Mulleners W M, Chronicle E P, Palmer J E, Koehler P J, Vredeveld J W
Department of Psychology, Lancaster University, Lancaster, UK.
Neurology. 2001 Jan 23;56(2):178-83. doi: 10.1212/wnl.56.2.178.
Results from transcranial magnetic stimulation (TMS) studies of visual cortex have confirmed visual cortical hyperexcitability in patients with migraine. It has been speculated that this may be due to deficient intracortical inhibitory tone. However, the TMS induction of phosphenes relies on the reporting of a subjective experience, and may thus be subject to bias.
Seven migraineurs with visual aura and seven sex- and age-matched controls were studied. Fifty-four different three-letter combinations were briefly displayed and followed by a magnetic pulse at 40, 70, 100, 130, 160, and 190 msec. Subjects were required to report as many letters as they thought they had recognized.
In the migraine group, the mean proportion of correctly identified letters was significantly higher at 100 msec, as was the proportion of trials with two or three letters correctly reported. The time window in which perceptual suppression could be introduced was narrower in migraineurs compared to controls.
These findings suggest that inhibitory systems are activated to a lesser extent by TMS pulses in patients. This observation is in agreement with the hypothesized deficiency of intracortical inhibition of the visual cortex, at least in migraineurs with aura.
经颅磁刺激（TMS）对视觉皮层的研究结果已证实偏头痛患者存在视觉皮层兴奋性过高的情况。据推测，这可能是由于皮质内抑制性张力不足所致。然而，TMS诱发光幻视依赖于主观体验的报告，因此可能存在偏差。
对7名有视觉先兆的偏头痛患者和7名性别及年龄匹配的对照者进行研究。简要显示54种不同的三个字母组合，然后在40、70、100、130、160和190毫秒时施加磁脉冲。要求受试者报告他们认为自己识别出的字母数量。
在偏头痛组中，100毫秒时正确识别字母的平均比例显著更高，正确报告两个或三个字母的试验比例也是如此。与对照组相比，偏头痛患者中可引入知觉抑制的时间窗口更窄。
这些发现表明，患者中TMS脉冲对抑制系统的激活程度较低。这一观察结果与视觉皮层皮质内抑制不足的假设相符，至少在有先兆的偏头痛患者中是如此。
