title: Dissociated effects of quiet stance on standard and high-frequency (600 Hz) lower limb somatosensory evoked potentials.
abstract: OBJECTIVE
  To verify whether standing can modulate somatosensory input from lower limb to the cortex. Somatosensory afferents have been evaluated not only by means of somatosensory evoked potentials recorded by means of classical wide-bandpass filtering (standard SEPs), but also by high-frequency somatosensory evoked potentials (HF-SEPs), which probably play a role in the processing of rapid adaptive changes.
  
  
  METHODS
  Eight healthy subjects underwent right posterior tibial nerve (PTN) stimulation in two different conditions (standing and lying supine). Standard SEPs reflecting the activity of both subcortical and cortical generators further underwent digital filtering (300-800 Hz), in order to enhance HF-SEP components.
  
  
  RESULTS
  Stance significantly reduces the P40 cortical component of standard SEPs. By contrast, HF-SEPs did not show any significant change between the two conditions.
  
  
  CONCLUSIONS
  The lack of any gating effect on HF-SEPs lends further substance to the hypothesis that HF-SEPs play a pivotal role in the processing of somatosensory inputs related to rapid adaptive changes.
  
  
  CONCLUSIONS
  Our data confirm that standard and HF-SEPs reflect two distinct mechanisms with strongly different functional significance. Further studies are needed to definitively establish whether this dissociation is merely caused by the activation of anatomically different neuronal pools, or by the involvement of distinct functional mechanisms.
authors: IRCCS "La Nostra Famiglia - E. Medea", Polo Friuli Venezia Giulia, Via cialdini 29, 33037 Pasian di Prato, Udine, Italy. restuccia@pp.lnf.it
authors: Domenico
authors: D
authors: Restuccia
authors: Barbara
authors: B
authors: Micoli
authors: Monica
authors: M
authors: Cazzagon
authors: Rachele
authors: R
authors: Fantinel
authors: Ivana Del
authors: ID
authors: Piero
authors: Giacomo
authors: G
authors: Della Marca
mesh_terms: D000328:Adult; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005073:Evoked Potentials, Somatosensory / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000294:innervation*; D008297:Male; D008875:Middle Aged; D011187:Posture; D013003:Somatosensory Cortex / Q000502:physiology / Q000528:radiation effects*; D013057:Spectrum Analysis; D013979:Tibial Nerve / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors