Figure 1. ‘Conditioning’ paradigms to protect the brain.

Typically, preconditioning uses a sublethal stimulus given minutes or days before the insult against which it aims to protect. Stuttering reperfusion is the prototypical per- or postconditioning strategy, by which one aims to prevent ‘reperfusion damage’ by repetitively opening and blocking brain perfusion before permanent reperfusion is allowed. Remote ischaemia is another per- or postconditioning strategy which typically produces repetitive, short phases of ischaemia of a peripheral limb to induce humoral and neural mechanisms of protection of a remote organ, such as the brain. Pharmacological mimics are drugs that either boost endogenous protective signalling cascades (such as the HIF pathway), or exogenously provide the effectors of endogenous protection, such as EPO.