Apositron emission tomography study that was featured in the focus on neuroscience box "the mysterious placebo effect" demonstrated that a placebo painkiller:

Activates the same brain areas as genuine painkillers

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.