“…Calculations of Hb and HbO 2 concentration changes have been performed by the well established ''modified Beer-Lambert law'' [12,27,31,35]. There has been some controversy in the literature on whether neuronal activation should be monitored with Hb, HbO 2 , Oxygenation (HbO 2 -Hb), or total Hb (THb = HbO 2 + Hb) [1,7,10,11,15,24,27,28,[32][33][34]36]. While most of these studies stress that HbO 2 reflects neuronal activation more reliably and consistently, some others have shown that this effect is only global.…”