Age-related changes across the primary and secondary somatosensory areas: An analysis of neuromagnetic oscillatory activities

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• 作者：Koichi Hagiwara^a ; ^{hagiwara-kyu@umin.ac.jp" class="auth_mail} ; Katsuya Ogata^a ; Tsuyoshi Okamoto^b ; Taira Uehara^c ; Naruhito Hironaga^a ; Hiroshi Shigeto^c ; Jun-ichi Kira^c ; Shozo Tobimatsu^a
• 关键词：Secondary somatosensory area (SII) ; Aging ; Oscillatory activity ; Phase-locking factor (PLF) ; Weighted phase-lag index (wPLI) ; Cortical disinhibition
• 刊名：Clinical Neurophysiology
• 出版年：May, 2014
• 年：2014
• 卷：125
• 期：5
• 页码：1021-1029
• 全文大小：2751 K

文摘

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.

Significance

We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.