PySurfer - learning examples

该文档是本人在阅读pysurfer的examples时把遇到的一些函数进行了摘录和注释，希望能对该软件的了解有所助益
详细例子见：http://pysurfer.github.io/examples/index.html

in plot_basics.py

Call the Brain object constructor with these parameters to initialize the visualization session.
sunject_id是被试编号，hemi是指定显示哪个半球等，surface是指定显示哪个皮层

brain = Brain(subject_id, hemi, surface)

in plot_fmri_activation.py

将激活数据（已经完成过体素到surfer的转换）overlay到之前打开的visualization session上，set threshold and showing only the positive activations.
brain.add_overlay(overlay_file,min=5,max=20,sign="pos")

You can then turn the overlay off.也就是说把overlay上去的激活从图中去掉
brain.overlays["sig"].remove()

这里为什么会出现”sig”？