294:innervation* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D010300:Parkinson Disease / Q000503:physiopathology*; D017397:Prefrontal Cortex / Q000503:physiopathology*
keywords: Cortical activity; Electroencephalography; Global phase synchronization; Parkinson’s disease; Subthalamic nucleus deep brain stimulation; Upper limb freezing