Iannetti G D, Leandri M, Truini A, Zambreanu L, Cruccu G, Tracey I
Department of Human Anatomy and Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
Clin Neurophysiol. 2004 Nov;115(11):2629-37. doi: 10.1016/j.clinph.2004.05.023.
To disclose a possible effect of duration of pulsed laser heat stimuli on Adelta nociceptor responses, skin temperature profiles, brain evoked potentials and pain perception.
We used a laser stimulator which works in the millisecond range and allows us to change the duration of the pulse while keeping the total energy of the stimulus constant. In 10 healthy volunteers, we measured the intensity of perceived pain with a 0-10 scale and the latency and amplitude of the early N1 and late N2 components of the scalp potentials evoked by laser pulses of equal energy and three different stimulus durations (2, 10, and 20 ms). Using a specifically developed pyrometer with a temporal resolution lower than 1 ms we also measured stimulus-induced changes of skin temperature.
Stimulus duration significantly influenced temperature rise times, pain perception, and brain potentials. Shorter stimulus durations yielded steeper slopes in the skin temperature profiles and higher pain ratings, shortened the latency of the N1 and N2 components, and increased the amplitude of N1.
The shorter stimulus duration shortens receptor activation times and yields a more synchronous afferent volley, thus providing a stronger spatial-temporal summation at central synapses that enhances intensity of first pain and brain potentials. This may prove useful in clinical applications.
揭示脉冲激光热刺激持续时间对Aδ伤害感受器反应、皮肤温度分布、脑诱发电位和疼痛感知的可能影响。
我们使用了一种工作在毫秒范围内的激光刺激器，它能让我们在保持刺激总能量恒定的同时改变脉冲持续时间。在10名健康志愿者中，我们用0至10分制测量了疼痛感知强度，以及由能量相等且刺激持续时间分别为2、10和20毫秒的三种不同激光脉冲诱发的头皮电位早期N1和晚期N2成分的潜伏期和波幅。我们还使用了一种专门开发的时间分辨率低于1毫秒的高温计来测量刺激引起的皮肤温度变化。
刺激持续时间显著影响温度上升时间、疼痛感知和脑电位。较短的刺激持续时间在皮肤温度分布中产生更陡的斜率和更高的疼痛评分，缩短了N1和N2成分的潜伏期，并增加了N1的波幅。
较短的刺激持续时间缩短了感受器激活时间，并产生更同步的传入冲动，从而在中枢突触处提供更强的时空总和，增强了第一痛觉和脑电位的强度。这在临床应用中可能会被证明是有用的。
