Why is it so difficult to study how the brain creates how this system within our brains evolved and the possible capabilities

The plausible assumption was that there must be a single location where all information about our internal conditions and environment is made available, decisions are taken and actions are initiated. Even Descartes-who considered mental processes to be superior to, rather than connected to, material processes in the brain, and whose free-floating res cogitanswould therefore have needed no circumscribed location-did not believe that it was possible to get by without a singular localizable controlling entity.