The article "In vivo coincidence detection in mammalian sound localization generates phase delays", authored by Franken et al., attempts to further elucidate the mechanisms underlying ITD in mammalian brains. One experiment they performed was to isolate discrete inhibitory post-synaptic potentials to try and determine if inhibitory inputs to the superior olive were allowing the faster excitatory input to delay firing until the two signals were synced. However, after blocking EPSPs with a glutamate receptor blocker, they determine that the size of inhibitory inputs was too marginal to appear to play a significant role in phase locking. This was verified when the experimenters blocked inhibitory input and still saw clear phase locking of the excitatory inputs in their absence. This led them to the theory that in-phase excitatory inputs are summated such that the brain can process sound localization by counting the number of action potentials that arise from various magnitudes of summated depolarization.