title: Modulation of the ∽20-Hz motor-cortex rhythm to passive movement and tactile stimulation.
abstract: BACKGROUND
  Integration of afferent somatosensory input with motor-cortex output is essential for accurate movements. Prior studies have shown that tactile input modulates motor-cortex excitability, which is reflected in the reactivity of the ∽ 20-Hz motor-cortex rhythm. ∽ 20-Hz rebound is connected to inhibition or deactivation of motor cortex whereas suppression has been associated with increased motor cortex activity. Although tactile sense carries important information for controlling voluntary actions, proprioception likely provides the most essential feedback for motor control.
  
  
  METHODS
  To clarify how passive movement modulates motor-cortex excitability, we studied with magnetoencephalography (MEG) the amplitudes and peak latencies of suppression and rebound of the ∽ 20-Hz rhythm elicited by tactile stimulation and passive movement of right and left index fingers in 22 healthy volunteers.
  
  
  RESULTS
  Passive movement elicited a stronger and more robust ∽ 20-Hz rebound than tactile stimulation. In contrast, the suppression amplitudes did not differ between the two stimulus types.
  
  
  CONCLUSIONS
  Our findings suggest that suppression and rebound represent activity of two functionally distinct neuronal populations. The ∽ 20-Hz rebound to passive movement could be a suitable tool to study the functional state of the motor cortex both in healthy subjects and in patients with motor disorders.
authors: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science Espoo, Finland ; Aalto NeuroImaging, MEG-Core, Aalto University School of Science Espoo, Finland ; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital Finland.
authors: Eeva
authors: E
authors: Parkkonen
authors: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science Espoo, Finland ; Aalto NeuroImaging, MEG-Core, Aalto University School of Science Espoo, Finland ; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital Finland.
authors: Kristina
authors: K
authors: Laaksonen
authors: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science Espoo, Finland ; Aalto NeuroImaging, MEG-Core, Aalto University School of Science Espoo, Finland.
authors: Harri
authors: H
authors: Piitulainen
authors: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science Espoo, Finland ; Aalto NeuroImaging, MEG-Core, Aalto University School of Science Espoo, Finland.
authors: Lauri
authors: L
authors: Parkkonen
authors: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science Espoo, Finland ; Aalto NeuroImaging, MEG-Core, Aalto University School of Science Espoo, Finland ; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital Finland.
authors: Nina
authors: N
authors: Forss
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000502:physiology*; D014110:Touch / Q000502:physiology; D055698:Touch Perception / Q000502:physiology
keywords: Beta rebound; beta rhythm; magnetoencephalography; motor-cortex excitability; proprioception; sensorimotor integration