Shinosaki K, Inouye T, Ukai S, Toi S
Department of Neuropsychiatry, Osaka University Medical School, Japan.
Electroencephalogr Clin Neurophysiol. 1992 Dec;83(6):372-7. doi: 10.1016/0013-4694(92)90073-q.
Interhemispheric responses of alpha activity were investigated by use of half-field sinusoidally modulated light (SML) stimulation at the subject's alpha frequency. The left and right visual half-fields as well as full-field were separately stimulated by the SML. The power spectrum of SML responses, averaged with Wiener filtering, was obtained at the left and the right occipital area (O1 and O2) in 11 normal subjects. Power in each hemisphere, phase difference and coherence between O1 and O2 were estimated at an alpha frequency. A laterality index of power was defined as (P(l)-P(r))/(P(l) + P(r)) where P(l) is a power value at O1, and P(r) at O2. In most of the subjects, laterality index decreased in the order: left half-field, full-field and right half-field stimulation. This relationship revealed greater SML responses on the ipsilateral occipital area. There were significant differences in laterality index among 3 visual field conditions, thus showing that full-field responses ranged in lateralization between the left and right half-field responses in most of the subjects. This hemispheric distribution suggests that half-field SML stimulation affected alpha activity selectively in each hemisphere, mostly in the ipsilateral hemisphere.
通过使用以受试者的阿尔法频率进行半视野正弦调制光（SML）刺激，研究了阿尔法活动的半球间反应。SML分别对左、右视觉半视野以及全视野进行刺激。在11名正常受试者的左、右枕叶区域（O1和O2）获得了经维纳滤波平均后的SML反应的功率谱。在阿尔法频率下估计每个半球的功率、O1和O2之间的相位差以及相干性。功率的偏侧指数定义为（P(l)-P(r)）/（P(l)+P(r)），其中P(l)是O1处的功率值，P(r)是O2处的功率值。在大多数受试者中，偏侧指数按以下顺序降低：左半视野、全视野和右半视野刺激。这种关系表明同侧枕叶区域的SML反应更大。三种视野条件下的偏侧指数存在显著差异，因此表明在大多数受试者中，全视野反应的偏侧化介于左、右半视野反应之间。这种半球分布表明，半视野SML刺激主要在同侧半球选择性地影响每个半球的阿尔法活动。
