Sustaining agriculture: policy, governance, and the future of family-based farming. A synthesis report of the collaborative research project 'policies that work for sustainable agriculture and regenerating rural livelihoods'.
Sustaining agriculture: policy, governance, and the future of family-based farming. A synthesis report of the collaborative research project 'policies that work for sustainable agriculture and regenerating rural livelihoods'.
复制标题
可持续农业：政策、治理和家庭农业的未来。
DOI：
10.1016/j.cortex.2018.03.001
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发表时间：
2002
期刊：
影响因子：
3.6
通讯作者：
W. Vorley
中科院分区：
文献类型：
--
作者：
B. Vorley;W. Vorley
通过经颅磁刺激诱发的运动诱发电位来评估皮质脊髓兴奋性是神经生理学中已建立的诊断工具，也是基础脑研究中广泛使用的程序。然而，最近人们越来越担心这些措施的可靠性低。在相同的采集条件下MEP的高变异性的一个可能原因可能是振荡神经元活动对皮质脊髓兴奋性的影响。基于研究表明，经颅交流电刺激可以夹带神经元振荡，我们在这里测试α或β频率tACS是否可以影响皮质脊髓兴奋性的相位依赖性的方式。我们在单独校准的α和β波段振荡频率下应用tACS，或者我们应用假tACS。同时单个TMS脉冲时间锁定到正在进行的tACS信号诱发MEP的八个等距相位。为了评估刺激频率的离线效应，在tACS之前和之后测量MEP幅度。为了评估tACS是否影响MEP幅度，我们将一个周期的正弦曲线拟合到在每个tACS频率的不同相位条件下引起的平均MEP。我们没有发现tACS的频率特异性离线效应。然而，MEP的β频率tACS调制是相位依赖性的。事后分析表明，这种影响是特定于低（<19 Hz）内在β频率的参与者。总之，通过显示β-tACS以相位依赖的方式影响MEP振幅，我们的结果支持神经元振荡在调节皮质脊髓兴奋性中的潜在作用。此外，我们的研究结果可能是有用的TMS协议，提高可靠性的MEP作为一个有意义的工具，用于研究应用或临床监测和诊断的发展。
The assessment of corticospinal excitability by means of transcranial magnetic stimulation-induced motor evoked potentials is an established diagnostic tool in neurophysiology and a widely used procedure in fundamental brain research. However, concern about low reliability of these measures has grown recently. One possible cause of high variability of MEPs under identical acquisition conditions could be the influence of oscillatory neuronal activity on corticospinal excitability. Based on research showing that transcranial alternating current stimulation can entrain neuronal oscillations we here test whether alpha or beta frequency tACS can influence corticospinal excitability in a phase-dependent manner. We applied tACS at individually calibrated alpha- and beta-band oscillation frequencies, or we applied sham tACS. Simultaneous single TMS pulses time locked to eight equidistant phases of the ongoing tACS signal evoked MEPs. To evaluate offline effects of stimulation frequency, MEP amplitudes were measured before and after tACS. To evaluate whether tACS influences MEP amplitude, we fitted one-cycle sinusoids to the average MEPs elicited at the different phase conditions of each tACS frequency. We found no frequency-specific offline effects of tACS. However, beta-frequency tACS modulation of MEPs was phase-dependent. Post hoc analyses suggested that this effect was specific to participants with low (<19 Hz) intrinsic beta frequency. In conclusion, by showing that beta tACS influences MEP amplitude in a phase-dependent manner, our results support a potential role attributed to neuronal oscillations in regulating corticospinal excitability. Moreover, our findings may be useful for the development of TMS protocols that improve the reliability of MEPs as a meaningful tool for research applications or for clinical monitoring and diagnosis.