US Patent 9943698 Cognitive enhancement using feedback

In an embodiment, a method includes determining a target frequency corresponding to a target brain state and stimulating a brain of a user using feedback to attempt to achieve the target brain state in the user. The stimulating step may include measuring an electrical output of the brain of the user received from one or more sensors coupled to the user, determining a current frequency associated with the brain of the user based on the measured electrical output, and determining a difference between the current frequency and the target frequency. When the difference between the current frequency and the target frequency is greater than a predetermined amount, the method includes sending a signal to the brain of the user through one or more pathways. The signal may have a frequency operable to modify the current frequency associated with the brain of the user towards the target frequency.