Other lines of evidence support the role of the CB1 receptor in depolarization-induced suppression of inhibition. This receptor is distributed very widely throughout the brain, covering all areas where depolarization-induced suppression of inhibition has been observed (Herkenham "et al." 1990). The CB1 receptor also appears to be expressed mainly on GABA-ergic pre-synaptic terminals, making it an excellent candidate for mediating depolarization-induced suppression of inhibition (Matyas "et al." 2006, Katona "et al." 1999). In 2005, other groups began to demonstrate the involvement of the CB1 receptor in DSI in other regions of the brain (Jo "et al." 2005, Bodor "et al." 2005). Lastly, depolarization-induced suppression of inhibition research was finally applied to mice that had the CB1 receptor genetically "knocked-out". So far, these knock-out mice are not known to exhibit DSI in any regions of the brain, suggesting that the CB1 receptor is the crucial mediator for DSI (Kreitzer & Regehr 2001a, Ohno-Shosaku "et al." 2002).