I am looking into the rationale and reasons behind why researchers use the 70% threshold within MCAO models, and why smaller drops in CBF (cerebral blood flow - measured by laser doppler flowmetry) are discounted when MCA (middle cerebral artery) branching varies significantly between each rodent. Specifically I am trying to establish a start point for this rationale, with evidence to back this up. Does anyone know of any good papers regarding this? Many thanks