title: Age-related changes across the primary and secondary somatosensory areas: an analysis of neuromagnetic oscillatory activities.
abstract: OBJECTIVE
  Age-related changes are well documented in the primary somatosensory cortex (SI). Based on previous somatosensory evoked potential studies, the amplitude of N20 typically increases with age probably due to cortical disinhibition. However, less is known about age-related change in the secondary somatosensory cortex (SII). The current study quantified age-related changes across SI and SII mainly based on oscillatory activity indices measured with magnetoencephalography.
  
  
  METHODS
  We recorded somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation in healthy young and old subjects and assessed major SEF components. Then, we evaluated the phase-locking factor (PLF) for local field synchrony on neural oscillations and the weighted phase-lag index (wPLI) for cortico-cortical synchrony between SI and SII.
  
  
  RESULTS
  PLF was significantly increased in SI along with the increased amplitude of N20m in the old subjects. PLF was also increased in SII associated with a shortened peak latency of SEFs. wPLI analysis revealed the increased coherent activity between SI and SII.
  
  
  CONCLUSIONS
  Our results suggest that the functional coupling between SI and SII is influenced by the cortical disinhibition due to normal aging.
  
  
  CONCLUSIONS
  We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.
authors.affiliation: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: hagiwara-kyu@umin.ac.jp.
authors.forename: Koichi
authors.initials: K
authors.lastname: Hagiwara
authors.affiliation: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Ogata
authors.affiliation: Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Okamoto
authors.affiliation: Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Taira
authors.initials: T
authors.lastname: Uehara
authors.affiliation: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Naruhito
authors.initials: N
authors.lastname: Hironaga
authors.affiliation: Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shigeto
authors.affiliation: Department of Neurology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Kira
authors.affiliation: Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Shozo
authors.initials: S
authors.lastname: Tobimatsu
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D010296:Parietal Lobe / Q000502:physiology; D013003:Somatosensory Cortex / Q000502:physiology*
keywords: Aging; Cortical disinhibition; Oscillatory activity; Phase-locking factor (PLF); Secondary somatosensory area (SII); Weighted phase-lag index (wPLI)