Carbs aren’t essential but protein and fats are. Your body like some carbs which is why it is perfectly happy when you reduce them.
So yes it’s correct that your body, and especially your mind, requires some carbs to function optimally, there are two things to consider:
Firstly that the necessary amount of carbs that your body needs to function well is actually very small.
Secondly that your body can produce the needed glucose via a internal process called gluconeogenesis (GNG). It is precisely for this reason why the human body can even handle a zero-carb style of diet. So it has no problem at all dealing with low carbs in the strict keto range.