An electro-encephalography system, comprising: (a) an internal device for implantation below a scalp and above a skull of a patient, the internal device comprising: a sensor configured to independently detect signals transmitted from opposite sides of the sensor, the sensor having a top electrode disposed on a top side of an electrically insulating material and a bottom electrode disposed on a bottom side of the same electrically insulating material, thereby forming a double-sided electrode; the bottom electrode for receiving a first signal comprising neurological signals originating from the patient's brain and artifacts originating from sources other than the patient's brain, the first signal comprising a first ratio of the neurological signals to the artifacts; and the top electrode for receiving a second signal comprising the artifacts; and a therapy device for providing therapy to the patient; and (b) an external device in wireless communication with the internal device_, the external device to be worn or carried outside the patient's body, the external device comprising a processing unit for: (i) providing power to the internal device; (ii) receiving data from the bottom and top electrodes, the data comprising the first and second signals; (iii) processing the data received from the bottom and top electrodes to obtain a processed signal, the processed signal comprising a second ratio of the neurological signals to the artifacts, and the second ratio being greater than the first ratio; (iv) determining a neurological state of the patient based on the processed signal; and (v) transmitting instructions to the therapy device for providing therapy to the patient according to the neurological state. (a) an internal device for implantation below a scalp and above a skull of a patient, the internal device comprising: a sensor configured to independently detect signals transmitted from opposite sides of the sensor, the sensor having a top electrode disposed on a top side of an electrically insulating material and a bottom electrode disposed on a bottom side of the same electrically insulating material, thereby forming a double-sided electrode; the bottom electrode for receiving a first signal comprising neurological signals originating from the patient's brain and artifacts originating from sources other than the patient's brain, the first signal comprising a first ratio of the neurological signals to the artifacts; and the top electrode for receiving a second signal comprising the artifacts; and a therapy device for providing therapy to the patient; and a sensor configured to independently detect signals transmitted from opposite sides of the sensor, the sensor having a top electrode disposed on a top side of an electrically insulating material and a bottom electrode disposed on a bottom side of the same electrically insulating material, thereby forming a double-sided electrode; the bottom electrode for receiving a first signal comprising neurological signals originating from the patient's brain and artifacts originating from sources other than the patient's brain, the first signal comprising a first ratio of the neurological signals to the artifacts; and the top electrode for receiving a second signal comprising the artifacts; and a therapy device for providing therapy to the patient; and (b) an external device in wireless communication with the internal device_, the external device to be worn or carried outside the patient's body, the external device comprising a processing unit for: (i) providing power to the internal device; (ii) receiving data from the bottom and top electrodes, the data comprising the first and second signals; (iii) processing the data received from the bottom and top electrodes to obtain a processed signal, the processed signal comprising a second ratio of the neurological signals to the artifacts, and the second ratio being greater than the first ratio; (iv) determining a neurological state of the patient based on the processed signal; and (v) transmitting instructions to the therapy device for providing therapy to the patient according to the neurological state. (i) providing power to the internal device; (ii) receiving data from the bottom and top electrodes, the data comprising the first and second signals; (iii) processing the data received from the bottom and top electrodes to obtain a processed signal, the processed signal comprising a second ratio of the neurological signals to the artifacts, and the second ratio being greater than the first ratio; (iv) determining a neurological state of the patient based on the processed signal; and (v) transmitting instructions to the therapy device for providing therapy to the patient according to the neurological state.