Department of Pathophysiological Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Department of Physical and Occupational Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Clin Neurophysiol. 2015 Jun;126(6):1228-1233. doi: 10.1016/j.clinph.2014.09.018. Epub 2014 Sep 28.
The aim of the study was to investigate the functional differences between N20m and P30m components of somatosensory-evoked magnetic cortical field (SEF) in young and senior subjects.
Twenty-nine healthy subjects, 13 younger (mean age: 21.8years) and 16 senior (63.8 years), participated. Magnetic fields were measured using a 160-channel, whole head MEG. Single- and paired-pulse stimulations of 200 artifact-free MEG signal epochs were averaged separately. We calculated how aging affects recovery function of SEFs.
The senior showed a prolonged N20m peak latency compared to the younger, although the P30m peak latency was not significantly different between groups. The N20m ratios at 60 and 80 ms in the senior were significantly increased compared to the ratios in the younger (60 ms: P<0.05, 80 ms: P<0.001). The P30m ratios at inter-stimulus interval (ISI) of 80 and 100 ms showed even disinhibition in the senior than in the younger (P<0.05). The younger also showed a significantly negative correlation between P30m and N20m components' recovery curves (R=0.72, P<0.05).
Aging-related changes that occurred in recovery functioning were the decrease in N20m component suppression and the increase in P30m component recovery, indicating that the N20m and P30m components have different functions in aging-related recovery changes.
Our results show that the N20m ratio at an ISI of 80 ms was significantly increased in the senior group, indicating that the second stimulus-evoked SEF was less inhibited by the initial stimulus at this ISI, suggesting less refractory effect or increased disinhibition.
本研究旨在探讨年轻和老年受试者体感诱发电皮质磁场（SEF）的 N20m 和 P30m 成分之间的功能差异。
29 名健康受试者参与了本研究，其中 13 名年轻受试者（平均年龄：21.8 岁）和 16 名老年受试者（63.8 岁）。使用 160 通道全头 MEG 测量磁场。分别对 200 个无伪迹 MEG 信号时程的单刺激和双刺激进行平均。我们计算了衰老如何影响 SEF 的恢复功能。
与年轻受试者相比，老年受试者的 N20m 峰潜伏期延长，尽管两组之间的 P30m 峰潜伏期没有显著差异。与年轻受试者相比，老年受试者的 N20m 在 60 和 80ms 时的比值显著增加（60ms：P<0.05，80ms：P<0.001）。在 80 和 100ms 的刺激间隔（ISI）下，老年受试者的 P30m 比值甚至比年轻受试者的比值更高（P<0.05）。年轻受试者的 P30m 与 N20m 成分恢复曲线之间也存在显著的负相关（R=0.72，P<0.05）。
在恢复功能中发生的与衰老相关的变化是 N20m 成分抑制的减少和 P30m 成分恢复的增加，这表明 N20m 和 P30m 成分在与衰老相关的恢复变化中具有不同的功能。
我们的研究结果表明，老年组在 80ms 的 ISI 下 N20m 比值显著增加，这表明在该 ISI 下，第二个刺激诱发的 SEF 受到初始刺激的抑制程度较小，提示抑制作用降低或抑制作用增加。
