Reflex Link

From Tardis Wiki, the free Doctor Who reference

The Reflex Link was a part of a Time Lord's brain which allowed them to tune their brains into "the Time Lord intelligentsia, creating a network which the Fourth Doctor's clone described as "a thousand super-brains in one". According to the clond Fourth Doctor, the Doctor lost the ability to call upon his Link after they "kicked him out". (TV: The Invisible Enemy)