What exactly is rebirth? According to Buddhism, one's self is made of 5 agregates. But these agregagtes should dissolve at death, because according to neurosciences,feeling, perception, thinking and conscience are just functions of the brain, which is destroyed at one's death. So what links the new human B that is considered a reincarnation of human A ?
"According to Buddhism, one's self is made of 5 agregates.", maybe according to whom's ever Buddhism and Buddhists, but the Buddha did not told such. More: he repeatedly stressed out that ones own can not be found in the five aggregates. 

As for what is birth: 


  "And what is birth? Whatever birth, taking birth, descent, coming-to-be, coming-forth, appearance of aggregates, &amp; acquisition of [sense] spheres of the various beings in this or that group of beings, that is called birth. MN 141


And as part of the first Noble truth it's somehow pointless to call it "merely convention" since such would hinder one to take actions for a beyond. So for a serious practitioner it's very needed to avoid people who deny coming into being and the Noble Truths, people of grave wrong view.

What makes you the same person who wrote the question and now reading an answer? Desire? Not-knowing?

And without first things first, your practice becomes nothing but that of the many Jains around: a really poor living of real poor hypocriticals.

May you have an auspicious birth here, since it is the prerequisite of liberation.

(Note: not given for stacks, trade and exchange but as a tiny door out of the wheel of rebirth)