Electrical brain waves (ripples) for memory retrieval, illustration. In a study of epilepsy patients, researchers at the US National Institutes of Health (NIH) found that split seconds before we recall events, tiny high-frequency electrical waves, or ripples, may flow through parts of our brains that help store our memories (e.g. the medial temporal lobe and the neocortex), allowing for successful memory retrieval. Earlier studies have previously indicated that these synchronised ripple oscillations may be important for solidifying memories during sleep.