title: Low- and high-frequency subcortical SEP amplitude reduction during pure passive movement.
abstract: OBJECTIVE
  To investigate the effect of pure passive movement on both cortical and subcortical somatosensory evoked potentials (SEPs).
  
  
  METHODS
  Median nerve SEPs were recorded in 8 patients suffering from Parkinson's disease (PD) and two patients with essential tremor. PD patients underwent electrode implantation in the subthalamic (STN) nucleus (3 patients) and pedunculopontine (PPTg) nucleus (5 patients), while 2 patients with essential tremor were implanted in the ventral intermediate nucleus (VIM) of the thalamus. In anesthetized patients, SEPs were recorded at rest and during a passive movement of the thumb of the stimulated wrist from the intracranial electrode contacts and from the scalp. Also the high-frequency oscillations (HFOs) were analyzed.
  
  
  RESULTS
  Amplitudes of both deep and scalp components were decreased during passive movement, but the reduction was higher at cortical than subcortical level. Also the HFOs were reduced by movement.
  
  
  CONCLUSIONS
  The different amount of the movement-related decrease suggests that the cortical SEP gating is not only the result of a subcortical somatosensory volley attenuation, but a further mechanism acting at cortical level should be considered.
  
  
  CONCLUSIONS
  Our results are important for understanding the physiological mechanism of the sensory-motor interaction during passive movement.
authors.affiliation: Unità Operativa di Neurofisiopatologia, CTO, Via S. Nemesio 21, 00145 Rome, Italy. Electronic address: angelo.insola@virgilio.it.
authors.forename: Angelo
authors.initials: A
authors.lastname: Insola
authors.affiliation: Istituto di Neurologia, Università Cattolica del Sacro Cuore, Rome, Italy; Fondazione Don Carlo Gnocchi Onlus, Milan, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Padua
authors.affiliation: Unità Operativa di Neurochirurgia funzionale e stereotassica, CTO, Via S. Nemesio 21, 00145 Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Mazzone
authors.affiliation: Divisione di Neurologia, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy; Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Valeriani
mesh_terms: D000368:Aged; D004567:Electrodes, Implanted; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D065846:Nucleus Raphe Magnus / Q000502:physiology*; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology; D020531:Subthalamic Nucleus / Q000502:physiology*
keywords: Deep brain stimulation; Gating; High frequency oscillations; Sensory–motor interaction; Somatosensory evoked potential