A treatment being studied to improve brain function in certain brain disorders and in patients treated with chemotherapy for breast cancer. Sensors are placed on a person?s head, which allows brain activity to be shown as patterns on a computer screen. A beep or a tone may be used as a reward to a person for changing certain brain activities. EEG biofeedback may help cancer patients deal with the stress and mental side effects of chemotherapy. Also called neurofeedback.