Depends on why you seek validation so desperately. Were you neglected? Were you bullied? Are you just really insecure? Yes those would have neurological effects on you that would more than likely lead to seeking approval moreso than others... Do you just want it because you want it? I don't know, probably does have something to do with your brain but I wouldn't know how to explain it.
It's human nature to want approval though. Humans are social creatures. Whether you believe you do or not, it's in your nature to want the approval and acceptance from others. Nobody wants to be discluded, nobody wants to feel unworthy or below others.