This title seems very misleading given the study described. They have found a correlation between some neurons firing in sequence and a list of words being spoken from memory. We don't have any concrete understanding of how memories are really encoded, stored, and recalled. Indeed, we don't even know if "encoded", "stored", and "recalled" are useful approximations for what's really going on in there. So suggesting that we have found some specific time keeping module seems awfully hand-wavy (at best) to me.