Guevara M A, Corsi-Cabrera M
Facultad de Psicología, Universidad, Nacional Autónoma de México, México, D.F., México.
Int J Psychophysiol. 1996 Oct;23(3):145-53. doi: 10.1016/s0167-8760(96)00038-4.
In view of the widespread use of electroencephalographic correlation (r) and coherence (Coh) analyses in studying brain functional relationships, it seems important to illustrate results yielded by both methods. Although they are considered as equivalent, they show important differences. Results obtained from r and Coh were compared using: (a) 2 Hz sinusoidal signals, where phase and amplitude were artificially manipulated and, (b) Coh and r spectra obtained between each pair of derivations (C3, C4, F3, F4, T3 and T4) from wakefulness, stage 2, stage 4 and paradoxical sleep (n = 8). The following results were obtained: significant Pearson product-moment coefficients were obtained between r and Coh spectra in the range of 0.86 to 0.96 for interhemispheric and 0.60 to 0.90, for intrahemispheric paris; as a result of principal component analyses, the same three frequency bands were formed for r and Coh spectra with the exception of one single bin; similar results for r and Coh were obtained by two-way ANOVAs (physiological stages by derivations). In conclusion, as expected, a high degree of comparability between r and Coh was observed under normal physiological conditions and with the use of good quality recordings.
鉴于脑电图相关性（r）分析和相干性（Coh）分析在研究脑功能关系方面的广泛应用，展示这两种方法产生的结果似乎很重要。尽管它们被认为是等效的，但它们显示出重要差异。使用以下方法比较了从r和Coh获得的结果：（a）2 Hz正弦信号，其中相位和幅度被人为操纵，以及（b）从清醒、2期、4期和异相睡眠（n = 8）中每对导联（C3、C4、F3、F4、T3和T4）之间获得的Coh和r频谱。获得了以下结果：半球间r和Coh频谱之间的Pearson积矩系数显著，范围为0.86至0.96，半球内对为0.60至0.90；主成分分析的结果是，除了一个单独的频段外，r和Coh频谱形成了相同的三个频段；通过双向方差分析（生理阶段×导联）获得了r和Coh的相似结果。总之，正如预期的那样，在正常生理条件下并使用高质量记录时，观察到r和Coh之间具有高度可比性。
