Govender Sendhil, Rosengren Sally M, Dennis Danielle L, Lim Louis J Z, Colebatch James G
Prince of Wales Clinical School and Neuroscience Research Australia, University of New South Wales, Randwick, Sydney, NSW, 2031, Australia.
Department of Neurology, Royal Prince Alfred Hospital, Missenden Rd, Camperdown, Sydney, NSW, 2050, Australia.
Exp Brain Res. 2016 Jan;234(1):141-9. doi: 10.1007/s00221-015-4441-3. Epub 2015 Sep 24.
We have studied the effects of stimulus phase on the latency and amplitude of cVEMPs and oVEMPs by reanalysing data from Lim et al. (Exp Brain Res 224:437-445, 2013) in which alternating phase was used. Responses for the different initial stimulus phase, either positive or negative, were separated and reaveraged. We found that the phase (compressive or rarefactive) of AC 500-Hz stimuli had no significant effect on either latency or amplitude of the responses. Conversely, phase (positive = motor towards subjects) did alter the effects of BC 500-Hz stimulation. For cVEMPs, phase consistently affected initial latency with earlier responses for positive stimuli, while, for stimulation at the mastoid, negative onset phase gave larger responses. For the oVEMP, effects were different for the two sites of BC stimulation. At the forehead, the response appeared to invert, whereas at the mastoid there appeared to be a delay of the initial response. Related to this, the effect of phase for the two sites was opposite: at the mastoid, positive responses were earlier but negative were larger (particularly for long stimuli). At the forehead, the effect was the opposite: negative onset stimuli evoked earlier responses, whereas positive onset evoked larger responses. These findings indicate a basic difference in the way that AC and BC stimuli activate vestibular receptors and also indicate that the effects of phase of BC stimulation depend on location. Stimulus alternation does little to affect the response to AC stimulation but obscures the effects of BC stimuli, particularly for the oVEMP.
我们通过重新分析Lim等人（《实验脑研究》224:437 - 445，2013年）使用交替相位的数据，研究了刺激相位对颈肌前庭诱发肌源性电位（cVEMPs）和眼肌前庭诱发肌源性电位（oVEMPs）潜伏期和波幅的影响。对不同初始刺激相位（正或负）的反应进行分离并重新平均。我们发现，500赫兹交流电（AC）刺激的相位（压缩或稀疏）对反应的潜伏期或波幅均无显著影响。相反，相位（正 = 朝向受试者的运动）确实改变了500赫兹骨导（BC）刺激的效果。对于cVEMPs，相位始终影响初始潜伏期，正刺激的反应更早，而对于乳突刺激，负起始相位产生的反应更大。对于oVEMP，在两个BC刺激部位的效果不同。在前额，反应似乎反转，而在乳突，初始反应似乎延迟。与此相关的是，两个部位的相位效应相反：在乳突，正反应更早但负反应更大（特别是对于长时间刺激）。在前额，效果相反：负起始刺激诱发更早的反应，而正起始刺激诱发更大的反应。这些发现表明AC和BC刺激激活前庭感受器的方式存在根本差异，也表明BC刺激相位的影响取决于位置。刺激交替对AC刺激的反应影响不大，但会掩盖BC刺激的效果，特别是对于oVEMP。
