Gene Duplications and Human Brain Evolution

We really don't know what instruct them to stop at specific presynaptic buttons. That's a major direction in our lab. There is evidence in the literature suggesting that even that first step is itself calcium dependent. So there could be some sort of a positive feedback, right? The calcium triggers their immobilization. But then the question is, why is 50% of presynaptic sites and not the 50%? And so we're embarking on a larger study trying to identify what distinguishes those presynaptic button locations.