1. A method, comprising: implanting at least one electrode in a brain of a subject; receiving electrical signals generated by a plurality of neurons at the at least one implanted electrode, the electrical signals comprising a portion that encodes at least one abstract cognitive concept, the portion of the electrical signals encoding the at least one abstract cognitive concept not encoding either motor movements or intended motor movements, the plurality of neurons having generated the portion of the electrical signals encoding the at least one abstract cognitive concept without having been trained to do so; at least partially decoding the at least one abstract cognitive concept encoded in the portion of the electrical signals by generating a feature set based on the electrical signals and mapping the feature set to the at least one abstract cognitive concept using a transformation rule; and generating a control signal to instruct an external device to perform a task associated with the at least partially decoded at least one abstract cognitive concept.