Current Medical Science

, Volume 38, Issue 5, pp 903–909 | Cite as

Effect of Paired Associative Stimulation on Motor Cortex Excitability in Rats

  • Xiang-yu Zhang
  • Yan-fang Sui
  • Tie-cheng GuoEmail author
  • Sai-hua Wang
  • Yan Hu
  • Yin-shan Lu


Paired associative stimulation (PAS), combining transcranial magnetic stimulation (TMS) with electrical peripheral nerve stimulation (PNS) in pairs with an optimal interstimulus interval (ISI) in between, has been shown to influence the excitability of the motor cortex (MC) in humans. However, the underlying mechanisms remain unclear. This study was designed to explore an optimal protocol of PAS, which can modulate the excitability of MC in rats, and to investigate the underlying mechanisms. The resting motor thresholds (RMTs) of TMS-elicited motor evoked potentials (MEPs) recorded from the gastrocnemius muscle and the latency of P1 component of somatosensory evoked potentials (SEPs) induced by electrical tibial nerve stimulation were determined in male Sprague-Dawley rats (n=10). Sixty rats were then randomly divided into 3 groups: a PAS group (further divided into 10 subgroups at various ISIs calculated by using the latency of P1, n=5, respectively), a TMS (only) group (n=5) and a PNS (only) group (n=5). Ninety repetitions of PAS, TMS and PNS were administered to the rats in the 3 groups, respectively, at the frequency of 0.05 Hz and the intensity of TMS at 120% RMT and that of PNS at 6 mA. RMTs and motor evoked potentials’ amplitude (MEPamp) were recorded before and immediately after the interventions. It was found that the MEPamp significantly decreased after PAS at ISI of 5 ms (P<0.05), while the MEPamp significantly increased after PAS at ISI of 15 ms, as compared with those before the intervention (P<0.05). However, the RMT did not change significantly after PAS at ISI of 5 ms or 15 ms (P>0.05). PAS at other ISIs as well as the sole use of TMS and PNS induced no remarkable changes in MEPamp and RMT. In conclusion, PAS can influence motor cortex excitability in rats. Neither TMS alone nor PNS alone shows significant effect.

Key words

paired associative stimulation transcranial magnetic stimulation peripheral nerves electrical stimulation resting motor thresholds motor evoked potentials somatosensory evoked potentials 


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Copyright information

© Huazhong University of Science and Technology 2018

Authors and Affiliations

  • Xiang-yu Zhang
    • 1
    • 2
  • Yan-fang Sui
    • 1
    • 3
  • Tie-cheng Guo
    • 1
    Email author
  • Sai-hua Wang
    • 1
    • 4
  • Yan Hu
    • 1
    • 5
  • Yin-shan Lu
    • 1
  1. 1.Department of Rehabilitation Medicine, Tongji Hospital, Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
  2. 2.Department of Rehabilitation Medicinethe 5th Hospital of Zhengzhou UniversityZhengzhouChina
  3. 3.Department of Rehabilitation Medicinethe 1st People’s Hospital of HaikouHaikouChina
  4. 4.Department of Rehabilitation Medicinethe 1st Hospital of WuhanWuhanChina
  5. 5.Department of Rehabilitation Medicine, Zhongnan HospitalWuhan UniversityWuhanChina

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