I was wondering if anyone knew of any evidence of 0 dietary cholesterol intake having any negative effect on cognitive function for a typical human, or whether all necessary cholesterol is produced in vivo.

i don't think there are negative consequences from abstaining from all dietary cholesterol, as the body produces 10x what most people take in on a daily basis anyway. There are negative consequences from abstaining from all dietary fat intake, though.

The need for certain fat-soluble vitamins, perhaps?

that too, but I was thinking of essential fatty acids (EFAs), omega-3 and omega-6, which cannot be constructed within an organism from other components. Deficits in EFA's can cause developmental abnormalities, and lesser effects in adults like dermatitis.